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HEALTH & DISEASE | VIEW ON WEBSITE

Why disease outbreaks on Chinese fur farms are a serious risk to public health

Farming animals for fur is not only cruel but also provides an ideal environment for viruses to mix and cross over into humans

By Jane Qiu    02.04.2026

Reporting for this story was supported by the Pulitzer Center.

A sharp, musky scent rushes over me as I step out of the taxi outside Mr. Wang’s house near Tong’erpu, in China’s northeastern Liaoning province. It’s one of the country’s largest fur-trading centers. Wang greets me, sporting a blue jersey and matching cap. “I’m about to feed the foxes,” he says.

In his courtyard, 600 Arctic foxes, housed in rows of elevated wire-meshed cages, eye me nervously. Wearing no mask, gloves or protective clothing, Wang moves down the rows, scooping a paste of fish, corn and animal bones into bowls in each cage. The animals, creamy white with short bushy tails, feast on the food amid a frenzied chorus of slurps and gulps.

Like many others in the region, Wang’s fox farm provides an essential supplement for a precarious farming livelihood. But the fur-farming business comes with risks of its own. The price of fur fluctuates greatly from year to year, Wang tells me. And mysterious diseases can strike with devastating force. A few years ago, Wang says, diarrhea wiped out hundreds of his foxes.

China is one of the world’s major fur producers — particularly of fox, mink and racoon dog pelts — alongside Europe and the United States. In 2021, China’s fur-farming industry employed around 6 million people and had an estimated value of US$61 billion.

The kinds of disease outbreaks Wang describes are commonplace, but before Covid-19 they were rarely reported, let alone investigated. Studies since the pandemic have found that some outbreaks, which can kill thousands of animals, were caused by a particularly worrisome virus that can cause severe fever with thrombocytopenia syndrome (SFTS). In humans, this condition can bring about bleeding, vomiting, diarrhea and organ failure. It appears to be afflicting a growing number of people since it was first identified in 2009, says Yu Xuejie, a microbiologist at Wuhan University who discovered the virus that causes the disease. Last year alone, Yu adds, China reported roughly 5,500 confirmed cases — nearly triple the number recorded just five years earlier.

And the SFTS virus isn’t the only one associated with fur farming that has scientists worried. A recent study shows that other viruses capable of infecting people, including coronaviruses and influenza viruses, are widespread in fur animals. With crowded conditions, poor biosafety standards and little surveillance on fur farms, scientists like Eddie Holmes, a virologist at the University of Sydney in Australia and a coauthor of the study, warn that the industry is “spectacularly risky.”

The farms, says Holmes, could be the breeding grounds for the next pandemic.

The questions haunting scientists are urgent: How easily can viruses in fur animals spread? What illnesses could they ignite in people? And how are farming practices helping them along? Soon after my visit to Wang’s farm, outbreaks in both fur animals and humans on multiple farms began to provide clues.

Ticks are considered the primary way that the SFTS virus is transmitted. But studies have shown that the virus can infect many animal species, including people, and may spread without ticks.

Tracking the killer

Severe fever with thrombocytopenia syndrome is not new. Nearly 20 years ago, central China was gripped by waves of a mysterious disease that struck with fever, diarrhea and dangerously low platelet counts — killing nearly a third of the people it touched. “Family members were angry and took to the streets in protest,” demanding that the government uncover the cause of the new disease, recalls Yu, a former employee with the Chinese Center for Disease Control and Prevention in Beijing.

In 2009, Yu led a team into central China to collect blood samples from patients with the unknown illness. Challenging the prevailing belief that a bacterium was to blame, he uncovered a novel RNA virus. His team detected the virus or antibodies against it (a sign of exposure) in 70 percent of hospitalized SFTS patients — evidence compelling enough for the scientists to conclude that this newly identified virus was behind the disease.

Most of the patients lived near forested areas thick with blood-sucking mosquitos and ticks. But when Yu’s team trapped nearly 6,000 mosquitoes, none carried the virus. The real menace, says Yu, surfaced in the ticks. Amongst those pulled off domestic animals, one in 20 tested positive.

Follow-up studies confirmed that Haemaphysalis longicornis, a tick capable of feeding on diverse hosts, is the primary vector of SFTS. Dozens of species, including rodents, birds, goats and cattle, carry antibodies to the virus, indicating past infection. The disease has since surfaced in people in other Asian countries, such as Japan, South Korea, Thailand and Vietnam, killing as many as one in five patients. Most SFTS cases occur in China, and between 1996 and 2023, there were more than three dozen clusters of cases in which infected people transmitted the virus to others.

Then, in fall 2023, word of fox die-offs on farms across eastern China began rippling across veterinarians’ social media feeds. One after another, foxes developed running noses, lost their appetite, passed black stools and then died, within days of first showing symptoms. On each farm, some housing as many as 11,000 foxes, scores of animals perished — in some cases a third of the facility’s creatures.

Equally troubling, says Holmes, is the “zero biosafety” he observed on Chinese fur farms, creating the perfect gateway for these viruses to cross over into people.

Shi Weifeng, a virologist at Shanghai Jiao Tong University of Medicine, sprang into action. Shi, whose research focuses on human diseases caused by pathogens from animals, dispatched his team to collect swabs and organ samples — spleen, intestines, lungs and kidneys — of sick or dead foxes on six farms in Shandong and Liaoning provinces, as well as samples from the farm environments, such as the sinks and animal feed.

Until recently, conventional wisdom was that most animals infected with SFTS showed only mild or no symptoms, says Keun Hwa Lee, a virologist at Hanyang University in Seoul. Yet all but one of the foxes Shi’s team tested were teeming with the virus, their bodies etched by the SFTS infection: organs swollen and mottled with hemorrhage, cells and tissues degenerated.

An analysis of 13 complete viral genomes sequenced from infected foxes found that they sorted into three subtly different but distinct groups. In some cases, the genomes had segments from different viruses — like Lego blocks clicked into new combinations — a reshuffling process known as reassortment. Reassortment, notes Shi, can generate variants that are more infectious, more deadly or both.

The team concluded that multiple lineages of the SFTS virus were circulating across eastern China, crossing into foxes again and again. They are less clear on how the animals got infected, because they found only one tick and it was virus-free.

Yet, around the same time that foxes in Shangdong and Liaoning were dying in droves, thousands of miles away in Finland, bird flu was spreading like wildfire from one fur farm to another. A study led by Lauri Kareinen, lead virologist at the Finnish Food Agency in Helsinki, linked the flu outbreaks to infected black-headed gulls in the region. The gulls, Kareinen explains, regularly flocked to the fur farms to feed — and most likely ignited the spark that set off the viral wildfire.

Kareinen wonders if SFTS outbreaks on farms in China might also have been sparked by infected birds or rodents that were drawn to the farms for scraps and contaminated the foxes’ feed. Another possibility is that some of the raw ingredients used in feed processing could have come from diseased animals. A recent study found that animals can shed the pathogen in their saliva and that healthy animals can fall ill after oral exposure.

Scientists suspect that once the virus gained a foothold in some animals, it could spread from one to another through close contact. A team that managed to isolate the virus from farmed minks observed: “When one caged mink suffers the disease and shows clinical symptoms, the minks nearby will show similar clinical symptoms and soon die.”

Human tolls

Spread of the SFTS virus from one individual to the next does not appear to be limited to nonhumans. In October 2023, not far from the farms where Shi’s team was probing the mysterious fox die-offs, a 60-year-old woman was struck with dizziness, nausea and vomiting. Within two days, she slipped into a coma; she died a week later. Around the same time, a coworker of hers was admitted to the same hospital with a “fever of unknown origin.” Laboratory tests delivered a chilling verdict: The women carried the SFTS virus. Both worked at a farm that housed more than 500 racoon dogs, 6,000 minks and 10,000 foxes.

A team led by Yang Zhenghui, an epidemiologist at the Weihai Heath Commission, descended on the farm like forensic investigators at a crime scene — interviewing workers, swabbing equipment and enclosures, combing for ticks and reconstructing the chain of events.

In October of 2023, two people who worked at a fur farm in Shandong province fell ill; one died a week after the onset of symptoms. An epidemiological investigation of the farm (enclosures and animals shown) found that the two workers, who did not wear protective gear on the job, were probably infected by the SFTS virus while skinning animals.

CREDIT: J. LI ET AL / VIROLOGY JOURNAL 2024

None of the 22 other workers had fallen ill. Yet half of them carried antibodies that pointed to past infection, and one worker tested positive for antibodies that were suggestive of an ongoing infection.

The team found no ticks on the farm or in the fields around the patients’ homes, and neither the women nor their colleagues recalled being bitten by a tick. By contrast, more than three quarters of the workers reported being bitten and splattered with blood while skinning the animals — grim evidence that, despite industry guidelines, some fur animals in China are still skinned without first being killed by electrocution.

Fur farming is poorly regulated in China, says Peter Li, an expert on wildlife policy at the University of Houston-Downtown in Texas. In Europe and the United States, enforcement can also be lax on protective measures, though some places have made improvements since the Covid-19 pandemic. Yang’s team found that the sickened workers had very little knowledge about how to protect themselves from possible diseases while on the job, including when they skinned animals. Samples taken from the skinning area, including blood from two foxes and swabs from the ground and a trash bin, were positive for the SFTS virus. Four of six viral genomes sequenced — one fox sample and three environmental swabs — were 99.9 percent identical to one another and to those from the two patients, pointing to a shared source.

Yang and his colleagues, who did not respond to Knowable’s requests for an interview, hypothesized in their report that the virus carried by the animals might have become aerosolized during the skinning process, exposing workers through inhalation.

Wen Hongling, a public health expert at Shandong University in Jinan who was not involved in the work, says the scenario is plausible: Beneath the animals’ skin lies a dense network of fluids and blood vessels, and the act of skinning can turn them into a fine, invisible mist that lingers in the air and can slip into workers’ lungs. Her studies have shown that mice exposed to such aerosols become infected with the SFTS virus, which then takes hold and replicates in their lungs.

Ticking time bomb

The SFTS story still contains mysteries, says Lee. The repeated die-offs on Chinese fur farms, for instance, struck him as “unusual,” given that the vast majority of infected animal species exhibit few symptoms. Regardless of what made the infections so lethal in fur animals, the story serves as a sobering cautionary tale. Researchers wonder what other deadly viruses might be lurking in these poorly regulated farms.

Holmes and his collaborators in China and elsewhere have uncovered a troubling picture. In one survey, which sampled 461 diseased fur animals across China, the researchers identified nearly 40 viruses with high potential to infect other animals, including people — nearly half of them in Shandong, home to the country’s largest producer of mink and fox furs. A separate study, which sampled 1,941 game animals across the country, found what looks like cross-species jumps of coronaviruses, including four canine coronaviruses in raccoon dogs suffering from diarrhea.

Scientists conducted a large survey in China of fur animals, both farmed and wild, that had died from disease. The analysis of samples from 461 animals found 39 potentially high-risk viruses. These included 11 zoonotic viruses (that is, previously found in people); 13 high-risk novel viruses (meaning the virus comes from a genus that’s been detected in at least three mammalian orders); and 15 viruses that had been previously observed in two or more animal orders. Several of the viruses were detected in more than one species of fur animal, suggesting potential virus transmission between farmed and wild animals, and from humans to farmed animals.

Equally troubling, says Holmes, are the documented instances of “zero biosafety” with farmed animals, creating the perfect gateway for these viruses to cross over into people. In a video captured by his Chinese collaborators, farmers were seen handling raccoon dogs stricken with severe gastric infection — using nothing but their bare hands.

While an increasing number of countries have banned fur farming since the Covid-19 pandemic, out of both animal rights and public health concerns, some scientists remain cautious about advocating for outright bans. In some parts of the world, says Kaneinen, fur farming is deeply rooted in culture and family tradition; in others, it provides a vital source of income. Some argue that a blunt ban ignores these realities and could drive the industry underground — where it would be even harder to monitor and potentially more dangerous.

A more realistic solution, researchers say, is better regulation and a massive improvement in animal welfare in Chinese fur farms. After the bird flu outbreaks in 2023, Finland introduced a series of mandatory measures to make fur farming safer, including installing nets to keep out birds, keeping the fur animals indoors, reducing cage size, and enforcing the use of personal protective equipment. Kareinen and his colleagues also identified the skinning process as “the riskiest phase of the operation,” where biosafety measures should be enforced most rigorously.

Also vital, Holmes adds, is regular surveillance of the pathogens circulating in fur animals and the humans who work with them. Without such measures, if fur animals were to trigger a major epidemic, he says, “we would have completely failed as a society — absolutely and utterly failed.”

Back in Tong’erpu, two foxes clash over feed, their bodies colliding with a metallic rattle against the wire cage that houses them. Wang laments that fur prices have yet to recover since the pandemic, leaving him feeling the pinch. This may be part of a long-term trend that sees the appetite for fur dwindling, both in China and worldwide. Some believe that fur farming, rather than being forced out, will simply fizzle out on its own.

As I walk through the farm, a cold shiver runs down my spine. Every cage could be a ticking time bomb, and the only question is whether one will detonate before the industry itself withers away.

10.1146/knowable-020226-2

Jane Qiu is an award-winning independent science writer in Beijing. @janeqiuchina, @janeqiu.bsky.social

SOCIETY | VIEW ON WEBSITE

Corporate crime persists in the shadows

Unlike violent crimes, there are no comprehensive national statistics on the serious misconduct of companies. Some see a need for change.

By Elise Hansen    02.03.2026

Mary Gay Scanlon cut her teeth in Congress scrutinizing Big Tech’s enormous power over Americans’ lives. As she and fellow representatives on the Judiciary Committee set about their 16-month investigation, she was itching to explore corporate misconduct across a wider swath of industries.

“It seemed like an area that was ripe to address,” Scanlon, a Democratic representative from Pennsylvania, says. “But there was no data.”

Corporate misconduct can have vast consequences, from contaminating groundwater to wiping out retirement savings to fueling an opioid crisis. But there’s a stark contrast between the information on these crimes compared to that on individual crimes such as theft and assault.

“The FBI, who is the predominant supplier of crime data in the United States, does not capture corporate crime data like price fixing, tax evasion, cooking the books — those kinds of things,” says Alexis Piquero, a former head of the Bureau of Justice Statistics, part of the US Department of Justice. Federal records of corporate misconduct do exist, but they tend to be spread across myriad federal agencies, each focused on its own narrow section of the law.

As a result, it’s difficult to determine even the most fundamental questions about corporate crime. How many victims are there? How much does it cost consumers? What kind of companies are most likely to commit crimes, and when? How effective are government interventions and corporations’ own efforts at compliance?

The answers, it seems, are buried in agency basements and muddled by idiosyncratic record-keeping.

“If you were to ask me, ‘Alex, how many price-fixing arrests were made this year?’ The answer would be, ‘I don’t know, and no one else knows either,’” Piquero laments. “And that’s an embarrassment that in 2025 we don’t have the answer to that question.”

A need to share data

That’s not to say the information doesn’t exist. Each federal agency keeps its own records about the corporate crime cases it has opened, the companies involved, the alleged misconduct and the outcome of those cases. But data mostly remain siloed within that agency — not pooled with information from other departments, says Sally Simpson, a criminologist at the University of Maryland, College Park.

“In the United States, there is no centralized data repository that captures the full extent of the phenomenon, by company, across offense types and legal venues (criminal, civil and regulatory),” Simpson writes in the 2025 Annual Review of Criminology, “nor are there systematic data collected from victims or self-reported offenders that can cross-validate official counts.”

On top of that, federal agencies decide for themselves exactly what information they’ll capture and how they will format it. They make different choices, complicating attempts at comprehensive research.

“They all use different criteria for when a case is brought and what kind of information is collected about the case,” says Simpson. “So creating what’s called a crosswalk between all of these different sources of data, so that you’re collecting similar data, becomes quite complex.”

Corporate crime can include numerous kinds of offenses, with wide-ranging consequences. In fiscal year 2024, the US Department of Justice sentenced corporations for 80 crimes that included environmental, fraud, and food-and-drug-related offenses. But the full extent of such misconduct is difficult to track.

Peter Yeager encountered all of this firsthand as a graduate student at the University of Wisconsin–Madison in the 1970s. At the time, he was studying violations of federal law by the 582 largest American corporations. It was not easy. He and his fellow academics had to go to 24 different federal agencies to capture the full spectrum of potential violations.

It was the 1970s, so “we did it with computer cards — 80-column computer cards,” he recalls. “Our output was not on a computer; it was all on paper, and it reached about 10 feet high.”

Yeager ultimately published a comprehensive examination of white collar crime in the US. That was in 1979. Lawmakers have described it as “the last comprehensive DOJ report on corporate crime” — which stirs up mixed feelings in Yeager. “I was pleased to read that,” he says. “But also a little distressed, that that’s the fact still.”

Street crimes yield better data

Today, street crimes and violent crimes such as murders, thefts and assaults, are as pervasive in conversation as ever — discussed constantly at all levels of politics and in the news. Violent crime is frequently rated as important by voters and is a major driver of electoral politics.

“We have a two-tier system of justice. If it’s corporate crime, then you get a slap on the wrist, you pay a fine, and you go on to commit it again, often — versus individuals going to jail for long stretches.”

— MARY GAY SCANLON

And this side of the criminal justice system is carefully studied and documented. The Bureau of Justice Statistics, for example, publishes annual data on violent incidents, broken down by the ages of offenders and victims; on inmate deaths in federal custody; on capital punishment and much more. Crucially, it even conducts a yearly “criminal victimization” survey, in which the government interviews roughly 240,000 citizens about their experiences in the past year with such crimes as robbery, assault and break-ins — regardless of whether respondents reported those incidents to the police.

This effort helps shed light on the “dark figure” or “hidden figure” of crime, meaning offenses that have been committed but haven’t been discovered or reported, so they don’t show up in official statistics. It helps to paint a more complete picture of what’s actually happening on the ground, not just what shows up in court.

But the bureau’s criminal victimization survey does not ask people if, for example, they have been cheated out of wages or lied to by an investment advisor. The “hidden figure” of corporate crime is still very much hidden, says Simpson. The United States doesn’t have systematic data from victims or even from self-reported offenders to help researchers triangulate with the official records.

These disparities rob researchers, policymakers and the public of basic information about the extent of corporate misconduct and how it affects their lives. “We’ve got a whole ream of hypotheses 50 years old,” Yeager says. For example, his 1979 deep dive into major US corporations showed that the large companies of the day were more likely to offend when their sales, profits, earnings and product diversification were trending downward.

The data gaps also make it difficult to determine the effectiveness of the government’s responses. Corporate prosecutions have been trending downward since the early 2000s, and the Department of Justice has come to lean more heavily on non-prosecution agreements and deferred prosecution agreements. In these, companies agree to make changes to their operations and frequently end up paying a fine in order to avoid court. Globally, corporations have been spending billions on internal compliance efforts to prevent legal and regulatory violations. Still, there’s little definitive scholarly research on how well these arrangements work in deterring corporate crime and what the most effective approaches to deterring and policing it may be, says Simpson.

“There are all of these things companies try to do, but we don’t know how successful they are, because we have very few empirical studies,” she says.

Federal prosecutions of corporations have dropped over the years. And the data shown in this chart do not shed light on corporate crimes that were not investigated, or that the US Department of Justice did not bring to court.

Scanlon finds these disparities troubling. “We have a two-tier system of justice,” she says. “If it’s corporate crime, then you get a slap on the wrist, you pay a fine, and you go on to commit it again, often — versus individuals going to jail for long stretches, ending up with mass incarceration.”

Registry of company misdeeds

Some progress has been made to bring corporate misconduct data into public view. The Consumer Financial Protection Bureau launched an initiative in June 2024 to create a public registry of nonbank financial companies that have broken consumer protection laws. At the time, the bureau’s leadership touted the registry as a way to help consumers determine whether a company is trustworthy, and to help the bureau determine which companies are repeatedly violating the law. Bureau representatives did not reply to requests for comment about the program’s status under the Trump administration.

Also, under the Biden administration, the Department of Justice created a website chronicling the latest corporate case resolutions across many offense types, from antitrust to money laundering. But the data start only in 2023, so anyone hoping to look further back would be out of luck. On top of that, the data capture only concluded court cases, thereby missing out on enforcement actions that don’t go through federal courts — such as violations that are pursued only by regulatory agencies.

And while some non-government organizations, such as nonprofits and universities, have made headway in compiling databases for public use, they aren’t part of the official record. Yeager believes the surest way to secure resources for a centralized, government database lies with Congress.

To that end, Scanlon reintroduced the Corporate Crime Database Act in July of 2025. The bill calls for agencies to submit information about their enforcement actions to the Bureau of Justice Statistics, which would then aggregate and analyze the information and publish a database for public use. Previous iterations of the bill have been introduced in eight different years, so far without success.

Industry lobbyists are part of the holdup, in Scanlon’s view. Or, as she puts it, “people who are making money off not being held accountable.” And the Trump administration has backed off from some areas of white-collar policing. But nonpartisan factors are also likely at play: Piquero says he encountered good old-fashioned institutional inertia during his time in the Bureau of Justice Statistics when he attempted to spearhead an initiative to centralize corporate crime data. “There’s this rigidity of ‘this is the way we’ve always done things,’” he says.

From a technical point of view, collecting better data is eminently achievable, Piquero notes. “There’s no reason why it can’t be done. It’s just a matter of people getting together at the table and saying, ‘OK, this is what we’re going to do.’”

10.1146/knowable-020326-1

Elise Hansen is a journalist living in New York City.

SOCIETY | VIEW ON WEBSITE

Recreating the smells of history

Using chemistry, archival records and AI, scientists are reviving the aromas of old libraries, mummies and battlefields

By Kaja Šeruga    01.28.2026

We often learn about the past visually — through oil paintings and sepia photographs, books and buildings, artifacts displayed behind glass. And sometimes we get to touch historical objects or listen to recordings. But rarely do we use our sense of smell — our oldest, most primal way of learning about the environment — to experience the distant past.

Without access to odor, “you lose that intimacy that smell brings to the interaction between us and objects,” says analytical chemist Matija Strlič. As lead scientist of the Heritage Science Laboratory at the University of Ljubljana in Slovenia and previously deputy director of the Institute for Sustainable Heritage at University College London, Strlič has devoted his career to interdisciplinary research in the field of heritage science. Much of his work focused on the preservation and reconstruction of culturally significant scents.

Reconstructed scents can enhance museum and gallery exhibits, says Inger Leemans, a cultural historian at the Royal Netherlands Academy of Arts and Sciences. Smell can provide a more inviting entry point, especially for uninitiated visitors, because there’s far less formalized language for describing smell than for interpreting visual art or displays. Since there’s no “right way” of talking about scent, she says, “your own knowledge is as good as the others’.”

Despite their potential to enrich our understanding of history and art, smells are rarely conserved with the same care as buildings or archaeological artifacts. But a small group of researchers, including Strlič and Leemans, is trying to change that — combining chemistry, ethnography, history and other disciplines to document and preserve olfactory heritage.

Some projects aim to safeguard a beloved smell before it disappears. When the library in London’s St. Paul’s Cathedral was scheduled for renovation, for example, Strlič and his UCL colleague Cecilia Bembibre set about documenting the historic library’s distinct smell.

The team first analyzed the chemicals wafting from the collection, which includes books dating back to the 12th century, and the surrounding furnishings, which have barely changed since the library was completed in 1709. They used a process called gas chromatography-mass spectrometry, which helps separate, identify and quantify volatile organic compounds, to examine air samples they’d captured in the library.

“As an analytical chemist, I was able to characterize and quantify those molecules, but how people describe what they felt required a completely different approach,” says Strlič. To whittle down the list of compounds identified by the mass spectrometer to the ones that humans can actually smell, the researchers next invited seven untrained “sniffers” into the cathedral library and asked them to describe its smell using a list of 21 adjectives commonly used to describe the compounds.

These delicate instruments sample the air wafting through the library of St. Paul’s Cathedral in London, picking up volatile compounds that evoke the collection’s distinctive scent of old books and furniture.

CREDIT: CECILIA BEMBIBRE

The list included words like green and fatty, which people frequently use to describe the smell of the chemical hexanal, and almond, which is associated with benzaldehyde. Both compounds are released by paper as it degrades. The sniffers were also invited to add any descriptors of their own.

One word that all sniffers used to describe the library wasn’t particularly surprising: woody. Others that proved popular were smoky, earthy and vanilla. Such descriptors can help conservators assess the state of old paper, since papers that are slightly more acidic due to decay, for example, “smell more sweet,” says Strlič. “And those that are stable smell more like hay.”

Strlič and colleagues next matched the qualitative descriptors the sniffers had selected with their underlying chemical compounds to create a chemical “recipe” for the scent of the cathedral’s library. Such recipes are published in scientific journals and stored in digital research repositories, so a chemist could theoretically whip up the smell of old books centuries from now, “even if, in the future, people no longer go to a library or no longer read physical books, and only receive all information digitally,” says Strlič.

How musty are mummies?

The work at St. Paul’s Cathedral, which ended in 2016, suggested that it might be possible to capture far older scents — including smells from thousands of years ago. For a study published in 2025, Strlič was joined by scientists from Egypt, Slovenia, Poland and the United Kingdom to study nine ancient Egyptian mummies. The aim was to learn about the mummification process and recreate a scent that will be available to visitors of the Egyptian Museum in Cairo from 2026 onward.

One might expect the scent of millennia-old mummified bodies to be off-putting, to say the least. Yet the smell is surprisingly pleasant, “because the ancient Egyptians used so many aromatic compounds, oils and resins that a lot of the original smell still remains,” Strlič says.

To capture these chemicals, Strlič and colleagues extracted air samples from the sarcophagi, separated them into single compounds with a gas chromatograph and identified them with a mass spectrometer.

By analyzing air next to these mummies at the Egyptian Museum in Cairo, scientists can recreate their scent — and shed light on the embalming ingredients used to preserve them.

CREDIT: CECILIA BEMBIBRE

A panel of eight scientists — all trained on the scent of mummification materials — then evaluated the samples’ smells in terms of quality, intensity and pleasantness. After assessing each sample individually, the group discussed their findings to reach consensus: Woody, spicy and sweet emerged as common descriptors across all nine bodies.

The scent profiles that the team created based on these chemical and sensory observations can now be used to understand which mummies are more degraded than others, and how some of the bodies were mummified in the first place, says Strlič. For example, the team identified embalming ingredients like conifer oils, frankincense, myrrh and cinnamon, as well as more modern compounds, such as synthetic pesticides and plant-based pest oils, which museums have used to preserve the mummies, often without documentation.

CREDIT: JOHN EVERETT MILLAIS / PUBLIC DOMAIN

The Blind Girl

For an exhibition of Pre-Raphaelite painters, which ran at the Barber Institute of Fine Arts and Watts Gallery in the UK from late 2024 to late 2025, historian Christina Bradstreet created two scents for John Everett Millais’ painting The Blind Girl in collaboration with Spanish perfumer Gregorio Sola.

The first scent captured the odor of the rainbow in the background, which Victorians imagined as “the scent of fresh wet grass and flowers, when the sun has just come out after a rainstorm,” says Bradstreet — what we might today describe as “petrichor.”

The second evoked the older girl’s linsey-woolsey head shawl, which the younger girl is smelling as she looks toward the rainbow. While the wool and cotton cloth associated with Victorian workhouse uniforms is a mark of the girls’ poverty, “it’s about comfort as well,” says Bradstreet. “They are homeless, but the blind girl is her younger sister’s home, they’re together. We thought about the musty smell of an old comforter.”

— Kaja Šeruga

Strlič hopes that such research will help to expand the use of smell analysis as a noninvasive research technique, since it doesn’t require removing any physical samples from the studied object. The team also intends to apply its findings to create what amounts to a mummy “perfume” for the Egyptian Museum. For this, they will select up to 15 key chemical compounds from the mix and adjust their ratios to reflect the natural scent, with panels of sniffers comparing the new creation with the original until there’s no perceptible difference between them. “This is a repetitive process that involves a lot of trial and error,” says Strlič.

Creating even the smell of Hell

While old artifacts offer a convenient starting point for olfactory analysis, many historic smells have not been preserved in physical form. To re-create them, researchers must rely on archival documents and a certain amount of creative interpretation. That’s what a European olfactory heritage project called Odeuropa did for a number of historical events, sites and even ideas, including the Battle of Waterloo and 17th century Amsterdam canals. The team even re-created the scent of Christian “Hell” as described in 16th century sermons, including notes of sulfur and brimstone and a whiff of “a million dead dogs.”

“Olfaction helps shape our cultures, although it often does so unknowingly or without us noticing,” says Leemans, who led the Odeuropa project. “When we talk about cultural heritage, we can think about religious rituals, but we can also think about specific scents that we’ve been cherishing and living with for a long time.”

To reconstruct these complex historic “smellscapes,” Leemans and her colleagues scoured old document archives and images for any related smell references. “We search for nose witnesses, people describing those smells,” she says. “But we also look at the components of that smellscape,” such as architectural descriptions listing building materials.

To accelerate the work, Odeuropa has created an AI-driven database of more than 2.5 million historical smell references, mined from 43,000 images and 167,000 historical texts published in seven European languages.

When it’s time to create a real perfume based on this data, Odeuropa researchers write a detailed brief outlining the smell’s relevant components as well as the story behind it. Working with a perfume and fragrance company, they begin evaluating iterations of the scent in different ways — by asking panels of sniffers to assess the scent blind or after a short presentation on the subject, or by approaching curatorial, academic and fragrance experts to peer-review the fragrance.

To each their own odors

A person’s perception of smell is inherently subjective and dependent on their unique biology, personal experience and culture, says neuroscientist Gülce Nazlı Dikeçligil at the University of Pennsylvania, and lead author of a 2024 Annual Review of Psychology on human olfaction. “The olfactory system isn’t necessarily optimized for certainty and consistency,” she says. Instead of simply identifying molecules from the environment with computer-like precision, our brains are asking, “What does this molecule mean to me now, in the context of my history?”

As our oldest sense, evolutionarily speaking, olfaction enjoys priority access to brain regions like the amygdala and hippocampus, which are key in processing emotion and memory, notes Dikeçligil. This means that the memories triggered by scents tend to be especially vivid and emotionally significant.

Scent “sparks thoughts, memories, ideas and gets people talking about and in front of paintings, which is what I want,” says art historian Christina Bradstreet from the Association for Art History in the UK. She recently worked with the renowned Spanish perfumer Gregorio Sola to create three scents to accompany two paintings in a British exhibition on Pre-Raphaelite art. When, in 2022, the Prado Museum in Madrid created 10 scents to accompany Jan Bruegel the Elder’s painting The Sense of Smell — including jasmine, fig tree and civet — they found that visitors lingered in front of the painting for 13 minutes, compared to the average 32 seconds.

Museums and galleries worldwide are taking note and increasingly integrating scent into their exhibitions. This attracts new visitors and engages them in a different way, “not only with the collection, but also with each other,” says Leemans. “When people start to smell, they immediately start to talk to each other, exchanging their memories, their emotions, their knowledge about the scents. It’s a really open conversation that you evoke in the museum space.”

10.1146/knowable-012826-2

Kaja Šeruga is a freelance journalist based in Vienna, where she enjoys the smell of old coffeehouses and even older libraries. You can learn more about her work on her website.

PHYSICAL WORLD | VIEW ON WEBSITE

Meet the mysterious electrides

These chemical oddities may explain why Earth seems to be deficient in certain elements — and could prove useful in catalysts and more

By Rachel Brazil    01.26.2026

For close to a century, geoscientists have pondered a mystery: Where did Earth’s lighter elements go? Compared to amounts in the Sun and in some meteorites, Earth has less hydrogen, carbon, nitrogen and sulfur, as well as noble gases like helium — in some cases, more than 99 percent less.

Some of the disparity is explained by losses to the solar system as our planet formed. But researchers have long suspected that something else was going on too.

Recently, a team of scientists reported a possible explanation — that the elements are hiding deep in the solid inner core of Earth. At its super-high pressure — 360 gigapascals, 3.6 million times atmospheric pressure — the iron there behaves strangely, becoming an electride: a little-known form of the metal that can suck up lighter elements.

Study coauthor Duck Young Kim, a solid-state physicist at the Center for High Pressure Science & Technology Advanced Research in Shanghai, says the absorption of these light elements may have happened gradually over a couple of billion years — and may still be going on today. It would explain why the movement of seismic waves traveling through Earth suggests an inner core density that is 5 percent to 8 percent lower than expected were it metal alone.

Electrides, in more ways than one, are having their moment. Not only might they help solve a planetary mystery, they can now be made at room temperature and pressure from an array of elements. And since all electrides contain a source of reactive electrons that are easily donated to other molecules, they make ideal catalysts and other sorts of agents that help to propel challenging reactions.

One electride is already in use to catalyze the production of ammonia, a key component of fertilizer; its Japanese developers claim the process uses 20 percent less energy than traditional ammonia manufacture. Chemists, meanwhile, are discovering new electrides that could lead to cheaper and greener methods of producing pharmaceuticals.

Today’s challenge is to find more of these intriguing materials and to understand the chemical rules that govern when they form.

The ammonia production plant at Ludwigshafen, Germany, has operated for more than a century. It was the first to use the Haber-Bosch process, which garnered Nobel Prizes for its inventor and developer, Fritz Haber and Carl Bosch. Today, plants including this one run by the chemical company BASF are seeking more renewable ways to produce ammonia.

CREDIT: BASF SE

Electrides at high pressure

Most solids are made from ordered lattices of atoms, but electrides are different. Their lattices have little pockets where electrons sit on their own.

Normal metals have electrons that are not stuck to one atom. These are the outer, or valence, electrons that are free to move between atoms, forming what is often referred to as a delocalized “sea of electrons.” It explains why metals conduct electricity.

The outer electrons of electrides no longer orbit a particular atom either, but they can’t freely move. Instead, they become trapped at sites between atoms that are called non-nuclear attractors. This gives the materials unique properties. In the case of the iron in Earth’s core, the negative electron charges stabilize lighter elements at non-nuclear attractors that were formed at those super-high pressures, 3,000 times that at the bottom of the deepest ocean. The elements would diffuse into the metal, explaining where they disappeared to.

In an experiment, scientists simulated the movement of hydrogen atoms (pink) into the lattice structure of iron at a temperature of 3,000 degrees Kelvin (2,727 Celsius), at pressures of 100 gigapascals (GPa) and 300 GPa. At the higher pressure (right) an electride forms, as indicated by the altered distribution of the hydrogen observed within the iron lattice — these would represent the negatively charged non-nuclear attractor sites to which hydrogen atoms bond, forming hydride ions. Duck Young Kim and his coauthors think that the altered hydrogen distribution at higher pressure in these simulations is good evidence that an electride with non-nuclear reactor sites forms within the iron of Earth’s core.

The first metal found to form an electride at high pressure was sodium, reported in 2009. At a pressure of 200 gigapascals (2 million times greater than atmospheric pressure) it transforms from a shiny, reflective, conducting metal into a transparent glassy, insulating material. This finding was “very weird,” says Stefano Racioppi, a computational and theoretical chemist at the University of Cambridge in the United Kingdom, who worked on sodium electrides while in the lab of Eva Zurek at the University at Buffalo in New York state. Early theories, he says, had predicted that at high pressure, sodium’s outer electrons would move even more freely between atoms.

The first sign that things were different came from predictions in the late 1990s, when scientists were using computational simulations to model solids, based on the rules of quantum theory. These rules define the energy levels that electrons can have, and hence the probable range of positions in which they are found in atoms (their atomic orbitals).

Simulating solid sodium showed that at high pressures, as the sodium atoms get squeezed closer together, so do the electrons orbiting each atom. That causes them to experience increasing repulsive forces with one another. This changes the relative energies of every electron orbiting the nucleus of each atom, Racioppi explains — leading to a reorganization of electron positions.

The result? Rather than occupying orbitals that allow them to be delocalized and move between atoms, the orbitals take on a new shape that forces electrons into the non-nuclear attractor sites. Since the electrons are stuck at these sites, the solid loses its metallic properties.

Adding to this theoretical work, Racioppi and Zurek collaborated with researchers at the University of Edinburgh to find experimental evidence for a sodium electride at extreme pressures. Squeezing crystals of sodium between two diamonds, they used X-ray diffraction to map electron density in the metal structure. This, they reported in September 2025, confirmed that electrons really were located in the predicted non-nuclear attractor sites between sodium atoms.

This graphic shows alternative models for metal structures. At left is the structure at ambient conditions, with each blue circle representing a single atom in the metallic lattice consisting of a positively charged nucleus surrounded by its electrons. The electrons can move freely throughout the lattice in what is known as a “sea of electrons.” Earlier theories of metals at high pressures assumed a similar structure, with even greater metallic characteristics (top, right), but more recent modeling shows that in some metals like sodium, at high pressure the structure changes (bottom, right) to a system in which the electrons are localized (dark blue boxes) between the ionic cores (small light blue circles) — an electride. This gives the structure very different properties.

Just the thing for catalysts

Electrides are ideal candidates for catalysts — substances that can speed up and lower the energy needed for chemical reactions. That’s because the isolated electrons at the non-nuclear attractor sites can be donated to make and break bonds. But to be useful, they would need to function at ambient conditions.

Several such stable electrides have been discovered over the last 10 years, made from inorganic compounds or organic molecules containing metal atoms. One of the most significant, mayenite, was found by surprise in 2003 when material scientist Hideo Hosono at the Institute of Science Tokyo was investigating a type of cement.

Mayenite is a calcium aluminate oxide that forms crystals with very small pores — a few nanometers across — called cages, that contain oxygen ions. If a metal vapor of calcium or titanium is passed over it at high temperature, it removes the oxygen, leaving behind just electrons trapped at these sites — an electride.

Unlike the high-pressure metal electrides that switch from conductors to insulators, mayenite starts as an insulator. But now its trapped electrons can jump between cage sites (via a process called quantum tunnelling) — making it a conductor, albeit 100 to 1,000 times less conductive than a metal like aluminum or silver. It also becomes an excellent catalyst, able to surrender electrons to help make and break bonds in reactions.

By 2011, Hosono had begun to develop mayenite as a greener and more efficient catalyst for synthesizing ammonia. Over 170 million metric tons of ammonia, mostly for fertilizers, is produced annually via the Haber-Bosch process, in which metal oxides facilitate hydrogen and nitrogen gases reacting together at high pressure and temperature. It is an energy-intensive, expensive process — Haber-Bosch plants account for some 2 percent of the world’s energy use.

In Haber-Bosch, the catalysts bind the two gases to their surfaces and donate electrons to help break the strong triple bond that holds the two nitrogen atoms together in nitrogen gas, as well as the bonds in hydrogen gas. Because mayenite has a strong electron-donating nature, Hosono thought mayenite would be able to do it better.

In Hosono’s reaction, mayenite itself does not bind the gases but acts as a support bed for nanoparticles of a metal called ruthenium. First, the nanoparticles absorb the nitrogen and hydrogen gases. Then the mayenite donates electrons to the ruthenium. These electrons flow into the nitrogen and hydrogen molecules, making it easier to break their bonds. Ammonia thus forms at a lower temperature — 300 to 400° C — and lower pressure — 50 to 80 atmospheres— than with Haber-Bosch, which takes place at 400 to 500° C and 100 to 400 atmospheres.

This graphic shows the proposed reaction mechanism when ammonia (NH₃) is synthesized using a catalyst consisting of the metal ruthenium along with mayenite, a stable electride. The strong electron-donating properties of mayenite (left) make it easier for nitrogen molecules to break apart and the atoms to be absorbed onto the ruthenium surface. Hydrogen, meanwhile, can be stored in the cages in the mayenite (bottom left) where negatively charged electrons are located. The hydrogen can move from cage to cage and be released onto the ruthenium surface to react with the nitrogen. These processes make ammonia formation more efficient.

In 2017, the company Tsubame BHB was formed to commercialize Hosono’s catalyst, with the first pilot plant opening in 2019, producing 20 metric tons of ammonia per year. The company has since opened a larger facility in Japan and is setting up a 20,000-ton-per year green ammonia plant in Brazil to replace some of the nation’s fossil-fuel-based fertilizer production. The company estimates that this will avoid 11,000 tons of CO_2 emissions annually — about equal to the annual emissions of 2,400 cars.

There are other applications for a mayenite catalyst, says Hosono, including a lower-energy conversion of CO_2 into useful chemicals like methane, methanol or longer-chain hydrocarbons. Other scientists have suggested that mayenite’s cage structure also makes it suitable for immobilizing radioactive isotope waste in nuclear power stations: The electrons could capture negative ions like iodine and bromide and trap them in the cages.

Mayenite has even been studied as a low-temperature propulsion system for satellites in space. When it is heated to 600° C in a vacuum, its trapped electrons blast from the cages, causing propulsion.

Organic electrides

The list of materials known to form electrides keeps growing. In 2024, a team led by chemist Fabrizio Ortu at the University of Leicester in the UK accidentally discovered another room-temperature-stable electride made from calcium ions surrounded by large organic molecules, together known as a coordination complex.

He was using a method known as mechanical chemistry — “You put something in a milling jar, you shake it really hard, and that provides the energy for the reaction,” he says. But to his surprise, electrons from the potassium he had added to his calcium complex were not donated to the calcium ion. Instead, what formed “had these electrons that were floating in the system,” he says, trapped in sites between the two metals.

Unlike mayenite, this electride is not a conductor — its trapped electrons do not jump. But they allow it to facilitate reactions that are otherwise hard to get started, by activating unreactive bonds, doing a job much like a catalyst. These are reactions that currently rely on expensive palladium catalysts.

The scientists successfully used the electride on a reaction that joins two pyridine rings — carbon rings containing a nitrogen atom. They are now examining whether the electride could assist in other common organic reactions, such as substituting a hydrogen atom on a benzene ring. These substitutions are difficult because the bond between the benzene ring carbon and its attached hydrogen is very stable.

There are still problems to sort out: Ortu’s calcium electride is too air- and water-sensitive for use in industry. He is now looking for a more stable alternative, which could prove particularly useful in the pharmaceutical industry to synthesize drug molecules, where the sorts of reactions Ortu has demonstrated are common.

Still questions at the core

There remain many unresolved mysteries about electrides, including whether Earth’s inner core definitely contains one. Kim and his collaborators used simulations of the iron lattice to find evidence for non-nuclear attractor sites, but their interpretation of the results remains “a little bit controversial,” Racioppi says.

Sodium and other metals in Group 1 and Group 2 of the periodic table of elements — such as lithium, calcium and magnesium — have loosely bound outer electrons. This helps make it easy for electrons to shift to non-nuclear attractor sites, forming electrides. But iron exerts more pulling power on its outer electrons, which sit in differently shaped orbitals. This makes the increase in electron repulsion under pressure less significant and thus the shift to electride formation difficult, Racioppi says.

Electrides are still little known and little studied, says computational materials scientist Lee Burton of Tel Aviv University. There is still no theory or model to predict when a material will become one. “Because electrides are not typical chemically, you can’t bring your chemical intuition to it,” he says.

Burton has been searching for rules that might help with predictions and has had some success finding electrides from a screen of 40,000 known materials. He is now using artificial intelligence to find more. “It’s a complex interplay between different properties that sometimes can all depend on each other,” he says. “This is where machine learning can really help.”

The key is having reliable data to train any model. Burton’s team only has actual data from the handful of electride structures experimentally confirmed so far, but they also are using the kind of modeling based on quantum theory that was carried out by Racioppi to create high-resolution simulations of electron density within materials. They are doing this for as many materials as they can; those that are confirmed by real-world experiments will be used to train an AI model to identify more materials that are likely to be electrides — ones with the discrete pockets of high electron density characteristic of trapped electron sites. “The potential,” says Burton, “is enormous.”

10.1146/knowable-012626-2

Rachel Brazil is a science writer based in London.

LIVING WORLD | VIEW ON WEBSITE

Microbial Olympics: Super-duper one-celled athletes

They race, they leap, they spin, they shoot. Meet the organisms for whom physical prowess is more than sport — it’s a matter of life and death.

By Amber Dance    01.22.2026

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In winter sports, lugers slide at more than 90 miles per hour, hockey players send the puck zipping across the ice at 100 mph, and figure skaters spin up to 342 rotations per minute. That’s fast.

But these human feats don’t seem so impressive when compared with the speed demons of the microbial world. In these ongoing games, minuscule predators and their prey hit high velocities during the chase. Hungry microbes make amazing leaps for food. Others hurl bits of their bodies or expand or contract with more force than astronauts experience at takeoff. Skier Lindsey Vonn has nothing on these speedsters.

Microbes accomplish these athletic feats even though they’re so small that their surroundings push back on them: A microbe paddling through water is like a skier trying to cut through a course neck-deep in honey. And they face life-or-death competitions in an unending evolutionary race. “The small world is not a very kind world,” says Manu Prakash, a bioengineer and oceanographer at Stanford University and coauthor of an article on ultrafast microbes in the 2025 Annual Review of Microbiology. “Either you are running away from something, or you are chasing something.”

Here, Knowable Magazine profiles speedy microbes that deserve their own medals.

Fastest bacteria

For pure speed, the reigning champ is an egg-shaped bacterium called Candidatus  Ovobacter propellens (the name remains unofficial because scientists haven’t yet fully described it or grown it alone in a test tube). Discovered half a meter deep in the sands off Denmark’s coast, it uses its 400 tail-like flagella to swim at up to one millimeter per second.

But pitting all microbes against each other in a single race would be unfair. Some are big and some are small, which means they face different resistance from their surroundings. So in their review, the authors calculated speed in terms of body lengths per second.

For Candidatus O. propellens, a large-ish bacterium at four to five micrometers across, its top speed translates to about 200 body lengths per second. It is knocked off the winner’s podium by Magnetococcus marinus, a ball-shaped critter just a micrometer or two across that swims at up to 500 body lengths per second. Compare that to luge, deemed the fastest winter Olympic sport, where athletes zoom at about 25 body lengths per second.

The microbe Candidatus Ovobacter propellens, seen here in cross-section (top) and side view (bottom), has a tuft of about 400 flagella that it uses to swim quickly. (It also possesses unusual membrane features of unknown purpose, including stacked membranes (sm) and a membrane band (mb).)

CREDIT: T. FENCHEL & R. THAR / FEMS MICROBIOLOGY ECOLOGY 2004

The particular M. marinus specimen that scientists clocked for speed was isolated from estuary waters in Rhode Island. When researchers first set up a new 3D microscope to observe this speedster, it tumbled so rapidly that they still had trouble assessing its path, recalls Damien Faivre, an interdisciplinary scientist at the University of Latvia in Riga.

After switching to a different microscope, Faivre and colleagues saw that M. marinus swam in a helical trajectory like a figure skater performing a multi-rotation axel. It moves using two rotating bundles of seven flagella each, one in front and one in back. Tracing that corkscrew motion was key to awarding M. marinus its record, says Faivre: When the scientists calculated the microbe’s speed based on that total distance, “it was actually traveling way more than expected.”

The microbe is called Magnetococcus because it possesses a string of magnetite crystals that acts like a little compass, helping it to navigate to the low-oxygen places it prefers. Someday, it might deliver medicines to the low-oxygen interiors of tumors. In one study, scientists stuck dozens of membranous satchels full of medicine all over the bacteria, injected them into mice, and used magnets to guide them close to tumors. From there, the microbes’ preferences for low oxygen drew more than half of them to penetrate the tumors.

Fastest archaea

Archaea are another domain of microbes, as distinct from bacteria as humans are, and were once thought to be slower swimmers.

Scientists disproved that notion in a 2012 analysis. Their top speedster, by body length, was Methanocaldococcus villosus, and it could give M. marinus a run for its money. A roundish microbe one to two micrometers across that loves hot places and spews methane, it clocked in at up to 468 body lengths per second.

M. villosus was discovered in a hydrothermal vent north of Iceland. It uses its more than 50 flagella not just to swim, but also to attach to surfaces like the walls of “black smokers,” chimneys around hydrothermal vents. Sometimes it uses those flagella to link with other M. villosus microbes.

This kind of speed generates heat. Take speed skater Erin Jackson, who won gold in Beijing in 2022 with a time of 37.04 seconds in the 500-meter. Propelling her five-foot-five-inch body some 500 body lengths per second would have gotten her to the finish line in about 0.6 seconds. But a human athlete, if they could accomplish that, would explode, says Prakash. Microorganisms can be fast because they are small. They have more surface area for their volume than larger critters, so they can release enough heat through exterior membranes.

Speedy squeezers

Figure skaters like Ilia Malinin tuck in their arms to spin faster, but the protozoan Spirostomum ambiguum performs a more extreme tuck. It can squish down to less than half the length of its wormlike one- to four-millimeter body in just five milliseconds.

But S. ambiguum isn’t leaping or spinning through the brackish waters it calls home. When it contracts, it squeezes out toxins to defend itself from predators. Prakash’s group reported that this superfast scrunch also generates a liquid vortex that tells neighboring cells something’s up. The wave, amplified as each microorganism squeezes in response, travels hundreds of times faster than the microbes can swim. Like ice hockey players working together, the microbial team synchronizes toxin-spewing.

As S. ambiguum scrunches, it feels acceleration of up to 15 g’s, on the low end of what a jet fighter pilot would experience upon ejecting from an aircraft. This force should destroy the cell’s innards; if Malinin shrank to even half his size, it’s safe to say he’d never perform another axel. Prakash’s team found that S. ambiguum is protected by a meshwork of its own interior membranes that serves as a shock absorber.

Spirostomum ambiguum, which can grow as long as 4 millimeters, can scrunch itself down to less than half its length — in a mere 5 milliseconds.

CREDIT: TIERBILD OKAPIA / SCIENCE SOURCE

Extreme expanders

If S. ambiguum does a big crunch, Pyrocystis noctiluca does the opposite: This glow-in-the-dark ocean plankton balloons to six times its starting size in under 10 minutes.

P. noctiluca lives an up-and-down life, transiting a vertical range of over 50 meters in the water column on a weekly round trip. Prakash, who described the rapid inflation in microbes collected off Hawaii, calls it the “world’s best marathon runner.”

At the top of its range, some 60 meters from the surface, P. noctiluca is about 200 to 700 micrometers across. There it uses photosynthesis to collect energy from sunlight. But it also needs nutrients more easily found deeper down. So it sinks, thanks to gravity, to a depth of about 150 meters, where it completes its cell cycle, dividing in two. But if those newborn cells drop too deep, they can’t overcome gravity and water pressure to rise. So they make what Prakash and colleagues describe as a “slingshot” maneuver. The microbes suck in fresh water, diminishing their density so that they rise like buoys.

Super shooters

Our final speedster is a parasite that impales host cells with a harpoon that it can shoot at upwards of 300 micrometers per second. Anncaliia algerae is a type of microsporidium, a group containing more than 1,700 species that collectively infect most kinds of animals and contaminate waterways and foodstuffs. More than a dozen of these species, including A. algerae, can infect humans, though it’s unclear how often this happens. The infection can be asymptomatic or mild, causing a variety of symptoms such as diarrhea. It can be fatal in people with weakened immune systems.

A. algerae floats along as a dormant, egg-shaped spore about four micrometers long, with its 100-micrometer-long harpoon, called the “polar tube,” coiled snugly within. Should that spore land in a suitable environment, such as someone’s small intestine, it shoots its shot. The harpoon’s speed might help it penetrate mucus coating the intestinal cells, speculates Gira Bhabha, a structural cell biologist at Johns Hopkins University in Baltimore.

Spores of the parasite Anncaliia algerae (micrograph, left) possess a harpoon-like tube tightly coiled within (diagram, right). When the time is right, the spore unfurls the tube to penetrate a host.

CREDIT: R. CHANG ET AL / ELIFE 2024

Before the tube has even fully extended, the infectious material — at least two sets of fungal DNA, and perhaps the whole cell, Bhabha says — begins its journey through the tube. Though the tube is just 100 nanometers across, and the nuclei containing the DNA are seven times that, somehow they squeeze through, moving almost as fast as the tube unfurled itself.

Microsporidia were discovered more than 150 years ago, but scientists are still trying to work out how they manage these physical feats. Bhabha and Prakash suspect that the harpoon may evert as it emerges, like a sock being flipped inside-out.

Studying microbial Olympians is about more than busting records — it’s about defining the extremes that living things are capable of, says Prakash. These organisms exist in a completely different world from us, experiencing physical constraints and opportunities we don’t intuitively understand.

Plus, Prakash adds, figuring out that world could inspire novel inventions; he thinks S. ambiguum’s braking system could work at human scales, too.

“In the extreme,” he says, “always lies a gem.”

10.1146/knowable-012226-1

Amber Dance is a freelance science journalist and a special contributor for Knowable Magazine. She spent her PhD with Bacillus subtilis, a relative slowpoke with a swimming speed of about five body lengths per second.

TECHNOLOGY | VIEW ON WEBSITE

Field of clones: How horse replicas came to dominate polo

In Argentina, equine cloning in polo is no longer a rarity. It’s now a mature industry — although ethical dilemmas surrounding it persist.

By Maximiliano Fernández    01.21.2026

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At the slightest touch of the reins, he felt a familiarity that shook him. It was 2016, and polo player Adolfo Cambiaso — considered the best in the world — was riding for the first time on a genetic clone of Cuartetera, his flagship mare. The same explosive start, the same agility in the curves, the same sustained stride in the long sprints. “It was the same,” he recalls. “Same movements, same head.... I couldn’t believe it.” It took only a few seconds for him to realize that his gamble — which many had dismissed as nonsense — had paid off.

Cambiaso, now 50, had seen before anyone else, back in 2006, the opportunity to preserve the genetics of his most exceptional horses through cloning and thus perpetuate his La Dolfina team, from the province of Buenos Aires, at the top of polo for generations.

That year, in the middle of the Palermo Open final — the ultimate temple of polo — his horse Aiken Cura suffered a devastating fracture and had to be put down. But before saying goodbye, Cambiaso made an unusual request to the veterinarians. “Just in case, before they put him to sleep, I said, ‘Let’s save some cells.’” It was nothing more than a hunch. He had heard the story of Dolly the sheep, the first mammal cloned from an adult cell, and the idea stuck in his mind.

That intuition two decades ago led to a radical change in the world of polo. La Dolfina, now with more than 150 cloned horses, has established unprecedented dominance, and Argentina has become the world center for horse cloning, far ahead of the United States and Europe. Over the years, laboratories have refined the procedure and improved the success rate — although it remains low.

Hence the high costs: Cloning a horse involves far more investment than that required to breed a good specimen the traditional way. And although equine cloning is no longer a rarity but a mature industry, the ethical dilemmas surrounding it — animal welfare, fair competition and the extent to which biology should be manipulated for sporting purposes — still persist.

Making genetic copies of mammals

In all mammals, including horses, the cloning process is similar. First, a somatic cell —a nonreproductive cell such as a skin cell — is taken from the animal to be cloned, and its nucleus, which contains the genetic information, is extracted. At the same time, scientists take an egg cell from the same species and remove its nuclear DNA, in a process called enucleation. The nucleus that was extracted from the first cell is then inserted into this “empty” egg cell.

Next, that egg with its new nucleus is stimulated chemically or by electrical impulses to begin dividing and form an embryo. The embryo is cultured in vitro for seven or eight days until it reaches the blastocyst stage, at which point it is implanted in a female who will carry the pregnancy to term.

The method is called somatic cell nuclear transfer. It was used to create Dolly the sheep in 1996, a milestone that proved it was possible to “reset” an animal’s DNA and bring it to an embryonic state capable of development, although with major challenges along the way.

Horse clones — like those of other mammals — are obtained through the technique of somatic cell nuclear transfer (SCNT). The nucleus of a non-reproductive cell from the animal to be cloned is inserted into an egg cell that has had its own nuclear DNA removed. After activation, the embryo begins to divide. When it reaches the blastocyst stage, it is implanted into a recipient mare, which will carry the pregnancy to term.

Since Dolly, more than 25 species of mammals have been successfully cloned, including cattle, sheep, goats, pigs, horses, dogs, cats and wild species such as gray wolves and ferrets. The main limitations of cloning lie in the fact that the transferred nucleus does not always manage to reprogram itself completely, and that the mitochondria of the recipient egg and the genome of the transferred nucleus may have incompatibilities, explains Andrés Gambini, a veterinarian specializing in animal reproduction at the University of Queensland in Australia.

Mitochondria are small structures within cells that produce the energy necessary for them to function. They contain DNA of their own, and for this reason clones are not entirely genetically identical to each other. Although they share the same nuclear DNA from the original animal, the mitochondrial DNA will differ because it comes not from the original animal but from the female oocyte that was used in the cloning process. Though its DNA represents a tiny fraction of the total genome, it plays a critical role in the cell, and so those small variations can translate into differences of function and appearance, says Sebastián Demyda Peyrás, an equine geneticist at the University of Cordoba, Spain.

In addition, he says, “epigenetic patterns in cloning are altered much more frequently than in natural pregnancies. Both factors — mitochondrial replacement and epigenetics — influence the higher rate of miscarriages and the number of clones born with health problems, placental abnormalities or severe physical problems.” (Epigenetics refers to the way that genes may be turned on or off due to the addition or removal of small chemical groups, without affecting the DNA sequence itself.)

Despite its technical challenges, cloning has opened the door to many applications, such as species conservation, livestock breeding and even attempts to bring back extinct species. In the field of conservation, genetic material stored in biobanks can be used to reestablish a healthy breeding population, improving genetic diversity and increasing the number of animals that can reproduce, says Aleona Swegen, a reproductive veterinarian at the University of Newcastle, Australia, and coauthor of a 2024 overview of cloning in conservation in the Annual Review of Animal Biosciences. The main challenges, she says, are the need to find an adequate number of oocytes from closely related species and suitable surrogate mothers for gestation.

Cloning also continues to face challenges in domestic animals. A critical moment, different for each species, is when the embryo stops relying on RNA and proteins from the maternal egg and begins to use its own DNA, says Pablo Ross, chief scientific officer at STgenetics, a global leader in bovine reproductive biotechnology, and an animal geneticist at the University of California, Davis. In cattle, this step, known as embryonic genome activation, occurs when the embryo has between eight and 16 cells, while in horses it occurs when it has four to eight cells.

In horses, as in other species, public protocols for cloning already exist, but success depends on the expertise of the team and technical details that are not always included in manuals. A critical issue in horses is the source of the oocytes. One alternative is to obtain them from the ovaries of dead mares collected at slaughterhouses, although they can also be extracted from live females by transvaginal aspiration, a more invasive procedure but with better success rates.

With oocytes obtained using transvaginal aspiration, the proportion of embryos that reach the blastocyst stage is around 35 percent, compared to just 26 percent in oocytes obtained from slaughterhouses. And the difference widens in later stages: Among mares that remain pregnant after day 42, just over half of pregnancies derived from eggs obtained by transvaginal aspiration result in healthy foals, compared to just one in 10 when the eggs come from slaughterhouses.

This graph compares the success of equine cloning according to the origin of the oocytes. Those obtained from live mares by transvaginal aspiration show better results than those collected in slaughterhouses post mortem.

In recent years, several advances have improved horse cloning, says Flávio Vieira Meirelles, a reproductive biotechnologist at the University of São Paulo, Brazil. These mainly involve methods for activation of the egg after inserting the nucleus, and cultivation conditions for the embryo. In addition, the efficiency with which the genes of the donated nucleus are reprogrammed — a process that is carried out by chemicals in the cytoplasm of the egg — has improved.

Greater success, too, is achieved when the donated nuclei come from adult stem cells — which are capable of renewing themselves and transforming into various tissues within an organ — compared with nuclei from fully differentiated cells from a tissue such as skin. The differentiated cells carry more “memory” of their original function. Also, cells from young animals tend to respond better than those from older animals. And, of course, the reproductive capacity of the female surrogate mothers plays a role, too. Even with everything optimized, the birth rate per transferred embryo is low in large mammals, ranging from 3 to 10 percent.

Despite the difficulties, cloning has expanded and today fuels an industry as diverse as it is disturbing: Exceptional cattle are cloned to produce high-quality meat, companion animals are cloned for owners who are unable to say goodbye to their pets (and are willing to invest $50,000 in a clone of their dog or cat), and extraordinary polo horses are cloned to try to ensure victory on the field.

Argentina: Epicenter of horse cloning

In 2010, while completing his doctoral thesis on cloning at the University of Buenos Aires, biotechnologist Gabriel Vichera came across a news story that shook him: Adolfo Cambiaso had auctioned off one of the clones of his star mare, Cuartetera, for an eye-watering $800,000. It was the first time that a cloned animal bred for high athletic performance had been presented as a high-value asset, and in a market where polo horses can be worth anywhere from $50,000 to nearly $1 million for extraordinary specimens, the sale made it clear that there was money waiting to be made.

That clone of Cuartetera had been created in the United States. Vichera wondered if he could bring the technique to Argentina and scale it up. At that time, the University of Buenos Aires had the technology to perform cloning, and a favorable ecosystem to carry out the work was beginning to form in the country. Polo, with horses valued as works of art and team owners obsessed with preserving winning genetics, seemed like the perfect terrain to explore. “Planning to clone these exceptional horses represented a huge business opportunity,” says Vichera.

Even as the news of Cuartetera sparked both amazement and controversy due to ethical concerns about manipulating animals for sporting purposes, Vichera, along with two partners, founded a company to optimize and standardize the cloning process and make it a common tool in professional polo.

On November 18, 2023, in Buenos Aires, before the beginning of a Triple Crown match — the three most prestigious polo tournaments in the world — several polo teams presented their cloned horses. It was a ceremony honoring Cuartetera, the mare belonging to player Adolfo Cambiaso and one of the most important in the history of polo, who had died in May of that year.

CREDIT: PHOTO BY SEBASTIÁN LÓPEZ BRACH FOR THE WASHINGTON POST VIA GETTY IMAGES

At first, the results were not encouraging. The first clones by Vichera’s company, Kheiron Biotech, between 2012 and 2016, were made from adult skin cells, and almost half of the foals from the 38 live births had abnormalities of the umbilical cord or placenta, or limbs that were abnormally bent. The turning point came when the company started working with stem cells from bone marrow. “This technology changed everything. Today, almost 100 percent of births are as healthy as those obtained through natural breeding,” says Vichera. To date, Kheiron Biotech reports having produced a thousand cloned horses.

With the cloning technique now mastered, Kheiron Biotech ventured into even more ambitious territory. In December 2024, the company announced the birth of five foals that had been genetically edited using the CRISPR-Cas9 technique, a global milestone in equine breeding. The intervention consisted of inserting a DNA sequence known as SINE into the control sequences of the creatures’ myostatin gene. This is a genetic variant that already exists naturally in some breeds and influences muscle development. The main goal, however, was to demonstrate that precision genetic editing in horses is technically feasible, and compatible with cloning,

Vichera presented the achievement as proof of concept and a preview of a scenario in which it will be possible not only to copy the best horses, but also to introduce specific modifications to their genomes. Editing the myostatin gene has known effects on muscle fiber composition and performance during short, intense efforts, and there is ongoing research into other genes and possible applications, although the details have not been revealed.

With polo as its flagship, Argentina overwhelmingly dominates the global equine cloning industry, followed — at a considerable distance — by the United States and some European countries.

But despite the technical advances, significant losses occur at each stage. It is estimated that, out of every 100 embryos, 20 reach the blastocyst stage and are transferred. Of these, 10 are successfully implanted in surrogate mares, and of those 10, only five reach full term. Even among foals born, there can be problems with health and development, although the lack of public data prevents this from being quantified accurately.

The high loss rate partly explains the high cost of the procedure. Although the price has fallen in recent years thanks to technical advances, cloning a horse remains a luxury: It costs around $40,000 per born animal.

A taxidermy of Dolly the sheep at the National Museum of Scotland. Dolly was the first mammal cloned from an adult somatic cell. Born in Scotland, her case marked a turning point in reproductive biology and sparked scientific and ethical debates around the world.

CREDIT: SGERBIC / WIKIMEDIA COMMONS

Cambiaso’s dream come true

Shortly after Cambiaso requested that tissue from his horse Aiken Cura be preserved following the animal’s devastating fall and euthanasia, he launched Crestview Genetics, founded with Texas oilman Alan Meeker and Argentine businessman Ernesto Gutiérrez. In Texas, the company partnered with the firm ViaGen to begin the cloning work.

In August 2010 — four years after the accident that killed Aiken Cura — Cambiaso was in Santa Barbara, California, when he received a call with the news that the first clones of Aiken Cura and those of his mare Cuartetera had been born. He traveled immediately to see them. “It was a strange feeling,” he recalls. “We spent two hours looking at them, unable to believe it.”

Fabricio García, one of Argentina’s leading dressage experts, worked with these first young clones. “For me, it was the same as breaking in a normal colt. My boss [Cambiaso] told me, ‘Do your training, I like your training.’ The pressure was on, because they were the first clones, but then I realized they were horses like any other,” he says.

Training is the basis of everything, adds García, like the foundation of a house. As the years go by, the colt gets used to contact with the saddle and reins. Then it is guided through turns, stops and starts until it learns to respond precisely to the rider’s commands. In general, horses are ready to compete at six years of age, but the Cuarteteras — all clones — started with an obvious genetic advantage that allowed them to jump onto the field earlier.

The final of the 2016 Palermo Open would leave an unforgettable image. The original Cuartetera had retired a year earlier, but on the field, lined up by Cambiaso, were six identical mares — chestnut, slender, with a distinctive white spot illuminating their foreheads, all clones of Cuartetera — who would bring victory to La Dolfina. For the first time, clones were playing polo. Their names: Cuartetera B01, Cuartetera B02, Cuartetera B03, Cuartetera B04, Cuartetera B05, and Cuartetera B06.

That image — six cloned mares deciding the most important tournament in world polo — sparked a debate off the field. As equine cloning ceased to be an experimental rarity and became a competitive tool, ethical questions intensified: about the morality of standardizing of animals, and the biological costs of the process, especially for the recipient mares.

“We can talk about identity in any individual, even cloned horses,” says Finnish philosopher Häyry Matti, who specializes in ethics. “Improving the athletic performance of a nonhuman for human entertainment is repugnant. It intensifies objectification, manipulation and hegemonic imposition.”

Indeed, in the daily practice of cloning, dilemmas about animal welfare and objectification translate into procedures and risks that are rarely visible to the public and for which there are often no public records. According to equine geneticist Demyda Peyrás, “many clones are not born in the field, but in specialized veterinary hospitals or in the companies’ own neonatal units due to frequent complications during birth.” These, he adds, are rare in traditional horse breeding.

The ethical debate surrounding equine cloning has changed over the years. In the beginning, the main concern revolved around the health of the clones: malformations and potential suffering during gestation and adulthood. With technical advances and the standardization of protocols, these objections lost their centrality and, at least in the field of polo, the practice began to enjoy relative acceptance. However, this normalization did not dispel all worries. Concerns remain about the actual rate of miscarriages, health problems in foals born and, above all, the lack of transparency and public data to assess the biological impacts of the process.

Pablo Ross, scientific director of STgenetics, argues that today, cloning does not differ substantially from other reproductive technologies applied in animal breeding. Demyda Peyrás, on the other hand, warns of the risk of inbreeding depression, the loss of genetic variability when crossing individuals that are too closely related. The cloning industry relies almost exclusively on lines of the “Polo Argentino” breed and racehorses. If this trend continues, it could have an impact on the fertility and resilience of animals, and their ability to tolerate stress.

In turn, the combination of cloning and gene editing opens up new dilemmas, says Gambini, the University of Queensland veterinarian who specializes in reproductive biotechnologies. It is one thing to use such tools to prevent disease or improve production efficiency — which could be justified on welfare grounds — and quite another to use them to enhance athletic performance for human entertainment. The risks of editing, such as unwanted health effects on the animals, are still uncertain, which is why geneticists like Demyda Peyrás agree on the value of international regulations and the need for mandatory and detailed reporting systems on the development and health of genetically modified animals.

For his part, Cambiaso has always been impervious to questioning. From day one, he has defended a utilitarian view. He sees no ethical dilemmas and justifies the practice because of the benefits it brings to his game. He is driven by sporting glory and the consolidation of an industry that he himself started — an industry operating without public reporting systems that this year recorded the birth of 600 to 700 cloned horses in Argentina alone and has already cloned 60 Cuarteteras.

Article translated by Debbie Ponchner

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Maximiliano Fernández is a journalist who has been writing and editing stories on science, education and technology for 10 years. He is based in Buenos Aires, Argentina. You can contact him in LinkedIn.

HEALTH & DISEASE | VIEW ON WEBSITE

Beating back the Aedes aegypti mosquito

Scientists are taking a multipronged approach to tackle this dangerous carrier of dengue, yellow fever and other noxious viruses

By Katarina Zimmer    01.12.2026

Lea en español

Deep in northwestern Africa, a high-pitched hum pierces the moist forest. It is the mosquito Aedes aegypti, laying its eggs inside water-filled tree holes and feeding on various animals, posing little danger to any person it encounters.

But that is a scene from the distant past. Everything changed about 5,000 years ago, scientists reckon, when the African climate shifted, and this area — the Sahel — like the Sahara region farther north, became a drier place. Even A. aegypti, whose eggs can dry out and survive for months, couldn’t tolerate nine months of hot, dry weather every year.

What happened next turned the mosquito into a scourge.

Luckily for the insects, people — who up until then had lived nomadic lifestyles — began to settle down and to domesticate crops. They used clay pots to store and transport water — unwittingly providing a year-round, reliable habitat for eggs and juvenile mosquitoes. It meant mosquitoes could continue to exist in this region, as long as they stuck around humans.

In fact, being around people proved so beneficial to Aedes aegypti’s survival, scientists believe, that its antennae evolved to react more strongly to human odors than to those of other animals.

Aedes mosquitoes like Aedes aegypti have spread around the world in part due to their rapid life cycle and ability to reproduce in virtually any kind of water-holding container.

A preference for biting humans helped to ensure that, after a female mosquito consumed human blood and was ready to lay her eggs, there would always be a manmade source of water nearby, says Princeton evolutionary biologist Carolyn McBride. And so Aedes aegypti followed people and their containers everywhere — out of Africa, hitching rides in the water-storing vessels on early slave ships; around the world, through global trade; in used car tires, which fill easily with water. “It loves breeding in old tires,” says McBride.

The prolific rise of Aedes aegypti — and to some degree its less human-specialized cousin, Aedes albopictus — has allowed tropical diseases like dengue to spread globally. The dengue virus, and others like chikungunya, Zika and yellow fever, kill tens of thousands of people in tropical countries every year. The ramifications for human health became clearer than ever in 2024, which saw the world’s deadliest dengue season unfold, especially in South and Central America and Southeast Asia, with more than 14 million global cases and over 12,000 dengue-related deaths worldwide.

Experts worry that the trend could worsen as international travel, trade, urbanization and climate change continue to pull the insects into new areas, including Europe and the United States. One 2024 study estimated that, for each additional degree Celsius the planet warms, dengue cases in parts of Africa could increase by 10.5 percent.

The expansion of the mosquito Aedes aegypti across the tropics has facilitated the spread of a virus that causes the deadly disease dengue; this map shows the number of dengue cases between November 2024 and October 2025. Experts blame 2024’s dengue uptick on a variety of factors, not least a wetter and hotter climate that year. They expect that climate change and urbanization will cause the warmth-loving mosquito to increasingly colonize temperate regions, including Europe and North America.

That’s why scientists have been busy developing and testing new methods, from new vaccines to insect-infecting bacteria, for combating Aedes aegypti  and the diseases it carries. “Having this mix of tools that we know work is a situation we’ve not been in before, and gives us hope that we can reverse or at least limit some of these potential future increases,” says Oliver Brady, an epidemiologist at the London School of Hygiene and Tropical Medicine who studies the spread of mosquito-transmitted viruses.

The ‘perfect mosquito’

Aedes aegypti  is the “perfect mosquito” to spread disease, says mosquito expert Cameron Webb of New South Wales Health Pathology, an Australian forensics and diagnostics provider. While most mosquitoes take only one big blood meal to start making eggs, Aedes aegypti often enjoys multiple courses from different people. And, for reasons that scientists are still trying to understand, Aedes aegypti and Aedes albopictus are much more prone than other mosquito species to getting infected by viruses like dengue and chikungunya, which then stick around and multiply in the insects’ bodies. After a mosquito is infected, “it will remain infected for the rest of its life,” passing on viruses to new people with every bite, says virologist Louis Lambrechts of France’s Pasteur Institute.

Dengue and chikungunya (which can be misdiagnosed as dengue) are actually relatively easy to treat, says André Ribas Freitas, a physician and researcher at the São Leopoldo Mandic university campus in Campinas, Brazil. Most people survive the mild symptoms such as headaches, fever, muscle pain and skin rashes. When people die of dengue, it’s usually because of an extreme drop in blood pressure that happens when blood vessels become leaky, or because the infection spreads to the heart, brain and liver. These complications require careful administration of fluids and intensive care and life support. But in places like Brazil, for instance, which saw roughly 6,000 deaths in 2024, many densely populated areas don’t have enough health care facilities and experienced doctors, and emergency rooms in large cities like Campinas became overwhelmed, Freitas says. “It’s too many patients, and the treatment needs good and attentive care.”

Tropical countries such as Pakistan have been hard hit by dengue, a disease that can require intensive care and life support. Here, patients are covered by netting to prevent further bites from mosquitoes.

CREDIT: ZUBAIR MUNA / SHUTTERSTOCK

Curiously, the most severe dengue infections often happen upon people’s second encounter with the virus. Scientists believe this is because dengue is not one virus but actually four different subtypes. Each one looks very different to our immune system — so different that suffering an infection with one type doesn’t necessarily protect against another. But the immune system’s reaction to the virus can actually make the second infection worse. With a first-time dengue infection, “you don’t even see the symptoms. But the secondary one, it can become lethal,” says Navin Khanna, a dengue researcher based in New Delhi at the International Centre for Genetic Engineering and Biotechnology.

To many experts, the rise in cases underscores that traditional methods of preventing disease outbreaks aren’t sufficient. Window screens can impede airflow and are expensive; repellents aren’t affordable to most people; mosquito nets don’t work against day-biting Aedes mosquitoes, unlike night-biting Anopheles mosquitoes that transmit malaria. Many governments send officials into towns and cities to go door-to-door to manage water-holding containers or apply larva-killing substances, such as the chemical temephos, or to fumigate with insect-killing chemicals like pyrethroids during disease outbreaks.

But mosquitoes have evolved resistance to some insecticides, says Amy Morrison, a dengue and Aedes expert at the University of California, Davis, who is based in Iquitos, Peru. There, as in many other places including Brazil and Colombia, temephos and pyrethroids are “off the table now,” she says. And not all communities and individual houses are visited or treated regularly enough to put a dent in mosquito populations. In Iquitos, for instance, effective insecticide treatment would mean visiting more than 90,000 households, spraying for over two minutes in each household, on three occasions one week apart. “Some governments don’t have resources to do much of anything,” Morrison says.

Morrison has found promising results for new methods that have a longer-lasting mosquito-killing effect — such as targeted indoor residual sprays, which put long-lasting insecticides in places where mosquitoes rest, and repellents released into the indoor air to deter mosquitoes. But the challenge is regular and strategic implementation, she says. “It’s an endless battle.”

The problem gets stickier when looking beyond households. Aedes aegypti can lay eggs in anything from empty coffee cups and tuna cans to drains and rainwater tanks. And each female lays its eggs in multiple places in order to maximize the chances of the eggs hatching. Reducing breeding opportunities for mosquitoes requires infrastructure solutions — improved waste disposal systems, regular treatment of standing water with insecticides, or strategies to populate pools with larva-gobbling fish. But even in wealthy countries, “it comes with a price tag that is sometimes difficult to manage,” Webb says.

In many tropical countries such as Brazil, locals fumigate areas with insecticides to kill off mosquitoes during outbreaks of mosquito-borne diseases like Zika.

CREDIT: ISTOCK.COM / LUIZSOUZARJ

A vaccine conundrum

Where traditional control methods are lacking or ineffective, Freitas sees hope in vaccines against Aedes-borne diseases. These are typically based on weakened or modified viruses or virus-like particles that trigger the body’s immune system to generate antibodies that stick to certain proteins on the virus’s surface, stopping it in its tracks.

The approach proved effective back in the 1930s in developing a vaccine against yellow fever that has been saving lives ever since. A 2021 study estimated that, between 2005 and 2018, mass vaccination campaigns decreased the number of yellow fever outbreaks in 11 African countries by 34 percent. Research recently also delivered two vaccines for chikungunya, the first of which has been administered to tens of thousands of people globally.

There is still no vaccine for Zika — following a burst of infections roughly 10 years ago that caused thousands of birth defects in babies when their mothers contracted it during pregnancy, the virus has become too rare for the large-scale trials required to assess safety and efficacy of a vaccine, says Annelies Wilder-Smith, an infectious disease expert at the London School of Hygiene and Tropical Medicine.

But the greatest challenge, experts agree, is making a vaccine for dengue. “A dengue vaccine is clearly not for the faint of heart,” says Wilder-Smith.

That became apparent when the pharmaceutical company Sanofi, after 20 years of development, trialed the vaccine Dengvaxia in more than 35,000 children in Southeast Asia and Latin America. While the vaccine initially showed promise in protecting many of them against dengue, according to those trials, scientists also reported an alarming observation: In children between 2 and 16 years of age who had never had a dengue infection, receiving the vaccine later led to more severe dengue infections and a higher likelihood of hospitalization than was seen in unvaccinated children.

Scientists believe this happened because the vaccine effectively acted like a first-time infection with dengue — making the second, actual, infection worse. The severity of second-time dengue infections likely has to do with the fact that the various dengue subtypes have different proteins studded on their surfaces. Because of this, antibodies against one dengue subtype don’t effectively block the ability of the other subtypes to enter human cells. But many of the antibodies still end up sticking in places on the virus, forming large tangles of molecules that, along with the virus itself, are taken up by immune cells. The viruses then act like Trojan horses, killing these immune cells and reproducing, spreading and wreaking havoc, Khanna says.

In 2022 a second vaccine, Qdenga, was introduced. It showed fewer safety issues, but it doesn’t fully protect people against all dengue subtypes and is less effective in people who haven’t contracted dengue before getting vaccinated, Wilder-Smith says. A third vaccine, still being tested, also doesn’t seem to provide full protection, she adds. Like Dengvaxia and Qdenga, it may prove useful in people who previously have been infected with dengue, she says. “In the absence of a perfect vaccine, you use what you have.”

Researchers are finding clues on how to build more effective vaccines. Khanna, for instance, recently reported promising results in mice when testing a vaccine that is designed to elicit only virus-blocking antibodies for each dengue subtype without triggering those troublesome virus-helping ones — an approach that, in principle, would protect everyone against all dengue subtypes. “That would be a game changer,” Morrison says.

Bacteria versus mosquitoes

Scientists are also working on ways to take aim at the mosquitoes themselves, by harnessing bacteria called Wolbachia that inhabit the bodies of many insect species. Many such bacteria have the curious effect of killing their host’s offspring should males hosting Wolbachia mate with Wolbachia-lacking females. Scientists recently worked out why this happens: The male’s sperm becomes loaded with toxins made by Wolbachia, and these kill the resulting embryos unless the females also carry Wolbachia, along with the toxin’s antidote.

As early as the 1960s, scientists began to wonder: If they could get Wolbachia to infect mosquitoes, might the bacteria act as a kind of natural insecticide? Fast forward a few decades, and several companies are now raising Wolbachia-infected males by the millions; in the wild, these mate with uninfected females, killing the resulting offspring and suppressing local mosquito populations.

The trouble with this approach, though, is that mosquito populations quickly bounce back when the infected males die out, meaning that scientists need to keep releasing new ones. While that’s a sustainable business model in regions with enough resources to pay for continuous releases — like parts of the United States and countries like Singapore — it’s less feasible for the lower- and middle-income countries that are hardest hit by dengue, says evolutionary biologist Michael Turelli of UC Davis.

But scientists have discovered other ways of wielding Wolbachia to their advantage. In the early 2000s, researchers in the United Kingdom discovered in fruit flies that a certain strain of Wolbachia called wMel seems to make the insects resistant to particular viruses. Turelli suspects that, inside insect cells, wMel competes for the same resources, like protein-building molecules, that viruses also need to thrive. And because wMel is much better at acquiring these resources than the viruses are, it hampers the ability of the viruses to multiply. When scientists infected Aedes aegypti with wMel, this seemed to make the dengue virus less likely to reach the insects’ salivary glands. The result: “They’re going to bite you, but they’re not going to give you a horrible disease,” Turelli says.

The not-for-profit World Mosquito Program has built on this idea, releasing wMel-infected males and females into the wild. The infected females reliably spread wMel Wolbachia to their offspring, making them unable to transmit disease. Meanwhile, when infected males mate with wild, Wolbachia-less females, their offspring die, helping to ensure that only Wolbachia-infected young survive.

A man checks on a cup containing Wolbachia-infected mosquitoes which produce progeny that are less likely to carry diseases like dengue; the World Mosquito Program distributes such containers around disease-affected communities. After staff and volunteers add eggs of Wolbachia-infected mosquitoes, along with water and nutrients, the eggs hatch and develop into adults.

CREDIT: WORLD MOSQUITO PROGRAM

The program has tested the mosquitoes in 15 countries — including Brazil, Indonesia, Colombia, and Kiribati — with the buy-in of communities where they’re released, says Nelson Grisales, a medical entomologist with the program. This has already put a dent in disease transmission, for instance in Yogyakarta, Indonesia, where scientists counted 86 percent fewer dengue hospitalizations in areas with Wolbachia-carrying mosquitoes compared to Wolbachia-free areas. And in contrast to vaccines, which may not be accessible or affordable to everyone, Wolbachia “will protect anyone who is in the territory,” Grisales says.

To ramp up the effort, the World Mosquito Program recently partnered with the Oswaldo Cruz Foundation, a Brazilian scientific institution, and Brazil’s Institute of Molecular Biology of Paraná to build Wolbito do Brasil, the world’s largest mosquito breeding facility, in the city of Curitiba. In a statement, the facility’s chief executive said it has the capability of churning out 100 million wMel-infected mosquito eggs every week.

But the Wolbachia strategy may not work everywhere. For one, it seems to be less effective in places that see long periods of temperatures over 104 degrees Fahrenheit, due to reduced Wolbachia survival. And even where Wolbachia can be reliably introduced, the mosquito populations will require long-term monitoring — and potentially additional releases — to ensure that they’re effective. One long-term concern is that the viruses could evolve ways of outsmarting their Wolbachia neighbors, Turelli says.

There are other biological strategies that scientists are working on, including genetically engineering Aedes aegypti mosquitoes so that their female offspring are unable to fly, or so that offspring are only male — and, ultimately, quashing mosquito populations.

Indeed, experts agree it’s only through a combination of tools that Aedes aegypti -borne diseases can be suppressed. These methods will prove increasingly important as the viruses continue to spread, and if new ones spill over into human populations; Zika, chikungunya, dengue and yellow fever are thought to have originated in African forests, where many such viruses circulate among wild animal populations. Just as it was people who spread Aedes aegypti around the world, so it is human actions — new technologies, smart planning and good foresight — that can make the buzzing, biting and spreading insects less dangerous for everyone.

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Katarina Zimmer is a science and environment journalist based in Germany. She is a special contributor to Knowable Magazine, where she covers the energy transition and planetary health. Her other work is published in National Geographic, Scientific American, BBC Future and elsewhere. Check out more of her work at www.katarinazimmer.com.

SOCIETY | VIEW ON WEBSITE

Top science stories of 2025

In a year of funding chaos, ongoing climate change and pollution perils, we also saw the most powerful telescope yet, personalized gene therapy, and the next-best-thing to an HIV vaccine — not to mention a brand-new color

By Nicola Jones    12.22.2025

Lea en español

2025 was a year of turmoil for many scientists — particularly in the United States, where job cuts and budget slashing has left many reeling. But it was also a year of promising advances in fields from gene therapy to quantum computing.

In the US, executive orders by President Donald Trump led to the loss of thousands of jobs in government agencies, including NASA, which oversees space exploration, and NOAA, which runs the National Weather Service among other vital activities. Thousands of health-related research grants — especially those with any perceived link to diversity, equity and inclusion — were canceled or withheld. And Harvard and other universities saw billions of dollars held back, at least temporarily.

Trump’s budget proposal for 2026 (the US budget had not been finalized as Knowable Magazine went to press) features huge cuts to science funding, including slicing the budget for the National Science Foundation, the main granting agency for basic science research, in half. And cuts that have already been made spell bad news for global efforts to quash diseases and keep climate change in check.

Amid all the bad news, there have also been lives saved, technologies advanced and some very weird science conducted. Here are some of the things that captured Knowable’s attention in 2025.

Vaccine hits and misses

Public health faced big challenges this year. “There have been enormous changes in 2025, really driven by the current [US] administration and their attitude towards both foreign aid and domestic vaccine policy,” says epidemiologist William Moss at the Johns Hopkins Bloomberg School of Public Health and coauthor of an Annual Review of Public Health article on global vaccinations. The US withdrew from the World Health Organization (WHO) in 2025, for example, and said it would pull funding from Gavi, the Vaccine Alliance.

Experts are worried that increasing gaps in vaccination coverage will contribute to further outbreaks of infectious diseases previously thought to be under control. This year, for example, measles surged in North America: Canada lost its “measles elimination” status in November, with cases much higher than anything seen in decades, and the US may follow in 2026. Whooping cough is also on the rise.

Over the past 50 years, immunization has saved an estimated 154 million lives globally. Maintaining that is proving hard. The 2020 pandemic caused disruptions to vaccination campaigns, and many have not yet recovered to pre-pandemic levels. Part of the problem is growing anti-vax sentiments. In the United States, vaccine coverage in kindergartners has crept downward from around 95 percent to 92 percent over the past dozen years, with exemptions from one or more recommended vaccines reaching a record high of 3.6 percent in the 2024-25 school year. These trends could signal trouble ahead.

Experts are worried that increasing gaps in vaccination coverage will contribute to further outbreaks of infectious diseases previously thought to be under control.

There is some good news. After three years of negotiation, delegates to the WHO (not including the US) adopted a Pandemic Agreement with a better system for equitably sharing vaccines and drugs. Coverage with the HPV (human papillomavirus) vaccine, which protects against the sexually transmitted virus that causes cervical cancer in women and some throat cancers in men, continues to increase. And despite the cancellation of $500 million in funding for messenger RNA (mRNA) research in the United States, researchers are increasingly enthusiastic about mRNA vaccines, following on their success during the Covid-19 pandemic. Early research suggests that mRNA vaccines could be particularly promising in the fight against cancer.

HIV hope — and setbacks

This year saw some good news on the HIV front. Experimental infusions of neutralizing antibodies allowed some people with HIV to achieve remissions lasting months or years without the usual daily doses of antiretroviral drugs. And in July, the WHO endorsed twice-a-year injections of a long-lasting, highly effective injectable drug called lenacapavir for HIV prevention, following on the heels of US approval for that use. Experts say this marks a momentous shift for people at risk of HIV. WHO Director-General Tedros Adhanom Ghebreyesus said: “While an HIV vaccine remains elusive, lenacapavir is the next best thing.”

These new treatments may be especially valuable given the Trump administration’s decision this year to dismantle programs run by the US Agency for International Development (USAID). This includes the disruptions to the President’s Emergency Plan for AIDS Relief (PEPFAR) that delivered a huge and shocking blow to the global HIV/AIDS effort this year. As a result, the United Nations effort UNAIDS — to which USAID used to be the largest donor — could be shuttered in 2026, four years ahead of schedule.

All this has left experts and advocates reeling, as the number of people living with HIV — still one of the world’s most deadly viruses — continues to climb. UNAIDS predicts that if the PEPFAR funds permanently disappear, there could be over 6 million additional HIV infections and an additional 4 million AIDS-related deaths by 2029. “The sudden withdrawal of lifesaving support is having a devastating impact,” said UNAIDS Executive Director Winnie Byanyima at a press briefing in March. “It is very serious.”

UNAIDS executive director Winnie Byanyima says her organization has lost huge chunks of its usual funding, leaving the HIV global response in crisis.

CREDIT: ROMAN LEVCHKENKO / UNAIDS VIA AP

Spectacular space advances

Astronomers rejoiced as the new Vera C. Rubin Observatory, built atop a mountain in Chile, came online this year. The telescope hosts the world’s biggest camera, at 3.2 billion pixels, and is expected to gather more data in its first year than all previous optical telescopes combined. The project aims to catalog some 5 million asteroids, including 100,000 near-Earth objects, over the next decade. It will also help to study dark matter and objects such as supernovae, and pursue new discoveries, including optical signals of gravitational waves. “The Rubin Observatory promises to impact virtually every area of astronomy and astrophysics, often profoundly,” says astronomer Robert Kennicutt at the University of Arizona, coeditor of the Annual Review of Astronomy and Astrophysics.

Among the more unusual targets that Rubin will help to spot are interstellar objects — hunks of rock or ice blasting through our solar system from elsewhere. So far, astronomers have only detected three such objects, including 3I/ATLAS, which made its closest approach to Earth in December. It is suspected that there are many more to find; Rubin could spot dozens over the next decade.

The Vera C. Rubin Observatory in Chile opened its eyes to the southern skies this year, capturing millions of galaxies and thousands of asteroids in its first 10 hours of test observations. Astronomers have high hopes for the telescope, which features the world’s biggest camera.

CREDIT: NSF–DOE RUBIN OBSERVATORY / NOIRLAB / SLAC / AURA / T. MATSOPOULOS

Personalized gene editing gets started

Since the first gene therapy treatment based on CRISPR — which uses molecular scissors to precisely cut and modify DNA — was approved in 2023 for sickle cell disease, efforts to develop other treatments have ramped up. Therapies are under investigation for a host of conditions including type 1 diabetes, various cancers and even high cholesterol.

But the big headline this year was the first personalized gene therapy: A baby boy with a life-threatening genetic condition became the first to receive a customized therapy, using a CRISPR-based technique that can precisely edit individual DNA letters. Personalized CRISPR treatments could allow doctors to effectively treat people suffering from rare or even unique life-threatening conditions. Such diseases collectively affect hundreds of millions of people worldwide.

In 2025, baby boy KJ Muldoon was the first individual to receive a personalized gene therapy treatment, for a potentially fatal condition that threatened his brain with toxic levels of ammonia. He recently took his first steps.

CREDIT: CHILDREN’S HOSPITAL OF PHILADELPHIA

The team behind the baby boy’s successful procedure announced this October their intention to try similar treatments in more children starting in 2026, and in November the Food and Drug Administration launched a new pathway to market for these procedures. A Center for Pediatric CRISPR Cures in California was also created in July to help families facing ultra-rare diseases. Funded by the Chan Zuckerberg Initiative, the center will be led by researchers at UC Berkeley and UC San Francisco. “I know firsthand the heartbreak of telling parents that we don’t understand their child’s illness or that we don’t know how to treat them,” Priscilla Chan, pediatrician and co-CEO of the Chan Zuckerberg Initiative, said in a press release about the new center.

Hopes raised for more transplants

This year brought important progress for xenotransplantation, the practice of using donor organs from pigs or other animals for people who need transplants. While only a handful of people have so far received pig hearts or kidneys — in special cases where they had no other options — those cases are blazing a trail toward making this technique a clinical reality. “The numbers are small but mighty,” says Joseph Ladowski, a surgeon and researcher in transplant immunology at Duke University.

This year brought several experimental transplants of pig organs (including the first lung), with one pig kidney lasting nearly nine months, a new record, before failing. Most important, in February the FDA green-lit the first multiperson trials of pig kidney transplants, which will allow doctors to standardize and optimize the technique. We should see half a dozen more transplants of animal organs in 2026, says Ladowski, with numbers ramping up steeply after that.

Another exciting development happening in parallel may also help ease the global shortage of donor organs: using an enzyme to convert the blood type of donated organs, removing antigens that can result in rejection in both human and animal transplants. In October, a team reported the first transplant of a human kidney that had its blood type converted from type A to universal donor type O.

Potential treatment for Huntington’s disease

This year researchers reported a small but promising study in which they slowed the progression of Huntington’s disease, an inherited disorder that gradually breaks down neurons, causing uncontrollable movements and a progressive degradation of behavior and thought. The treatment, by the Amsterdam-based company uniQure, is the first to address the disease itself rather than simply easing its symptoms.

Researchers engineered a harmless virus to deliver small molecules called microRNAs designed to block the action of the defective gene that causes Huntington’s. Then they infused the virus into targeted regions of the brains of 29 patients. In those who got the higher of two doses, the treatment slowed the progression of the disease by 75 percent, the team found. The result is “a remarkable step forward for patients and families,” says Andreas Keller, a bioinformatician at Saarland University in Germany who studies potential clinical applications of microRNAs. “This is a convincing proof-of-concept.”

As the climate crisis deepens, renewables get energized

This year continued the growing momentum of the renewable energy transition, thanks in large part to the plummeting cost of solar power. According to an October report from the think tank Ember, the first half of 2025 saw renewable energy provide more than a third of global electricity, squeaking ahead of coal for the first time.

But that’s rare good news in a grim climate picture. US policy, notably, is generally moving against renewable energy: In a speech to the United Nations in September, President Donald Trump said “If you don’t get away from the green energy scam your country is going to fail.”

2025 saw renewable energy provide more than a third of global electricity, squeaking ahead of coal for the first time.

Worldwide efforts to fight climate change are seriously off target, according to the UN Environment Programme. Global emissions of carbon dioxide may have declined slightly in 2025, but they need to be falling much faster if we are to hit our climate targets. Experts now say we will miss the goal of limiting the warming to 1.5 degrees Celsius, but action can still help to stave off catastrophic consequences to ecology and humankind. “Every small fraction of a degree matters,” says Diana Ürge-Vorsatz, an environmental scientist and climate expert at Central European University and vice chair of the Intergovernmental Panel on Climate Change. The latest data put 2025 as the second- or third-hottest year on record, after record-breaking 2024, with an annual average temperature about 1.48 degrees Celsius above the pre-industrial average.

Porous metals come of age

A class of materials called metal organic frameworks (MOFs) hit the headlines this year with Nobel Prize recognition, along with the first signs of commercial applications. MOFs are the world’s most porous materials: crystals of metal ions linked by long organic molecules. Their porosity could make these molecular sponges useful as storage containers for gases or drugs.

“MOFs are very elegant, scientifically, and highly versatile,” says Ram Seshadri, a chemist and materials scientist at UC Santa Barbara and editor of the Annual Review of Materials Research.

Although they have been a scientific curiosity for decades, MOFs are now starting to gain traction in applications — in part because artificial intelligence has massively sped up the hunt for new MOF formulations with desired properties, and in part because of increased interest in sucking carbon dioxide out of the air to fight climate change. This May, a company launched a new factory for making MOF sponges to capture carbon dioxide from ambient air. Others are investigating using MOFs to harvest water from the air in desert regions, store hydrogen gas to use as a zero-carbon fuel, and even deliver drugs within the body.

Metal organic frameworks — crystals of metal ions linked by long organic molecules, shown here in a model — are becoming commercially useful thanks to their record-breaking porosity.

CREDIT: PHOTO BY JONATHAN NACKSTRAND / AFP VIA GETTY IMAGES

Quantum computing gears up

Quantum computing made significant progress this year. Quantum computers are built from qubits, which exploit quantum behaviors to offer faster computation but are also inherently unstable and error prone. To make a practically useful quantum computer, designers have to create a multi-qubit system that produces a lower overall error rate than seen in the individual bits. There have been a few recent practical demonstrations of this “quantum error correction” process. And then in October, Google announced that its “quantum echoes” algorithm proved 13,000 times faster than a classical computer at predicting molecular structures — one of the first potentially practical applications.

That’s not the only quantum computing news this year. The 2025 Nobel Prize in physics went to some of the foundational research for quantum computing (fittingly, given that 2025 was also UNESCO’s International Year of Quantum Science and Technology). “Quantum computing is definitely accelerating,” says William Oliver, a quantum engineer at MIT. “It’s pretty exciting.”

Pollution perils stack up

The global effort to manage pollution faced big setbacks this year. In March, the US Environmental Protection Agency (EPA) announced more than 30 acts of deregulation, many aiming to remove controls it claims were “throttling” the oil and gas industries. In August, the EPA proposed rescinding its foundational 2009 Endangerment Finding, which concluded that greenhouse gas emissions are air pollutants that endanger public welfare. Rescinding the finding would eliminate the legal basis for the EPA’s climate-based regulations. A long list of rules being rolled back is being compiled by Harvard University’s environmental and energy law program, while the Natural Resources Defense Council is tracking canceled and frozen environmental funding.

On the international stage, a hoped-for treaty to end plastic pollution fell apart this summer as participants fought over the scope of what the treaty could reasonably cover and the strength of its promises. While negotiations are expected to resume at some point in the future, for now it is up to individual governments to set their own rules for reducing plastic pollution.

Meanwhile, controversial efforts to mine the ocean bottom for minerals took a step forward despite studies showing negative impacts of test mining on seafloor life. Mining in international waters falls under the purview of the International Seabed Authority, which is developing a Mining Code to regulate this activity. But in April, the Metals Company sidestepped this process by seeking a permit directly from the United States, which has not ratified the UN Convention on the Law of the Sea that governs the seabed authority. Trump issued an executive order in April to fast-track such mining applications. A final decision is still pending.

Mighty mitochondria: More than just powerhouses

The term “mitochondrial dysfunction” featured heavily in headlines this year as politicians and researchers alike leaned in to the idea that malfunctions of this subcellular structure may underlie chronic diseases ranging from Parkinson’s to cancer, diabetes and more. “It’s becoming more and more recognized that once you perturb mitochondria, a whole bunch of diseases can occur,” says Andrew Dillin, a molecular and cell biologist at the University of California, Berkeley.

Mitochondria, long called “the powerhouses of cells” because they convert nutrients into chemical fuel, turn out to do much more than that. In particular, these little structures inside our cells — which probably evolved from ancient bacteria — have retained their ancient abilities to communicate, making them a major hub for cell signaling and a big player in regulating stress, immunity and metabolism.

Mitochondria may be far more than just the powerhouses of our cells. Scientists now think they may influence many chronic diseases.

CREDIT: KATERYNA KON / SHUTTERSTOCK

Work this year showed that they can, for example, act as a “watchtower” against bacterial infection, detecting invading pathogens and helping the immune system mount a response. Mitochondria seem to be critical for memory formation in immune T cells, have an unexpected role in tissue healing, and might be targeted to help us live healthier for longer in old age.

And finally …

A couple of fun science stories that captured the world’s attention early this year are worth noting, even though some observers have poured cold water on the findings.

In April, Texas-based Colossal Biosciences announced it had genetically re-created dire wolves, a large-bodied wolf species that last roamed North America more than 11,000 years ago. To be precise, the company made 20 genetic tweaks to 14 locations in the genome of gray wolves. Debate erupted about whether this really amounts to re-creating dire wolves, which are thought to differ from gray wolves by about 12 million letters of DNA. (Most experts say no.)

Is the dire wolf back from the dead? Colossal Biosciences claimed to have brought back the dire wolf, a species that went extinct more than 10,000 years ago, by editing some of the genes in a related wolf’s genome to match those found in dire wolves. Dire or not, the effort produced some cute pups.

CREDIT: COLOSSAL BIOSCIENCES

The work “marks a technical achievement in genome editing and synthetic embryology,” wrote stem cell biologist Dusko Ilic from King’s College London in a commentary. But, he adds, “what has been achieved is not resurrection, but simulation.” Work continues to “de-extinct” other animals, from the dodo to the woolly mammoth. Whether this is achievable or desirable is a matter of opinion. Other genetic techniques are also being used to try to save living species on the brink of extinction, such as the northern white rhino.

Another quirky headline-grabbing story came when scientists made people see a color no one had ever experienced before. Researchers used a laser to directly stimulate just one of the three types of color-sensitive cone cells in the retina: the M cone, which is most sensitive to medium-wavelength light. That never happens in the real world, because any light that stimulates the M cone would also stimulate the neighboring S (short) and L (long) cones to some degree. The five people who experienced this odd light show said the result looked “green-blue,” a color dubbed “olo” by the researchers. The work is a fun exploration of the weird and wonderful world of color perception.

10.1146/knowable-122225-1

Nicola Jones is a freelance science journalist living in Pemberton, British Columbia.

FOOD & ENVIRONMENT | VIEW ON WEBSITE

The science of green hair care

A push to move away from petroleum products — plus the perception that natural is gentler — has scientists lathering up new ingredients, from wood and fungus extracts to engineered proteins

By Carolyn Wilke    12.18.2025

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Mika Sipponen, a materials chemist at Stockholm University, went for a swim in a murky lake. Afterwards, he noticed that his hair felt smooth — even without adding any hair product. The brownish water was rich in plant matter. So Sipponen wondered if one of the organic compounds — lignin, which is found in wood — could help to condition hair.

His team made a concoction of lignin blended with coconut oil — and it worked. Experiments showed that it smoothed the surface of hair shafts and reduced the force that it took to drag a comb through hair. And because lignin can be sourced from wood waste, Sipponen reasoned, hair products made from it would be more environmentally friendly than ones made with some of the standard ingredients.

Researchers made a hair conditioner using lignin derived from wood, and coconut oil. Untreated hair is shown at top (A). Bleached hair (B) was treated with the lignin conditioner or regular conditioner. Scanning electron microscopy images reveal that the lignin conditioner (C) smoothed the hair as well as the regular conditioner (D) and tests showed the concoction decreased the force needed to run a comb through the hair.

That research, published in Science Advances in 2025, is just one recent example of efforts to “green” hair care products, many of which have ingredients that are derived from non-renewable petrochemicals or that don’t degrade in the environment. The hair care market is worth tens of billions of dollars, and a growing number of consumers want products that have a smaller environmental footprint and are made from ingredients they perceive as being milder on the body. “Consumer awareness and pressure has made a real impact on the hair care market,” says Alexa Friedman, an epidemiologist at the Environmental Working Group in Washington, DC.

The result has been a hodgepodge of efforts to incorporate bio-based compounds into products, including lab-made proteins and promising molecules from plants, fungi and even insects.

Remodeling and repairing

It takes a lot of chemistry to make effective hair products — shampoos that foam and carry away dirt or conditioners that leave hair feeling smooth. An average head hosts 120,000 to 150,000 hairs. At around shoulder length, that mop top makes for some six square meters of surface area.

When people wash, condition and style their hair, they are spreading products across that large area — much of hair care is actually surface chemistry. It influences many characteristics of hair including luster, strength, softness and even the shapes that locks take.

Zoom in on that surface and a strand of hair looks like a shingled snake. Mechanical wear and tear from harsh brushing and chemical treatments can rough up hair’s overlapping scales and change its feel and behavior. A thin layer of lipids — fatty compounds — coats the outside of healthy hair, acting as the first line of defense and contributing to hair’s luster, while the interior is mostly protein, particularly a type of keratin.

Investigating the performance of hair care products can involve a contraption like the one shown above that measures the force required to run a comb through hair.

CREDIT: PHOTO OF A/HCR HAIR COMBING RIG COURTESY OF STABLE MICRO SYSTEMS, LTD.

Bio-inspired molecules that target keratin have already found their way into some products. An early keratin-repairing molecule came from the lab of biotechnologist Artur Cavaco-Paulo, who was investigating proteins that help the lungs expand, contract and exchange oxygen during breathing. In the lung lining, his team found protein fragments, or peptides, that seemed to have the right chemistry to stick to peptides associated with keratin, making them a candidate for hair repair.

His team ended up identifying around 1,200 promising peptides. Experiments showed that one of them finds and sticks to dangling ends of hair where bonds in the keratin have been broken. “It really reconnects those,” says Cavaco-Paulo, who works at the University of Minho in Braga, Portugal, and is CEO of Solfarcos, a company developing new applications of peptides and proteins for pharmaceuticals and cosmetics. In 2013, this peptide became part of the commercial product known today as K18; evidence suggests that it improves the strength of hair, especially before and after dyeing or other harsh treatments.

Now the researchers are looking to silk, skin and insects for new protein ingredients. In one effort, they designed a protein that borrows part of its structure from silk and part from elastin, a protein found in skin, and then engineered the bacterium E. coli to make the protein. Applying it to hair made the hair stronger and more elastic compared with untreated hair samples, the team reported in the October 2025 ACS Biomaterials Science & Engineering. The protein may find use in leave-in hair products or hair masks that help maintain hair health during perming. The scientists are also looking at molecules related to resilin, an elastic protein found in various insects, as a way to protect hair from heat and mechanical damage.

Cavaco-Paulo’s team has investigated other peptides from keratin that can straighten curly hair without harsh chemical treatments. And formulations based on cellulose — molecules abundant in plant cell walls — might be used to more gently curl hair; early research finds the effect lasts through three washes with shampoo. “We think that this might be the direction to take our research,” Cavaco-Paulo says. So far, however, the results from these biomolecules don’t match those produced by harsh chemicals like ammonium thioglycolate and lye that are traditionally used to perm or relax hair.

Washing and conditioning

Many hair care products, such as conditioners, contain long-chained molecules called polymers that smooth jagged edges on hair protein scales to reduce frizz. These polymers are often positively charged and stick to the negatively charged surface of damaged hair.

Although existing polymers work well, many are derived from petrochemicals. These include many polyquaternium compounds, a class of ammonium-based molecules that are favored for use in conditioners due to their positive charge. But used in hair products, they go down the drain and may build up in the environment. And some conditioners use synthetic polymers with a backbone of silicon. They make hair feel very smooth but microbes can’t easily degrade them, Cavaco-Paulo says; naturally made materials can break down more easily.

Lignin, which can be sourced from agricultural and lumber waste, is one such ingredient, says pharmacist Carla Varela of the University of Coimbra in Portugal. The polymer also has antibacterial activity and provides some protection from the sun’s ultraviolet rays, making it an attractive addition to hair products.

Scientists are looking to living things to source new molecules for hair products. Lignin from trees (top left) can help smooth damaged hair; engineered E. coli bacterium (top right) produces proteins based on silk and those in skin that can make hair stronger and more elastic. A material made from chitin, found in the walls of fungi such as Aspergillus niger (bottom right) could also help to condition hair. Other fungi, Candida species (bottom left), make molecules called sophorolipids that replace sulfates in some shampoos.

CREDITS CLOCKWISE FROM TOP LEFT: CLAUDIO BIESELE / UNSPLASH; THOMAS SIMONET / FLICKR; ALEXANDER KLEPNEV / WIKIMEDIA COMMONS; DJSPRING / WIKIMEDIA COMMONS

Using lignin extracted from acacia wood, Varela and colleagues modified the natural polymer to make it positively charged so that it sticks more easily to damaged hair. That also made it more soluble in water, which is key for use in conditioners. The approach, reported in Chemical Engineering Journal in October 2025, doesn’t entirely avoid petrochemicals, which are the source of the chemical modifier for lignin, but it’s a good step, says Varela.

Other researchers are investigating chitosan, a material derived from the shells of crustaceans and insects and the cell walls of fungi. Chitosan is easy to work with and doesn’t require harsh chemistry — it’s already found in some hair products as a heat protection and styling agent, says Eduardo Guzmán, a physical chemist at the Universidad Complutense de Madrid in Spain. To avoid harm to animals, fungal sources of chitosan are preferable, but fungal-derived chitosan molecules are too small to deposit well on hair. So Guzmán and colleagues are working to find the right formulations — by varying amounts of salt, for example, or tweaking the pH of the solution — to boost chitosan deposition.

Scientists are also looking for substitutes for sulfates, which give shampoos their sudsy foam and are key to removing sweat, oil, dirt and built-up product. The long, hydrophobic tails of these molecules are attracted to oils and form little spherical shells around dirt and oil, trapping them. The molecules’ negatively charged heads allow water to easily wash the dirt-filled shell away.

Sulfates have a bad reputation because they can be irritants for some consumers; plenty of sulfate-free shampoos are already on drugstore shelves. These include surfactants called sophorolipids that are sourced from fungi, which cleanse gently and are used in some baby shampoos. Other sulfate replacements include alkyl polyglucosides — starchy, fatty molecules derived from plants such as coconut and palm oils, and glucose from corn and potatoes.

Shampoos and conditioners can contain dozens of ingredients, and how these interact influences how well the products work, so researchers can’t typically just swap in one molecule for another. But because hair care products are so frequently used, changes that make them better for the environment could add up. After all, Varela says, “everyone washes their hair.”

Still, Friedman of the Environmental Working Group cautions that it’s hard to know how green a product is because there is little accountability for claims about various products. (The Environmental Working Group has a verified program for personal care products that’s trying to bring more transparency.) And even if a product uses bio-based materials from renewable sources, it might still harm the environment: Palm plantations planted where forest was clear-cut, for example, harms important habitat and can add to carbon emissions.

Even though consumers may seek greener alternatives, the most important criterion for them is still whether a product works. “The first thing is performance,” Cavaco-Paulo says. “That’s what people look for.” Scientists, in those murky ponds, forests and fungi, are looking too.

10.1146/knowable-121825-2

Carolyn Wilke is a Chicago-based freelance science journalist who covers archaeology, chemistry and the natural world.

PHYSICAL WORLD | VIEW ON WEBSITE

When clouds flock together

Scientists are discovering that clumping clouds supercharge storms in surprising ways — driving heavy, deadly rainfall and flooding

By Clare Watson    12.16.2025

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Caroline Muller looks at clouds differently than most people. Where others may see puffy marshmallows, wispy cotton candy or thunderous gray objects storming overhead, Muller sees fluids flowing through the sky. She visualizes how air rises and falls, warms and cools, and spirals and swirls to form clouds and create storms.

But the urgency with which Muller, a climate scientist at the Institute of Science and Technology Austria in Klosterneuburg, considers such atmospheric puzzles has surged in recent years. As our planet swelters with global warming, storms are becoming more intense, sometimes dumping two or even three times more rain than expected. Such was the case in Bahía Blanca, Argentina, in March 2025: Almost half the city’s yearly average rainfall fell in less than 12 hours, causing deadly floods.

Atmospheric scientists have long used computer simulations to track how the dynamics of air and moisture might produce varieties of storms. But existing models hadn’t fully explained the emergence of these fiercer storms. A roughly 200-year-old theory describes how warmer air holds more moisture than cooler air: an extra 7 percent for every degree Celsius of warming. But in models and weather observations, climate scientists have seen rainfall events far exceeding this expected increase. And those storms can lead to severe flooding when heavy rain falls on already saturated soils or follows humid heatwaves.

Clouds, and the way that they cluster, could help explain what’s going on.

A growing body of research, set in motion by Muller over a decade ago, is revealing several small-scale processes that climate models had previously overlooked. These processes influence how clouds form, congregate and persist in ways that may amplify heavy downpours and fuel larger, long-lasting storms. Clouds have an “internal life,” Muller says, “that can strengthen them or may help them stay alive longer.”

Other scientists need more convincing, because the computer simulations researchers use to study clouds reduce planet Earth to its simplest and smoothest form, retaining its essential physics but otherwise barely resembling the real world.

Now, though, a deeper understanding beckons. Higher-resolution global climate models can finally simulate clouds and the destructive storms they form on a planetary scale — giving scientists a more realistic picture. By better understanding clouds, researchers hope to improve their predictions of extreme rainfall, especially in the tropics where some of the most ferocious thunderstorms hit and where future rainfall projections are the most uncertain.

First clues to clumping clouds

All clouds form in moist, rising air. A mountain can propel air upwards; so, too, can a cold front. Clouds can also form through a process known as convection: the overturning of air in the atmosphere that starts when sunlight, warm land or balmy water heats air from below. As warm air rises, it cools, condensing the water vapor it carried upwards into raindrops. This condensation process also releases heat, which fuels churning storms.

But clouds remain one of the weakest links in climate models. That’s because the global climate models scientists use to simulate scenarios of future warming are far too coarse to capture the updrafts that give rise to clouds or to describe how they swirl in a storm — let alone to explain the microphysical processes controlling how much rain falls from them to Earth.

To try to resolve this problem, Muller and other like-minded scientists turned to simpler simulations of Earth’s climate that are able to model convection. In these artificial worlds, each the shape of a shallow box typically a few hundred kilometers across and tens of kilometers deep, the researchers tinkered with replica atmospheres to see if they could figure out how clouds behaved under different conditions.

The top frame of this computer simulation shows an atmosphere where the movements of air are somewhat disorganized, leading to clouds popping up in random locations. At the bottom is a simulation of an atmosphere where patterns of convection have become organized, and clouds spontaneously clump together into one large region — forming a storm.

CREDIT: CAROLINEMULLER123

Intriguingly, when researchers ran these models, the clouds spontaneously clumped together, even though the models had none of the features that usually push clouds together — no mountains, no wind, no Earthly spin or seasonal variations in sunlight. “Nobody knew why this was happening,” says Daniel Hernández Deckers, an atmospheric scientist at the National University of Colombia in Bogotá.

In 2012, Muller discovered a first clue: a process known as radiative cooling. The Sun’s heat that bounces off Earth’s surface radiates back into space, and where there are few clouds, more of that radiation escapes — cooling the air. The cool spots set up atmospheric flows that drive air toward cloudier regions — trapping more heat and forming more clouds. A follow-up study in 2018 showed that in these simulations, radiative cooling accelerated the formation of tropical cyclones. “That made us realize that to understand clouds, you have to look at the neighborhood as well — outside clouds,” Muller says.

Once scientists started looking not just outside clouds, but also underneath them and at their edges, they found other small-scale processes that help to explain why clouds flock together. The various processes, described by Muller and colleagues in the Annual Review of Fluid Mechanics, all bring or hold together pockets of warm, moist air so more clouds form in already-cloudy regions. These small-scale processes hadn’t been understood much before because they are often obscured by larger weather patterns.

Hernández Deckers has been studying one of the processes, called entrainment — the turbulent mixing of air at the edges of clouds. Most climate models represent clouds as a steady plume of rising air, but in reality “clouds are like a cauliflower,” he says. “You have a lot of turbulence, and you have these bubbles [of air] inside the clouds.” This mixing at the edges affects how clouds evolve and thunderstorms develop; it can weaken or strengthen storms in various ways, but, like radiative cooling, it encourages more clouds to form as a clump in regions that are already moist.

Such processes are likely to be most important in storms in Earth’s tropical regions, where there’s the most uncertainty about future rainfall. (That’s why Hernández Deckers, Muller and others tend to focus their studies there.) The tropics lack the cold fronts, jet streams and spiraling high- and low-pressure systems that dominate air flows at higher latitudes.

From the lower levels of the atmosphere to the higher regions known as the free troposphere, several phenomena help drive clouds to form and clump together. They include radiative cooling (1), in which solar heat bounces from Earth’s surface through clear skies back to space, causing cooling of parts of the atmosphere, as well as mixing (2) at clouds’ edges, which holds clouds together. Other processes (3 and 4) involve additional disturbances that can affect cloud behavior.

Supercharging heavy rains

There are other microscopic processes happening inside clouds that affect extreme rainfall, especially on shorter timescales. Moisture matters: Condensed droplets falling through moist, cloudy air don’t evaporate as much on their descent, so more water falls to the ground. Temperature matters too: When clouds form in warmer atmospheres, they produce less snow and more rain. Since raindrops fall faster than snowflakes, they evaporate less on their descent — producing, once again, more rain.

These factors also help explain why more rain can get squeezed from a cloud than the 7 percent rise per degree of warming predicted by the 200-year-old theory. “Essentially you get an extra kick … in our simulations, it was almost a doubling,” says Martin Singh, a climate scientist at Monash University in Melbourne, Australia.

Cloud clustering adds to this effect by holding warm, moist air together, so more rain droplets fall. One study by Muller and her collaborators found that clumping clouds intensify short-duration rainfall extremes by 30 to 70 percent, largely because raindrops evaporate less inside sodden clouds.

Other research, including a study led by Jiawei Bao, a postdoctoral researcher in Muller’s group, has likewise found that the microphysical processes going on inside clouds have a strong influence over fast, heavy downpours. These sudden downpours are intensifying much faster with climate change than protracted deluges, and often cause flash flooding.

The future of extreme rainfall

Scientists who study the clumping of clouds want to know how that behavior will change as the planet heats up — and what that will mean for incidences of heavy rainfall and flooding.

Some models suggest that clouds (and the convection that gives rise to them) will clump together more with global warming — and produce more rainfall extremes that often far exceed what theory predicts. But other simulations suggest that clouds will congregate less. “There seems to be still possibly a range of answers,” says Allison Wing, a climate scientist at Florida State University in Tallahassee who has compared various models.

Torrential rains in March 2025 flooded the city of Bahia Blanca, Argentina. Extreme precipitation like this is expected to become more common as the planet continues to warm, but predicting rainfall extremes in tropical regions is proving challenging.

CREDIT: PHOTO BY PABLO PRESTI / AFP VIA GETTY IMAGES

Scientists are beginning to try to reconcile some of these inconsistencies using powerful types of computer simulations called global storm-resolving models. These can capture the fine structures of clouds, thunderstorms and cyclones while also simulating the global climate. They bring a 50-fold leap in realism beyond the global climate models scientists generally use — but demand 30,000 times more computational power.

Using one such model in a paper published in 2024, Bao, Muller and their collaborators found that clouds in the tropics congregated more as temperatures increased — leading to less frequent storms but ones that were larger, lasted longer and, over the course of a day, dumped more rain than expected from theory.

But that work relied on just one model and simulated conditions from around one future timepoint — the year 2070. Scientists need to run longer simulations using more storm-resolving models, Bao says, but very few research teams can afford to run them. They are so computationally intensive that they are typically run at large centralized hubs, and scientists occasionally host “hackathons” to crunch through and share data.

Researchers also need more real-world observations to get at some of the biggest unknowns about clouds. Although a flurry of recent studies using satellite data linked the clustering of clouds to heavier rainfall in the tropics, there are large data gaps in many tropical regions. This weakens climate projections and leaves many countries ill-prepared. In June of 2025, floods and landslides in Venezuela and Colombia swept away buildings and killed at least a dozen people, but scientists don’t know what factors worsened these storms because the data are so paltry. “Nobody really knows, still, what triggered this,” Hernández Deckers says.

New, granular data are on their way. Wing is analyzing rainfall measurements from a German research vessel that traversed the tropical Atlantic Ocean for six weeks in 2024. The ship’s radar mapped clusters of convection associated with the storms it passed through, so the work should help researchers see how clouds organize over vast tracts of the ocean.

And an even more global view is on the horizon. The European Space Agency plans to launch two satellites in 2029 that will measure, among other things, near-surface winds that ruffle Earth’s oceans and skim mountaintops. Perhaps, scientists hope, the data these satellites beam back will finally provide a better grasp of clumping clouds and the heaviest rains that fall from them.

Research and interviews for this article were partly supported through a journalism residency funded by the Institute of Science & Technology Austria (ISTA). ISTA had no input into the story.

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Clare Watson is an Australian freelance science journalist and fact-checker who started out in biomedical research. Since trading pipettes for a pen, she has written for Undark, Nature, the Guardian, Hakai Magazine, Cosmos Magazine and Australian Geographic, and her work has been aired on ABC Radio National's Health Report. She also writes, edits and fact-checks for ScienceAlert.

HEALTH & DISEASE | VIEW ON WEBSITE

Progress fighting pancreatic cancer — one of the deadliest malignancies

Better outcomes may come from new drugs, strategies to rev up the immune system and learning to identify the disease sooner in its course

By Amber Dance    12.11.2025

Lea en español

A diagnosis of pancreatic cancer is devastating news. Though it makes up only about 3 percent of cancers in the United States, it’s one of the deadliest, and on track for a dark achievement: By 2030, it’s expected to kill more people in the United States than any cancer except for lung cancer. This apparent paradox is arising because screening and treatments for other cancers have surged ahead, while pancreatic cancer has remained tricky both to identify and to treat.

Nonetheless, there’s reason for hope, says Anna Berkenblit, chief scientific and medical officer for the Pancreatic Cancer Action Network in El Segundo, California, which supports research and helps patients. Scientists are testing new medicines that disable drivers of cancer that were once considered undruggable. They’re training patients’ immune systems to attack tumors once thought to be invisible to the body’s defenses. And they’re harnessing artificial intelligence to catch pancreatic cancer in early, vulnerable stages.

“The goal is to transform pancreatic cancer into a curable disease,” says Andrew Rakeman, vice president of research for the Lustgarten Foundation on Long Island, New York, which supports science on pancreatic cancer. Or, at least, “something that’s survivable, and livable, and can become more of a chronic condition.”

The five-year survival rate for pancreatic cancer is a dismal 13 percent. That’s partly because pancreatic tumors surround themselves in dense, scar-like tissue, blocking medicines and immune cells. Small tumors advance quickly but often go unnoticed until they’ve spread, making it too late for surgeons to remove all the cancer.

One of the biggest hopes right now is medicines that target a protein called KRAS, which is part of a cell’s growth-control machinery. In more than 90 percent of pancreatic cancers, mutated versions of KRAS get stuck in the “on” position, so cells divide uncontrollably.

Cancer biologists would love to shove a stick into the machinery of KRAS, but they’ve struggled to find a place to jam that stick. “People have described it to me as like a small, greasy ball … there’s no kind of pocket to stick an inhibitor in,” says cancer biologist Paige Ferguson of the Cold Spring Harbor Laboratory in New York, who cowrote an article about the challenges of treating pancreatic cancer in the 2025 Annual Review of Cancer Biology.

So researchers took a different tack: They were able to design a drug that attaches to a different cell protein. That drug/protein duo then grabs KRAS, stifling its dirty work. In an early trial, 38 people with pancreatic cancer receiving the drug, daraxonrasib, survived for more than eight months, on average, without their disease worsening. Treated patients also had less tumor DNA in their bloodstreams.

The drug’s developer, Revolution Medicines of Redwood City, California, is running a larger trial. Results are expected in mid-2026, but the US Food and Drug Administration has already offered a fast-tracked review.

Progress with vaccines

Another approach generating interest is vaccines. These therapeutic vaccines differ from the kinds that prevent infections — they are used in people who already have cancer, training the immune system to wipe out existing or recurring tumor cells.

As with regular vaccines, the cancer vaccine provides some molecule that the immune system sees as foreign and bad. In this case, that molecule is made by cancer cells, so the immune system should go after the cancer. The FDA approved the first therapeutic cancer vaccine, for prostate cancer, in 2010, and ones for different cancers are undergoing testing.

Pancreatic cancer resisted early attempts to rev up patients’ immune systems. “It has this amazing ability to keep the immune system out and tell the immune system to leave it alone,” says Rakeman.

The field of “immunotherapy” has yielded a variety of cancer treatments. This timeline highlights key progress on the road to vaccines that train the immune system to attack a cancer that is already present.

Part of the reason is the dense tissue surrounding the tumor “like a fort,” says Shubham Pant, a medical oncologist at the University of Texas MD Anderson Cancer Center in Houston. But if that fort and the tumor within are removed, the bits of cancer left behind should be unprotected. Pant and his colleagues reasoned that a vaccine might spur the immune system to mop up those remnants.

Working with Elicio Therapeutics of Boston, the scientists tested a vaccine containing bits of two mutant KRAS proteins. This, they hoped, would train the immune system to attack cancer cells containing those mutations.

The team ran a small trial that included 20 people with pancreatic cancer and five with colorectal cancer. Following surgery to remove the tumors, 21 people did generate immune T cells that were active against their cancers. And 17 patients with the greatest response “tended to do really well,” says Pant. The amount of tumor DNA in their bloodstreams dropped, and 13 remain alive more than three years after their first vaccine dose.

Encouraged, the team developed a vaccine against all seven common KRAS mutations. In a larger trial, they’re testing it in 158 people.

A different vaccine type has been tested at Memorial Sloan Kettering Cancer Center in New York. The scientists first took a close look at the few who live with pancreatic cancer beyond five years — fewer than one in 10 patients, says surgeon-scientist Vinod Balachandran, director of Sloan Kettering’s Olayan Center for Cancer Vaccines. They found that survivors were mounting immune responses to their cancers, but the immune cells weren’t going after mutant KRAS. They were responding to other weird proteins that show up in cancers because the cells make DNA-copying mistakes, creating random mutations. When these mutated proteins end up on the cancer cell surface, it’s a “red flag” to the immune system, says Balachandran.

Balachandran wanted to make this happen in more pancreatic cancer patients. So he and his colleagues provided trial participants with customized vaccines, matching their specific mutations, developed by BioNTech of Mainz, Germany, and Genentech of South San Francisco, California.

In early trials, the vaccines caused production of immune T cells against the mutant proteins in eight out of 16 patients, and the T cells persisted for years. Responders also went longer without recurrence of their cancer than non-responders. And all eight responders survived for at least two years after treatment. A larger, international, trial is underway.

Therapeutic cancer vaccines are based on mutations specific to an individual patient’s tumor. Once the tumor has been removed, scientists collect the cells and analyze their genes for mutations. They then create personalized vaccines informed by those mutations.

A push for early diagnosis

Another way to stymie pancreatic cancer would be to diagnose it early enough to remove the tumor before the cancer spreads.

Diagnostic companies like GRAIL of Menlo Park, California, aim to do this with pancreatic and other cancers by screening blood for tumor DNA. GRAIL revealed its latest results in October at the European Society for Medical Oncology Congress: Of 23,161 people age 50 or older, with no recent cancer, who were followed for at least a year, the test identified 133 with signs of cancer, including pancreatic cancer, that was later confirmed. About half of the correctly diagnosed cancers were early stage.

But the test also made mistakes, suggesting that 83 people had cancer when they didn’t. Even a very good test will give false positives, says Ferguson, and with pancreatic cancer so uncommon, widespread screening would yield many mistakes. So many physicians prefer to screen only high-risk individuals.

That group includes people with pancreatic abnormalities like cysts and those who carry cancer-linked mutations or have family members with pancreatic cancer, says Venkata Akshintala, a gastroenterologist and pancreatologist at Johns Hopkins Medicine in Baltimore. He’s an investigator on the long-running Cancer of the Pancreas Screening Study based at Johns Hopkins and other clinical centers. Its goal is to identify signs of early cancer in high-risk people, via DNA, pancreas secretions or imaging tests.

The screening seems to work. “We usually find cancer in the early stage,” says Akshintala. Of 1,731 CAPS participants, 19 were diagnosed while under surveillance. Their survival averaged nearly a decade, compared to 1.5 years for people who weren’t under surveillance when they got diagnosed, the researchers reported in 2022.

Participants in the CAPS surveillance program who were diagnosed with pancreatic cancer tended to be diagnosed at earlier stages of disease than people not in the active surveillance program (top). Those whose cancer or abnormal cells were detected in the surveillance program also had higher probability of survival than those diagnosed outside the surveillance program (bottom).

The Johns Hopkins researchers think there’s room for improvement by using AI to recognize patterns associated with pancreatic cancer in the mottled, black-and-white, endoscopic ultrasound patterns that gastroenterologists like Akshintala study for signs of early lesions. Combining AI with physician expertise resulted in more accurate predictions of a cancer progressing than either did alone, the team reported in 2024 at the Digestive Disease Week conference.

Back at MD Anderson, gastroenterologist Suresh Chari is studying another promising clue for early diagnosis of pancreatic cancer: recent blood-sugar test results that look like type 2 diabetes, often followed by unexpected weight loss. Normally, the pancreas controls blood sugar via release of hormones. But in this case, “the pancreatic cancer is causing your glucose metabolism to go crazy,” says Chari.

In a study of medical records, a risk score incorporating blood-sugar changes and weight loss correctly predicted pancreatic cancer in seven of nine people who went on to receive the cancer diagnosis, Chari and colleagues found. Most people who scored high didn’t have pancreatic cancer, Chari notes, but the screening narrowed the pool of folks who might benefit from further testing. Based on this research, he’s hoping to test a clinical approach in which those who score high get a one-time, AI-assisted CT scan within 15 days of their blood glucose results.

These tests and treatments in development could mean that pancreatic cancer won’t be one of the deadliest cancers forever. “Within the next 10 years,” says Berkenblit, “I think we’re going to see improved survival.”

Editor’s note: This article was amended on December 12, 2025, to clarify the contributions of BioNTech, as well as Genentech, in developing the general cancer-vaccine approach that surgeon-scientist Vinod Balachandran and colleagues tested in pancreatic cancer patients.

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Amber Dance is a freelance science journalist in the Los Angeles area and a special contributor for Knowable Magazine.

LIVING WORLD | VIEW ON WEBSITE

Comic

Journey to the egg: How sperm navigate the path to fertilization

COMIC: Male cells must survive twisty passages, strong currents and immune attacks; millions enter, but only one can finish

By Amber Dance Illustrated by Maki Naro    12.09.2025

10.1146/knowable-120925-1

Knowable contributor Amber Dance is an award-winning freelance science journalist in the Los Angeles area. She can’t draw.

Maki Naro is a feral cartoonist and science communicator. You can find his work at makinaro.com.

TECHNOLOGY | VIEW ON WEBSITE

Need laundry folded? Don’t ask a robot

For this chore, the human touch still beats machines. But maybe not for long.

By Kaia Glickman    12.04.2025

Lea en español

More than 60 years ago, Rosie the Robot made her TV debut in The Jetsons, seamlessly integrating herself into the Jetson household as she buzzed from room to room completing chores. Now, as reality catches up to science fiction and scientists work to develop modern-day Rosies, one of the most mundane tasks is proving to be a big challenge: folding laundry.

The ordinary-seeming act of picking up a T-shirt and folding it into a neat square requires a surprisingly complex understanding of how objects move in three dimensions. Our own ease in accomplishing such tasks comes from a learned understanding of how different fabrics will respond when folded, even if we haven’t folded them before, but robots struggle to apply what they learn to new situations that may differ from their training. As a result, current robots are slow and often perform poorly on even the simplest of folding tasks.

Now, however, newer approaches that adapt better to real-world scenarios may lay the groundwork for robots folding our laundry in the future.

A big challenge in teaching robots the skill is the infinity of ways that various fabrics can fold. Think about all the times you’ve tossed a T-shirt into the laundry basket and how it landed in a slightly different-shaped heap each time. It’s simple for people to pick up a shirt and quickly find a sleeve or collar to orient themselves, but every unique way a shirt crumples is a new challenge for robots, which are often trained on images of unwrinkled clothing lying flat on a surface, with all features visible.

“It’s not the fabric itself that is the challenge. It’s the amount of variations that can be created by the way fabric can be crumpled, and all the different kinds of clothing items that exist,” says David Held, a robotics researcher at Carnegie Mellon University in Pittsburgh.

Today’s robots often use a strategy called “pick and place,” in which the robot uses a pre-determined move to manipulate fabric. This often fails to result in a good fold, because soft fabric can crumple or distort unexpectedly.

CREDIT: A. LONGHINI ET AL / ADAFOLD: ADAPTING FOLDING TRAJECTORIES OF CLOTHS VIA FEEDBACK-LOOP MANIPULATION 2024

A newer folding algorithm, AdaFold, adjusts its folding path at each step to reduce crumpling and respond to dynamic changes in the fabric’s shape.

CREDIT: A. LONGHINI ET AL / ADAFOLD: ADAPTING FOLDING TRAJECTORIES OF CLOTHS VIA FEEDBACK-LOOP MANIPULATION 2024

That challenge is easier for people, because we are sensory sponges. Our eyes and hands provide a tremendous amount of information about the world through a lifetime of manipulating three-dimensional objects. Another result of all that learning is that simply looking at a piece of fabric gives us an intuition of how heavy or stretchy it is, and how it would best be folded. It’s clear to us that denim doesn’t fold like silk, for example, but robots don’t automatically understand that more force is required to lift and fold a pair of jeans than a delicate blouse and instead need to interact with the object before determining a folding plan.

Additionally, robots’ “hands” aren’t as versatile as ours. Many have grippers designed specifically for the size and shape of the object that’s going to be manipulated: A robot tasked to screw bolts into a panel of a car, for example, may have a gripper built to grab the exact size of the bolt. Laundry presents a challenge because the dimensions of fabric change with every maneuver, so grippers must be designed to adapt precisely to any shape and size of fabric.

“Humans have flexible hands covered by skin that can sense temperature, texture, whether something is wet or dry,” says Danica Kragic, a computer scientist at KTH Royal Institute of Technology in Sweden and coauthor of an article about robotic folding in the 2025 Annual Review of Control, Robotics, and Autonomous Systems. The long and short of it, Kragic says, is that “manipulating fabrics requires both advanced hand manipulation capabilities and high-level reasoning.”

Though robots often learn about the properties of real-world laundry by recognizing clothing features in images, more sophisticated approaches sometimes use physics to model fabric as a series of masses connected by springs, simulating the elastic nature of fabric. But even these representations often don’t capture the true complexity of clothing. Scientists are working to shrink this reality gap, as researchers term such issues, by developing better data sets. An example is ClothesNet, a collection of 4,400 simulated three-dimensional clothing items, with features such as sleeves and collars labeled, to provide a more realistic representation for robots to learn from.

Once they have been trained on a fabric’s properties, many robotic systems use a folding strategy called “pick and place,” where the robot uses computer vision technology to identify a specific point on a shirt (like the left sleeve), then pick up that point and place it down at a different specified point (perhaps the right sleeve). In these models, the origin, destination and trajectory of the maneuver is pre-determined based on assumed properties of the fabric, such as stretchiness and weight. Though it may sound straightforward, the approach limits the ability of robots to adapt to real-time changes in the environment — such as a pair of pants being far heavier than expected, or a button getting in the way. Should such things happen, the system can’t change its trajectory to complete a fold correctly.

Indeed, for this reason the results aren’t very good. Researchers often evaluate the success of a fold using a metric called Intersection over Union (IoU), essentially the amount of overlap of a material after it has been folded. A perfect fold would have an IoU score of 1, meaning the fabric was folded perfectly in half. In a 2024 study, pick and place scored a measly 0.41 when attempting to fold a rectangular piece of cloth in half.

Folding success is often scored using a method called Intersection over Union (IoU), which measures how fully the upper half of a fold covers the lower half. A perfect fold overlaps completely, giving an IoU of 1; the score is lower if one half doesn’t match the other.

New technologies aim to make robots better at reacting to real-time changes during a folding task. One of these approaches is called AdaFold (named for its adaptive folding abilities). Unlike pick and place, AdaFold can change its plan in the middle of a fold. The model repeatedly monitors the fabric as it’s folding to gauge progress, adapting to changes in cloth shape and elasticity and adjusting when necessary to ensure the most overlap when the fold is complete. In the same 2024 study, AdaFold scored an IoU of 0.83.

The dynamic, adaptable response shown by AdaFold could help researchers more broadly to design robots that respond flexibly to the ever-changing human world. “We have this capability of recognizing that our intuition was wrong — we can easily adjust our internal representation of the object,” says Alberta Longhini, cocreator of AdaFold and about to begin postdoctoral research at Stanford University in California. “For robots, this is still complex.”

Until roboticists solve that problem, it’s unlikely that we’ll be able to consign laundry or other daily chores to robots like Rosie. Alas.

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Kaia Glickman is a science journalist from Los Angeles. She’s getting her master’s degree in science communication from UC Santa Cruz, and is thrilled to have seen her first real live banana slug.

FOOD & ENVIRONMENT | VIEW ON WEBSITE

How plant-eaters snag their essential amino acids

Early in evolution, we animals lost the ability to manufacture nine of the 20 building blocks needed to make proteins. Herbivores evolved an impressive array of tricks to ensure their dietary needs are met.

By Katarina Zimmer    12.03.2025

Lea en español

In warm, shallow waters, a spiny, slug-like creature grazes on bacterial sludge on the seafloor, while sponges nearby filter clouds of suspended particles. A shell-encased Odaraia swims past, picking smaller life forms out of the water, while a giant Anomalocaris, with its formidable grasping appendages, prowls for soft-bodied critters. It’s a scene from some 500 million years ago, of oceans teeming with a new kind of life — the up-and-coming kingdom of animals.

Animals, made of many cells and feasting on other life instead of manufacturing their own nourishment from scratch, were an evolutionary hit. But this way of living brought complications. Early in the kingdom’s lineage, animals lost the ability to make nine of the 20 amino acids needed to build proteins.

The loss made sense: “It saves expending energy on making them ourselves when we can get them from the world around us,” says biochemist Benjamin Pickard of the University of Strathclyde in Scotland. But it has also made animals vulnerable to nutrient deficits. Today, scientists are learning how animals have reconfigured their bodies to detect amino acid deficiencies and react to times of scarcity, and the strategies they’ve evolved to ensure they get enough of the right mix.

In all kinds of ways, Pickard says, as ancient animals diversified into predators and herbivores, “we had to adapt our bodies and life strategies … to supply this permanent hunger for essential amino acids.”

The burst in animal diversity that occurred during the Cambrian period 530 million years ago brought some complications: Early during evolution, animals lost the ability to synthesize nine of the 20 amino acids their bodies require, so they must source them from other life forms. They evolved an array of feeding strategies to satisfy that need.

CREDIT: CHRISTIAN JEGOU / SCIENCE SOURCE

The world is our protein

Even when they’re not actively growing, all animals are in constant need of protein. Our bodies are steadily losing proteins or breaking down old and damaged ones. They must be replaced. For that, our cells need amino acids, organic molecules consisting of a nitrogen-containing stub attached to a carbon-studded molecule. Of the 20 different amino acids we need, our cells can synthesize 11 of them; all they require is a carbon source like sugar or fat, and nitrogen, which we can get from virtually any kind of protein we ingest.

Not that we have to manufacture them: The body can also get these “nonessential” amino acids — which include alanine, asparagine and aspartate — from the diet, to save the energy of synthesizing them.

But the “essential” amino acids that the body can’t produce — like tryptophan, methionine, lysine and leucine — we can get only from our diet. Then there are also several “conditionally essential” amino acids like cysteine and arginine that our bodies normally generate in sufficient amounts, except when demand skyrockets during periods of growth, injury or sickness. In such cases, we need a top-up from our diet. In a 2024 paper, Pickard found that the proteins like keratin that make up human nails and hair contain a lot of these conditionally essential amino acids, which could help to explain why hair and nails tend to grow more slowly or look less healthy when we’re ill: We need to use the amino acids for making more critical proteins.

Nine of the amino acids used to build proteins cannot be made by animals; these are termed “essential” amino acids and must be obtained from the diet. Animals can synthesize the remaining, “nonessential,” ones. But some of these — termed “conditionally essential” — must be obtained from the diet during periods of growth, injury or sickness.

Meat provides animals a balanced amino acid profile with all 20 amino acids, but it can be harder to get this from plants. For one thing, specific plant tissues like leaves contain relatively little protein overall. And although soybeans, amaranth, quinoa, potatoes and pistachios are “complete proteins” — they contain sufficient concentrations of all nine essential amino acids — other seeds aren’t.

Almonds and peanuts are low in lysine and methionine; peas and beans lack methionine and tryptophan; rice, wheat and corn are all low in lysine and isoleucine. Chemical ecologist Georg Jander of the Boyce Thompson Institute, a life science research center in New York, speculates that this could be a strategy evolved by plants to deter animals from eating them. “It’s probably less likely that animals will eat your seeds if they’re not nutritionally good for these animals,” he says.

This nutritional inadequacy presents a challenge for herbivorous animals, says animal ecologist Seth Newsome of the University of New Mexico. “It’s really easy to make a wolf, because wolves eat basically what their body looks like. Their diet mirrors their body,” he says. “But it’s really, really hard to make a moose, because a moose’s diet does not.” Herbivores often avoid deficiencies through bacteria in their gut microbiome that digest the cellulose walls of plant cells, releasing extra protein, and synthesize essential amino acids that their host can then use. Many people consume a diversity of protein-rich plant parts that complement each other’s missing amino acids, for instance by pairing beans and rice.

But essential amino acid deficiencies exist in malnourished populations who rely heavily on staple crops like corn; one 2022 diet survey of people in Malawi estimated that 33 percent of households weren’t eating enough lysine. Such deficiencies can have particularly devastating effects in growing children. In developed countries, protein deficiencies are extremely rare, although people on entirely plant-based diets need to take care to get a balanced mix of amino acids; one 2025 study of nearly 200 vegans in New Zealand estimated that about half of participants might not be getting enough lysine and leucine.

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SOURCE: REPORTING BY K. ZIMMER. CREDIT: KNOWABLE MAGAZINE

SOURCE: REPORTING BY K. ZIMMER. CREDIT: KNOWABLE MAGAZINE

When deficiency strikes

Animals have evolved ways of sensing both the overall amount of protein in their meals and the quality. Lab rats, for instance, can tell if the essential amino acid isoleucine is entirely missing from their meal, making them reluctant to eat it. Lysine-deprived rats prefer to drink lysine-containing solutions over other liquids they’re offered. “The capacity to detect nutrients is one of the most fundamental things an organism has to do,” says molecular biologist David Sabatini of the Institute of Organic Chemistry and Biochemistry, based in Boston and Prague in the Czech Republic. “If you don’t detect the absence of nutrients, you basically are like a runaway train that is consuming without bringing things in.”

But how, exactly, is it done? Part of the answer lies in the brain, says neuroscientist Clémence Blouet of the University of Cambridge in the United Kingdom. Scientists have worked out that the brain tracks the quantity and quality of ingested protein, both by reading signals from the gut and by sensing nutrients in the blood. If all is well, it creates feelings of fullness. Curiously, no amino acid has a stronger effect on satiety than leucine: Blouet suspects that it’s because leucine is a good indicator for the quality of a meal — if leucine is present, odds are good that other essential amino acids are, too.

To work out the mechanism, Blouet and her colleagues examined a group of nerve cells in the brains of mice that are known to regulate satiety. They identified a particular protein in the membranes of these cells, called Cav3.1. When leucine binds to Cav3.1, the neurons become more sensitive to a satiety-boosting hormone called GLP-1. This is how leucine, once enough of it is absorbed through our guts into the blood, tells the brain to suppress appetite.

But the brain isn’t the only organ keeping track of amino acids. Many cells — in the gut, muscles and skin — in the bodies of fruit flies, mice and humans have sophisticated machinery to detect deficiencies and adapt accordingly. Specialized proteins sense the cells’ concentrations of essential amino acids like leucine and methionine as well as conditionally essential ones like arginine. Upon detecting a deficiency, they relay signals to a nutrient-sensing hub of proteins, which then prompts a powerful protein called mTORC1 to order a slowdown in protein-making inside the cell, scientists have learned.

And should the cell’s protein factories — the ribosomes — be in the middle of producing a protein but a particular amino acid is missing, they stop in their tracks, leaving behind a half-baked protein that promptly gets degraded by the cell. This, research shows, activates another protein, GCN2, that triggers a slowdown of protein synthesis.

Importantly, these systems also instruct cells to speed up the destruction of old or unnecessary proteins to make amino acids available for making more necessary ones. “Basically, we start eating our own cells,” says biochemist Stefan Bröer of Australian National University, who authored an article on amino acid absorption in the 2023 Annual Review of Nutrition.

Studies hint that creatures also actively reallocate their amino acid resources in times of scarcity. In experiments, stem cell biologist Elaine Fuchs of the Rockefeller University and her colleagues placed mice on diets that lacked serine — an amino acid that cells can synthesize but that also is needed from the diet by stem cells in the skin, to build the keratin protein of hair and outer skin layers. When animals were deprived of serine, skin stem cells devoted less effort to making hair and instead preserved their resources. This makes sense, Fuchs says: Under stressful conditions, when animals aren’t getting enough dietary protein, “what you want is to be able to repair your wounds. You don’t really care so much about making hair.”

This kind of reallocation of resources, other scientists have found, happens on a body-wide level too. When faced with shortages in essential amino acids, or calorie deficits so extreme that the body has a hard time making nonessential ones, liver and muscle tissue is broken down to release amino acids in a bid to preserve a healthy brain. “You don’t destroy your learning, your memory, your behavior, because the assumption is things will get better,” Sabatini says.

But bodies can’t keep this up indefinitely: Decades-old experiments show that mice on diets lacking in certain essential amino acids eventually die from the deficiency. “This is how we know that these amino acids are really essential,” Bröer says.

An herbivore’s dilemma

Some herbivorous animals have evolved smart strategies to prevent such calamities. That’s especially important for sap-feeding insects like aphids, psyllids and white flies — since sap is scarce in amino acids, especially essential ones. So how do the insects get essential amino acids?

Research has revealed that many of them have cultivated symbiotic relationships with bacteria that reside in specialized cells in their abdomens. These bacteria generate most of the essential amino acids and supply them to their hosts. Few aphids live without Buchnera, and no psyllid has been found without Carsonella; mother insects pass them on to their young when the bacteria enter egg cells.

And many sap-feeders don’t stop there. All 36 Hawaiian species of Pariaconus psyllids host the Carsonella bacterium, but many also get essential amino acids that Carsonella doesn’t produce from Makana and Malihini. The precise makeup of these bacterial communities evolved as their insect hosts adopted different diets and thus had different needs, explains entomologist and evolutionary biologist Allison Hansen of the University of California, Riverside.

In a 2024 study, for example, Hansen and her colleagues learned that, when Pariaconus psyllids left the island of Kauai a few million years ago to colonize other Hawaiian islands, some species lost their Malihini bacteria and others lost both Malihini and Makana. These insects had evolved a new habit of stimulating plants to produce thick leaf and stem growths, called galls, to live in and feed on. These galls are rich in amino acids that the psyllids can eat — so, says Hansen, “they started to lose their co-symbionts as they evolved as a gall feeder.”

Insects like psyllids can survive on their protein-poor diets of plant sap because they carry symbiotic bacteria in their bodies that supply essential amino acids. Many psyllids of the Pariaconus genus carry several such bacteria, and these communities have evolved as the insects adapted to different diets. For instance, species like P. dorsotriatus stimulate plants to produce structures called galls (top panel) that enclose the developing insects — and these species have lost some of their symbionts. That’s probably because the galls are nutrient-rich and adequately supply the young insects (bottom panel) with amino acids.

CREDIT: D.M. PERCY

Other herbivores lean on gut-dwelling bacteria to supply amino acids. That includes tree-dwelling turtle ants, which get some nonessential and essential amino acids in this manner, as molecular ecologist Jacob Russell of Drexel University in Pennsylvania and colleagues discovered in 2018. Curiously, although the ants’ diet of nectar, pollen, spores and honeydew probably supplies a full range of amino acids — other insects eating the same do just fine — turtle ants get a big health boost from their gut bacteria. The microbes help to supply the amino acids needed to make the insects’ skin-like cuticle, for example.

The ants likely acquire the bacteria from one another during habitual exchanges of fluid from mouths and anuses. One 2023 study suggests that young queens get bacteria this way before leaving their parental colonies to establish their own. “They’re transmitting those microbes to their offspring,” Russell says.

Some mammals, too, receive a top-up of amino acids from gut bacteria they receive from their mothers during birth and while nursing. Ruminants — herbivores like cows, deer and sheep with microbe-rich four-chambered stomachs — are best known for this. Dairy cows get between 25 and 75 percent of their essential amino acids from gut bacteria, and that is why cows being raised as livestock can be fed on a corn-rich diet that contains little lysine. (Pigs and chickens, which lack such complex digestive systems, require supplements of lysine and other essential amino acids.)

New Mexico’s Newsome suspects that gut bacteria might be helpful protein sources of essential amino acids for many mammals — “I think it’s a process that’s fairly ubiquitous,” he says. Detailed analyses of the blood of herbivorous kangaroo rats of the New Mexico desert, for instance, suggest that more than a third of the essential amino acids in their bodies may originate from gut microbes. And in 2023, a group of scientists in China and the United States identified gut bacteria in giant pandas that seem to modestly boost the amount of essential amino acids in their hosts’ intestines. Perhaps these bacteria help make up for some of the nutritional shortcomings of bamboo, which contains low levels of tryptophan and histidine.

There’s also some evidence that humans may get some essential amino acids from gut microbes, but Bröer says more research is needed to establish how large of a contribution these make to human health. (In any case, he says, the nutrients are still essential; it’s important that vegans and vegetarians get a full range of amino acids from their diet.)

Little by little, science is revealing how animals have managed to survive and thrive, even if they eat only plants, after our ancestors made a risky move to give up the ability to synthesize all amino acids. “Clearly, given that we’re all still here 530 million years later,” Pickard says, “that was a successful strategy.”

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Katarina Zimmer is a science and environment journalist based in Germany. She is a special contributor to Knowable Magazine, where she covers the energy transition and planetary health. Her other work is published in National Geographic, Scientific American, BBC Future and elsewhere. Check out more of her work at www.katarinazimmer.com.

FOOD & ENVIRONMENT | VIEW ON WEBSITE

Can tinkering with plant pores protect crops against drought?

It’s not an open-and-shut case. But researchers are finding out plenty by genetically altering the numbers of these openings, as well as simulating future atmospheres, and more.

By Tim Vernimmen    12.01.2025

Lea en español

Though we cannot hear it, plants are constantly emitting and absorbing gases through millions of little mouths on the surface of their leaves and stems.

Just by opening and closing, these pores (“stomata” in Greek and botanist-speak) fulfill crucial functions in the plant — allowing the entry of carbon dioxide (CO_2) for the solar-powered process of photosynthesis, through which plants produce their own food (as well as the oxygen we breathe).

Whenever they’re open, stomata also allow water vapor to escape, cooling down sun-exposed leaves and creating the physical traction that pulls water up through the plant from the roots.

But in a warmer world with more frequent droughts, stomata can also be liability, presenting plants with a balancing act: Keep stomata open and make sugars, or close them to save water. Which is why an increasing number of researchers are keen to study stomata and figure out ways to manipulate them and develop hardier crops.

“Water is the No. 1 limitation to crop production globally,” said plant physiologist Andrew Leakey of the University of Illinois Urbana-Champaign at a 2025 meeting of the Society for Experimental Biology that featured a surprising number of talks on stomata. “It’s a very relevant issue today that will only become more significant as climate change progresses.”

In a typical stomate structure, two bean-shaped or dumbbell-shaped guard cells surround a pore. Depending on environmental conditions such as the amount of water in the plant, the guard cells shrink to close the pore, or swell to open it, allowing the movement in and out of water vapor, carbon dioxide and oxygen.

Though photosynthesis requires those pores to open, there’s a great amount of variability in how much water is lost in the process. One of the most efficient crops is sorghum, a drought-adapted cereal that originated in Africa and is popular across the tropics and subtropics. A 2024 study found that in many sorghum plants, stomata move fast — opening just long enough to let in the CO_2 needed for photosynthesis and closing right after. “I’d never seen such a tight relationship in any of the species I’ve studied,” said study coauthor Tracy Lawson, now also at Illinois Urbana-Champaign. She hopes that disentangling the mechanism behind this precise coordination might inspire efforts to improve thirstier crops.

Some scientists had been initially optimistic that higher CO_2 levels in the air — amounts have increased from 280 parts per million to 422 parts per million since the Industrial Revolution — might mean that plants would lose less water, because they don’t have to open their stomata as much to get enough CO_2. Starting in 2004, Leakey and colleagues set out to test this. They surrounded plots in a soybean field with a network of computer-controlled pipes puffing out extra CO_2, effectively mimicking an atmosphere with 550 to 585 parts per million of the gas.

After eight years of growing soy under these conditions — sometimes using retractable awnings to create artificial droughts — the researchers found that soy plants did, indeed, keep their stomata open for less time in response to higher CO_2. They also increased water efficiency and rates of photosynthesis. In the wettest years, this led to a 20 to 25 percent increase in soybean yield.

But there was a catch: When the plants were exposed to drought conditions, “the benefits of high CO_2 can diminish to nothing,” Leakey said. That’s because at high CO_2 levels, the plants grew much bigger early in the season — and then required more water later. This suggests that we cannot count on rising CO_2 to improve water efficiency, since droughts are becoming more frequent.

View from the top of a shelter with a retractable, transparent roof that is used by Andrew Leakey and colleagues at the University of Illinois Urbana-Champaign in their studies. The shelter automatically closes when it rains and is combined with drip irrigation. Researchers use it to study how crops respond to variations in water supply as well as different levels of carbon dioxide.

CREDIT: ANDREW LEAKEY

A deceptively simple way of helping plants preserve water might be to reduce the number of stomata in plant leaves. This has been achieved in various crops by boosting the activity of a gene called EPF1  that regulates how many stomata develop. The resulting stronger genetic signal leads to crops with fewer stomata — and improved water-use efficiency.

Leakey’s lab, for its part, reported last year that modifying an EPF  gene reduced the number of stomata in sorghum by about 30 to 60 percent. That was enough to lower water loss by 30 to 34 percent without limiting the plants’ rate of photosynthesis or growth.

In sugarcane, however, the team found they couldn’t reduce the number of stomata as drastically. Like in sorghum, the remaining stomata opened wider — and in sugarcane’s case, since there were still enough stomata around, the extra dilation eliminated any water savings. In a follow-up analysis of published research across 10 different plant species, including wheat and corn, Leakey and colleagues observed this to be a widespread phenomenon. While reducing the number of stomata almost always saved some water, the savings were less than expected.

Tinkering with the EPF  genes can have undesired effects, too. The sorghum plants that were modified to have fewer stomata, for example, also had much smaller, underdeveloped flowers and produced significantly fewer seeds, presumably because the genes are involved in these processes too. Leakey and his team are now working to make more precise modifications that affect the genes’ activity only during early leaf development.

These images from an experiment by Andrew Leakey and colleagues show how a sorghum plant engineered to have fewer stomata (right) is more resistant to drought than an unmodified one (left). Red circles in the bottom images indicate the stomata in a leaf sample from each plant.

CREDIT: JOHN FERGUSON AND ANDREW LEAKEY

The team is also increasingly using artificial intelligence to speed up the discovery of promising genes to modify, and to evaluate new, genetically changed crop variants in the lab and field.

This can make a big difference. For an experiment on sorghum published in 2021, Leakey’s team grew 869 genetic variants of the crop in field trials across two years. “There were 4,000 leaf samples with almost 3 million stomata on them, which we counted,” he recalled. In the past, such counting was done manually, by painting nail varnish on leaves, peeling it off and counting the marks left by stomata under the microscope. “People in my lab don’t particularly enjoy doing that thousands of times,” he said.

Instead, his team uses a method called optical tomography in which “you just take a piece of frozen leaf, use double-sided sticky tape to attach it to a microscope slide, and then in about a minute, you can scan the surface.” A machine-learning tool then counts the stomata.

This device is used by researchers to simultaneously measure photosynthesis and gas exchange in plant leaves, helping them to understand what the leaf’s stomata are up to.

CREDIT: COURTESY OF LI-COR MARKETING

In other progress, Leakey’s team has developed a system that allows them to watch stomata under the microscope while measuring the gases passing through them. And researchers are working on ways to use drones to monitor the growth and leaf temperatures of plants in fields at a previously unimaginable scale. This makes it possible to far more quickly evaluate new genetic variants in many different environments and under a variety of conditions.

This knowledge can then be used in models that allow researchers and potentially breeders to predict how tinkering with genes will affect the opening and closing of stomata, says ecophysiologist François Tardieu of the French National Research Institute for Agriculture, who specializes in maize. He has shown that more stomatal opening predicts better yield in favorable conditions — but, significantly, less yield in stressful conditions such as heat or drought.

This may have important implications, Tardieu said. Breeding companies tend to focus on measuring yield — and though this has so far been very effective, yield-based selection may be too slow and reactive to keep up with increasing hot and dry spells. “If we want to prepare for climate change, perhaps we’ll have to change our ways,” he said.

In addition to conducting experiments at much larger scales, that might mean zooming in on what plants are doing when we haven’t been paying attention — at night, for example. That is when plant physiologist Lorna McAusland of the University of Nottingham, England, can often be found roaming around her test fields. “Our nights are warming up at about 1.4 times the rate of daytime temperatures,” she said, “because of increasing cloud cover. And for crops, warmer nights may mean lower yields.” In rice, for example, scientists have found that with every 1 degree Celsius increase at night, yields declined by 10 percent. Such trends have been documented for crops like wheat, too.

To study the reaction of stomata to these trends, McAusland and her team heated their fields using infrared light. (This was not without risk: “I actually burned my hair in the field,” she recalled.) They then measured the gases passing through pores at night in 12 wheat varieties. Those that open their stomata more at night tended to maintain their yields compared with varieties that close them, the scientists found.

McAusland’s research underscores the importance of breeders knowing what stomata are up to in the crops that they select — at night as well as in the daytime. Plants don’t just use opened stomata at night to cool down; she has evidence they use them to absorb condensed water from their own leaves, which may be increasingly important in the face of worsening droughts. “Before this trait gets bred out,” she said, “we really need to work out why they do it.”

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Tim Vernimmen is a freelance science journalist based near Antwerp, Belgium. This is the first Knowable story he reported from his hometown.

HEALTH & DISEASE | VIEW ON WEBSITE

Achieving lasting remission for HIV

People infected with HIV must take antiretroviral drugs for life. But promising trials using engineered antibodies suggest that ‘functional cures’ may be in reach.

By Andrea Teagle    11.19.2025

Lea en español

Around the world, some 40 million people are living with HIV. And though progress in treatment means the infection isn’t the death sentence it once was, researchers have never been able to bring about a cure. Instead, HIV-positive people must take a cocktail of antiretroviral drugs for the rest of their lives.

But in 2025, researchers reported a breakthrough that suggests that a “functional” cure for HIV — a way to keep HIV under control long-term without constant treatment — may indeed be possible. In two independent trials using infusions of engineered antibodies, some participants remained healthy without taking antiretrovirals, long after the interventions ended.

In one of the trials — the FRESH trial, led by virologist Thumbi Ndung’u of the University of KwaZulu-Natal and the Africa Health Research Institute in South Africa — four of 20 participants maintained undetectable levels of HIV for a median of 1.5 years without taking antiretrovirals. In the other, the RIO trial set in the United Kingdom and Denmark and led by Sarah Fidler, a clinical doctor and HIV research expert at Imperial College London, six of 34 HIV-positive participants have maintained viral control for at least two years.

These landmark proof-of-concept trials show that the immune system can be harnessed to fight HIV. Researchers are now looking to conduct larger, more representative trials to see whether antibodies can be optimized to work for more people.

“I do think that this kind of treatment has the opportunity to really shift the dial,” Fidler says, “because they are long-acting drugs” — with effects that can persist even after they’re no longer in the body. “So far, we haven’t seen anything that works like that.”

People with HIV can live long, healthy lives if they take antiretrovirals. But their lifespans are still generally shorter than those of people without the virus. And for many, daily pills or even the newer, bimonthly injections present significant financial, practical and social challenges, including stigma. “Probably for the last about 15 or 20 years, there’s been this real push to go, ‘How can we do better?’” says Fidler.

An HIV particle budding from an infected T cell. A single HIV-infected T cell can release thousands of new virus particles before dying, although not all of them will be capable of infecting other cells.

CREDIT: NIAID / NIH

The dream, she says, is “what people call curing HIV, or a remission in HIV.” But that has presented a huge challenge because HIV is a master of disguise. The virus evolves so quickly after infection that the body can’t produce new antibodies quickly enough to recognize and neutralize it.

And some HIV hides out in cells in an inactive state, invisible to the immune system. These evasion tactics have outwitted a long succession of cure attempts. Aside from a handful of exceptional stem-cell transplants, interventions have consistently fallen short of a complete cure — one that fully clears HIV from the body.

A functional cure would be the next best thing. And that’s where a rare phenomenon offers hope: Some individuals with long-term HIV do eventually produce antibodies that can neutralize the virus, though too late to fully shake it. These potent antibodies target critical, rarely changing parts of HIV proteins in the outer viral membrane; these proteins are used by the virus to infect cells. The antibodies, able to recognize a broad range of virus strains, are termed broadly neutralizing.

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SOURCE: REPORTING BY A. TEAGLE. CREDIT: KNOWABLE MAGAZINE

SOURCE: REPORTING BY A. TEAGLE. CREDIT: KNOWABLE MAGAZINE

Scientists are now racing to find the most potent broadly neutralizing antibodies and engineer them into a functional cure. FRESH and RIO are arguably the most promising attempts yet.

In the FRESH trial, scientists chose two antibodies that, combined, were likely to be effective against HIV strains known as HIV-1 clade C, which is dominant in sub-Saharan Africa. The trial enrolled young women from a high-prevalence community as part of a broader social empowerment program. The program had started the women on HIV treatment within three days of their infection several years earlier.

The RIO trial, meanwhile, chose two well-studied antibodies shown to be broadly effective. Its participants were predominantly white men around age 40 who also had gone on antiretroviral drugs soon after infection. Most had HIV-1 clade B, which is more prevalent in Europe.

By pairing antibodies, the researchers aimed to decrease the likelihood that HIV would develop resistance — a common challenge in antibody treatments — since the virus would need multiple mutations to evade both.

Participants in both trials were given an injection of the antibodies, which were modified to last around six months in the body. Then their treatment with antiviral medications was paused. The hope was that the antibodies would work with the immune system to kill active HIV particles, keeping the virus in check. If the effect didn’t last, HIV levels would rise after the antibodies had been broken down, and the participants would resume antiretroviral treatment.

Excitingly, however, findings in both trials suggested that, in some people, the interventions prompted an ongoing, independent immune response, which researchers likened to the effect of a vaccine.

In the RIO trial, 22 of the 34 people receiving broadly neutralizing antibodies had not experienced a viral rebound by 20 weeks. At this point, they were given another antibody shot. Beyond 96 weeks — long after the antibodies had disappeared — six still had viral levels low enough to remain off antiviral medications.

An additional 34 participants included in the study as controls received only a saline infusion and mostly had to resume treatment in four to six weeks; all but three were back on treatment within 20 weeks.

A similar pattern was observed in FRESH (although, because it was mostly a safety study, this trial did not include control participants). Six of the 20 participants retained viral suppression for 48 weeks after the antibody infusion, and of those, four remained off treatment for more than a year. Two and a half years after the intervention, one remains off antiretroviral medication. Two others also maintained viral control but eventually chose to go back on treatment for personal and logistical reasons.

Prevention drug progress

In addition to the exciting results of FRESH and RIO, 2025 saw the prevention drug lenacapavir endorsed by the World Health Organization. Whereas current prevention drugs must be taken daily or injected every other month, lenacapavir requires just two injections per year. For high-risk populations — including young women in South Africa, sex workers and men who have sex with men — experts anticipate that the drug could be a game changer, preventing new infections and helping high-prevalence countries turn the tide of HIV.

— Andrea Teagle

It’s unknown when the virus might rebound, so the researchers are cautious about calling participants in remission functionally cured. However, the antibodies clearly seem to coax the immune system to fight the virus. Attached to infected cells, they signal to immune cells to come in and kill.

And importantly, researchers believe that this immune response to the antibodies may also stimulate immune cells called CD8+ T cells, which then hunt down HIV-infected cells. This could create an “immune memory” that helps the body control HIV even after the antibodies are gone.

The response resembles the immune control seen in a tiny group (fewer than 1 percent) of individuals with HIV, known as elite controllers. These individuals suppress HIV without the help of antiretrovirals, confining it mostly to small reservoirs. That the trials helped some participants do something similar is exciting, says Joel Blankson, an infectious diseases expert at Johns Hopkins Medicine, who coauthored an article about natural HIV controllers in the 2024 Annual Review of Immunology. “It might teach us how to be able to do this much more effectively, and we might be able to get a higher percentage of people in remission.”

One thing scientists do know is that the likelihood of achieving sustained control is higher if people start antiretroviral treatment soon after infection, when their immune systems are still intact and their viral reservoirs small.

But post-treatment control can occur even in people who started taking antiretrovirals a long time after they were initially infected: a group known as chronically infected patients. “It just happens less often,” Blankson says. “So it’s possible the strategies that are involved in these studies will also apply to patients who are chronically infected.”

A particularly promising finding of the RIO trial was that the antibodies also affected dormant HIV hiding out in some cells. These reservoirs are how the virus rebounds when people stop treatment, and antibodies aren’t thought to touch them. Researchers speculate that the T cells boosted by the antibodies can recognize and kill latently infected cells that display even trace amounts of HIV on their surface.

The FRESH intervention, meanwhile, targeted the stubborn HIV reservoirs more directly through incorporating another drug, called vesatolimod. It’s designed to stimulate immune cells to respond to the HIV threat, and hopefully to “shock” dormant HIV particles out of hiding. Once that happens, the immune system, with the help of the antibodies, can recognize and kill them.

The results of FRESH are exciting, Ndung’u says, “because it might indicate that this regimen worked, to an extent. Because this was a small study, it’s difficult to, obviously, make very hard conclusions.” His team is still investigating the data.

Once he secures funding, Ndung’u aims to run a larger South Africa-based trial including chronically infected individuals. Fidler’s team, meanwhile, is recruiting for a third arm of RIO to try to determine whether pausing antiretroviral treatment for longer before administering the antibodies prompts a stronger immune response.

A related UK-based trial, called AbVax, will add a T-cell-stimulating drug to the mix to see whether it enhances the long-lasting, vaccine-like effect of the antibodies. “It could be that combining different approaches enhances different bits of the immune system, and that’s the way forward,” says Fidler, who is a co-principal investigator on that study.

For now, Fidler and Ndung’u will continue to track the virally suppressed participants — who, for the first time since they received their HIV diagnoses, are living free from the demands of daily treatment.

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Andrea Teagle is a freelance science writer and adventure seeker based in Cape Town, South Africa.

TECHNOLOGY | VIEW ON WEBSITE

Flying with whales: Drones are remaking marine mammal research

From collecting whale snot to capturing surprising behaviors, aerial drones are giving scientists a new view of life at sea

By Gennaro Tomma    11.12.2025

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In 2010, the Deepwater Horizon oil rig exploded in the Gulf of Mexico, causing one of the largest marine oil spills ever. In the aftermath of the disaster, whale scientist Iain Kerr traveled to the area to study how the spill had affected sperm whales, aiming specialized darts at the animals to collect pencil eraser-sized tissue samples.

It wasn’t going well. Each time his boat approached a whale surfacing for air, the animal vanished beneath the waves before he could reach it. “I felt like I was playing Whac-A-Mole,” he says.

As darkness fell, a whale dove in front of Kerr and covered him in whale snot. That unpleasant experience gave Kerr, who works at the conservation group Ocean Alliance, an idea: What if he could collect that same snot by somehow flying over the whale? Researchers can glean much information from whale snot, including the animal’s DNA sequence, its sex, whether it is pregnant, and the makeup of its microbiome.

After many experiments, Kerr’s idea turned into what is today known as the SnotBot: a drone fitted with six petri dishes that collect a whale’s snot by flying over the animal as it surfaces and exhales through its blowhole. Today, drones like this are deployed to gather snot all over the world, and not just from sperm whales: They’re also collecting this scientifically valuable mucus from other species, such as blue whales and dolphins. “I would say drones have changed my life,” says Kerr.

As a whale exhales snot from its blowhole, a drone collects it, providing scientists with vital information on the animal’s physical state.

CREDIT: OCEAN ALLIANCE

S’not just mucus

Gathering snot is one of many ways that drones are being used to study whales. In the past 10 to 15 years, drone technology has made great strides, becoming affordable and easy to use. This has been a boon for researchers. Scientists “are finding applications for drones in virtually every aspect of marine mammal research,” says Joshua Stewart, an ecologist at the Marine Mammal Institute at Oregon State University.

Crucially, drones reduce the need to get close to whales with a boat. This means less disturbance for the animals, and is also safer for scientists, since being on a small boat close to a giant whale can be dangerous. Drones also have significant advantages over aircraft, which have historically played a large role in collecting whale data. Using an aircraft is expensive and requires a whole crew of people to operate it, while drones are cheaper, easier to use, and need just one or two operators, says Stewart.

Drones allow scientists to “see things from an absolutely new perspective,” says David Johnston, a marine conservation ecologist at the Nicholas School of the Environment at Duke University. The oblique angle from which scientists can view a whale from a ship “doesn't actually give you very much to work with,” says Johnston. The new world of information supplied by drones hovering above is allowing researchers to more easily measure whale size, body condition and health, to identify individual animals from features on their bodies, and more.

Although much drone research happens without close contact with whales, some scientists are using drones to drop movement- and behavior-tracking tags onto the animals. Without drones, researchers must approach whales from a boat, usually using a long pole or an air rifle to attach the tags to the whales. A drone, meanwhile, can simply fly overhead and release a tag attached to a suction cup that “just pops it right on the whale,” says Stewart. Or, as in a study published in August 2025, drones can apply a tag directly on the whale by pushing the suction cup onto its back.

The aerial perspective that drones can provide is revealing novel behaviors. “I have seen more unique behaviors in the last five to eight years with drones than I saw in the 30 years previous,” says Kerr. In 2025, for example, scientists reported that some whales regularly use pieces of kelp to groom each other by rolling lengths of it against podmates’ bodies — an observation gleaned from 9 hours of drone footage of 25 killer whales, filmed off the coast of Washington state.

This unusual example of tool use among cetaceans would otherwise have been almost impossible to capture. “We would never have seen this behavior without the bird’s eye view that the drone gives us,” says study author Michael Weiss, a behavioral ecologist at the Center for Whale Research in Friday Harbor, Washington.

A drone drops a tag that can track movement and behavior onto a blue whale, where it attaches via a suction cup.

CREDIT: OCEAN ALLIANCE

While drones are opening a world of possibilities to whale scientists, there’s still room for improvement. Many drones, especially small ones, have battery limitations. “You can only fly for maybe 45 minutes or an hour with a small drone, if you're really lucky,” says Johnston. Drone regulations limit flight range in many countries — in the United States, for example, operators must keep the machines within their line of sight unless they have a special license.

Kerr and other scientists are testing more ways to use drones, including freeing whales that have become entangled in fishing nets. His team is developing a 3D-printed metal cutting hook that drones can drop onto the nets. As the whale moves, the device slices through the tangle.

The rapid advancement of drone technology makes it difficult to predict what marine mammal research will look like in the future, says Stewart. “It’s hard to imagine what the next thing might be.”

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Gennaro Tomma is a freelance journalist who covers science, including stories on the natural world, biodiversity, conservation, climate change, environmental and science-related policies, and more. His work has appeared in the New York Times, Scientific American, National Geographic, Science, New Scientist and other outlets. Find more on his website: https://gennarotomma.it.

SOCIETY | VIEW ON WEBSITE

What happens to the weavers? Lessons for AI from the Industrial Revolution

Handled right, AI has potential to bring back middle-skill jobs lost to the rise of computers, economists argue. Or, like the mechanized mills of the past, it could toss whole sectors out of work.

By Andrew Singer    11.05.2025

Lea en español

In the blink of an eye, artificial intelligence has been set to work transforming every walk of life — from self-driving taxis, to software that reads X-rays as accurately as radiologists, to virtual assistants that can schedule meetings and draft emails, to original if derivative music created in an instant in the style of Mozart or Marley. Like disruptive technologies before it — think automobiles, mechanical textile looms and more — it promises to radically change the world we live in, including the world of work.

Fascinated and alarmed, economists and policymakers are debating how AI — and especially much anticipated artificial general intelligence, or AGI — will reshape the workforce. Techno optimists argue that technology has historically been a powerful driver of economic growth, spurring new industries with novel jobs. That’s what happened with the advent of the automobile, after all: The ranks of carriage makers, horse breeders and stable owners melted away as jobs opened up in the emerging oil industry, and then in brand new sectors like motor hotels — motels — and drive-in theaters. Why couldn’t the same happen with AI?

But others hold that the changes wrought by AI are of a different scale. International Monetary Fund economists have estimated that AI may affect as many as 40 percent of all jobs as AI-driven machines replace work that was traditionally performed by people, much of it skilled. And even where jobs aren’t lost, work by human beings could become less valuable, causing wages to fall, says Anton Korinek, an expert on the economics of AI at the University of Virginia.

With such worries widely felt, it is perhaps no coincidence that two of the three recipients of the 2024 Nobel Prize for economic sciences have written extensively about artificial intelligence and its potential impact on jobs. MIT’s Daron Acemoglu and Simon Johnson argue that we must act deliberately to ensure that AI’s benefits are shared widely — through government intervention, bold new policies and reskilling programs to avoid deepening inequality and societal unrest in this age of growing automation.

The two economists advise that, as we navigate this moment, we heed lessons from the past — specifically, the early Industrial Revolution, another time of economic and social upheaval, and the flexible thinking of a key figure of that time: Englishman David Ricardo.

Acemoglu, Johnson and their colleagues say that if, like Ricardo, policymakers act with care and flexibility, AI might even help restore what the start of the tech boom put in jeopardy: decent-paying middle-class jobs.

Changes hit home

Ricardo, born in 1772, was a parliamentarian and noted economist of his time. In his younger years, he was a techno optimist of sorts. He believed that new spinning machines that converted raw cotton into yarn were going to increase worker productivity and prove to be beneficial for everyone — workers, entrepreneurs and the public.

The new machinery might initially displace some home-based spinners, he recognized, but eventually those people would find work elsewhere.

English parliamentarian and economist David Ricardo did not foresee the drastic effects of industrialization on workers’ livelihoods. “The same cause which may increase the net revenue of the country, may at the same time render the population redundant, and deteriorate the condition of the labourer,” he later wrote.

CREDIT: WIKIMEDIA COMMONS / PUBLIC DOMAIN

And that’s what happened — at first. Cotton textile manufacturing boomed during Ricardo's lifetime: The new spinning machines developed in the 1770s made producing yarn faster and cheaper. Workers who had spun yarn at home on spinning wheels were disrupted by these new machines, but many were able to transition into another growing cottage industry — weaving the now more abundant and cheaper yarn into cloth.

The first edition of Ricardo’s Principles of Political Economy and Taxation, published in 1817, makes no mention of the potential ill effects of machinery on workers. Indeed, in an 1819 speech before the English House of Commons, he declared that “machinery did not lessen the demand for labour.”

But a different reality was emerging with a second invention: power looms, introduced roughly a generation after the spinning machines. A single power loom could produce more cotton than 10 to 20 handweavers working from home, and the machines were so large that they had to be housed in factory buildings, taking cottage industry weaving off the table. As factory weaving eclipsed home weaving, this time the displaced workers had no place to go, because power looms created relatively few new jobs in the factories.

For home-based weavers, this was a disaster. Family earnings for handloom weavers in two Lancashire towns fell by half over a five-year period starting in 1814, Acemoglu and Johnson recount in a 2024 article in the Annual Review of Economics. Handloom workers in the English cotton industry overall averaged 240 pence per week in 1806, but by 1820 — around the time Ricardo was making his speech in the House of Commons — they were making less than 100 pence weekly.

Handloom weaver wages plummeted after the advent of power looms. Wages for factory workers were not high and did not see growth in the early 1800s. (Numbers shown are nominal wages, not adjusted for inflation or changes in the cost of living.)

Even the factory workers who had jobs tending the powerful new textile looms weren’t faring well. They experienced little real wage growth between 1806 and 1835. Growing wealth inequalities spawned social unrest, especially in the hard-hit industrial north. A major demonstration, with an estimated 60,000 people clamoring for political reform, was broken up by deadly force in Manchester in August 1819, in what is known as the Peterloo Massacre.

Ricardo, who had witnessed firsthand the consequences of power looms in the cotton industry, radically changed his mind. A more nuanced view of mechanization found its way into the third edition of Principles, published in 1821. He inserted a whole new chapter to discuss machinery’s impact, writing, in what amounted to a recantation: “The same cause which may increase the net revenue of the country, may at the same time render the population redundant, and deteriorate the condition of the labourer.”

“Middle skill” fortunes fall

Ricardo’s pivot holds important lessons for today’s labor economists and policymakers as they wrestle with the impact of AI’s impact on jobs and wages, Acemoglu and Johnson say.

But this is not a problem that began with artificial intelligence. Rather, it has been brewing since the 1980s with the proliferation of digital technologies that were soon to dominate so much of business, commerce and society — computers, the internet, smartphones, e-commerce, social media. Just as with power looms at the start of the Industrial Revolution, these failed to spread profits to ordinary workers. Instead, Johnson says, what they’ve done “is help the most skilled or the most educated.”

Since the 1980s, meanwhile, the wages of “middle skill” people — such as those who didn’t attend four-year colleges — stagnated or fell in real terms. The tech revolution “automated away a broad middle-skill stratum of jobs in administrative support, clerical and blue-collar production occupations,” writes David Autor, a labor economist at MIT, in an article in the magazine Noēma. Like the spinners and weavers of yore, those people saw their livelihoods melt away. The result was a hollowing out of the middle class, Autor writes, forcing many to turn to less-skilled, lower-paying work.

Indeed, while average household income in the United States increased by 95 percent after adjusting for inflation over the past four decades, according to the Peter G. Peterson Foundation, a nonprofit focused on the United States’ fiscal health, those gains varied widely among top earners and lower-income groups. In the highest income group, income rose 165 percent between 1981 and 2021, whereas among the lowest group, it grew only 38 percent: The wealthiest group did more than four times better than the lowest income group.

Earning disparities are increasing in the United States. (Numbers are in 2021 dollars and don’t factor in the effects of taxes or assistance programs.)

CREDIT: PETER G. PETERSON FOUNDATION

How AI can help

And now comes AI. Will it worsen the trend — or, if it’s handled right, might it present an opportunity? Johnson, Autor and Acemoglu express optimism. “AI — used well — can assist with restoring the middle-skill, middle-class heart of the US labor market that has been hollowed out by automation and globalization,” Autor writes. By training individuals in the application of AI software, middle skill workers might be able to take on many decision-making tasks previously assumed by doctors, lawyers, software engineers and even college professors. An experienced medical worker, for example, could master a new medical device, like the use of a new type of catheter, or could carry out an unfamiliar procedure during a medical emergency.

In the health care sector, “there are so many expert decisions to make, so much technology in use, and so many rigorously trained care providers who are not MDs but who could likely perform at a higher level — that is, do higher-stake tasks — with better support tools,” Autor says. Lung ultrasound, for example, is a promising technology for diagnosing patients with shortness of breath. Although it’s typically performed and interpreted by medical doctors, in a recent study health care clinicians not experienced in lung ultrasound “were successful in obtaining high-quality lung ultrasound clips using an AI tool,” Autor says.

Elsewhere, Autor adds, the HVAC industry (heating, ventilation and air conditioning) is drawing on AI tools that provide real-time guidance and remote diagnostics to enable HVAC technicians to solve more complex problems. Technicians who are already on-site in a home or building can use a ChatGPT-type AI tool for troubleshooting problems using a flowchart. Earlier, they might have had to reach an expert by phone for help.

A pre-AI analogy to these kinds of changes would be the rise of nurse practitioners, says Johnson. “There weren’t very many nurse practitioners 30 years ago. And now every pediatrician’s office has them. And parents are very grateful for the advice and access that they can get, because they have these highly skilled people who do not have MD degrees, but they are enabled — they have been empowered by their licenses.”

The idea isn’t to replace doctors, Johnson adds. “We’re just saying: Redress that balance. Boost the people who don’t have four years of college. Enable them to be more productive.”

Not all economists think this sort of solution will work with AI, though, especially once AGI, with human-level cognitive abilities, arrives on the scene. “The key distinction from past technological changes is that AGI would be capable of performing any cognitive task, potentially leaving few unique economic roles for human workers,” Korinek says. “This could lead to widespread labor displacement and significant wage declines” — unless governments intervene to avoid further widening of the wealth gap.

Growing economic hardship of workers in England in the early part of the 1800s led to civil unrest. In 1819, up to 18 people were killed and hundreds injured during protests in the northern city of Manchester when cavalry charged into the crowd. The event, which became known as the Peterloo Massacre, led to increased suppression in the short term but ultimately to reforms such as an expanded right to vote.

CREDIT: RICHARD CARLILE / PUBLIC DOMAIN

In the short term, Korinek says, this might mean upskilling workers in roles requiring still uniquely human abilities like “authentic human connection, emotional intelligence and ethical oversight,” where machines don’t excel or don’t satisfy a human need. Examples could include psychotherapists, childcare providers and religious counselors.

Further down the road, societies might need larger shifts, such as sharing prosperity through the implementation of a universal basic income: no-strings-attached regular cash payments from governments that citizens receive whether or not they work.

Guidance from the past

There are few convincing studies at this point on the impact that AI, including AGI, will have on global jobs and wages. Partly this is because researchers have to take into account jobs that don’t yet exist in industries not yet invented. As we wait for this new world to unfold, however, the life and times of David Ricardo might offer some food for thought.

The new machinery introduced to English textile factories in the early 1800s had a much worse impact on workers’ lives than Ricardo ever anticipated. It took him a long time to realize this. When he did, he was nearly 50 years of age, wealthy, well-connected and at the top of his profession. It would have been easy to ignore the untoward effects from these amazing machines, the power looms. Instead, Ricardo admitted his mistake and modified his theories. That kind of fluid thinking, and intellectual integrity, will be crucial in the age of AI, Johnson says. “We have much to learn from Ricardo’s openness to new ideas and new ways of thinking about economics,” he and Acemoglu write in their paper.

This 1835 image depicts a scene from a weaving mill with women working at power looms. The rise of factory weaving devastated the livelihood of hand weavers.

CREDIT: E. BAINES, HISTORY OF THE COTTON MANUFACTURE IN GREAT BRITAIN / PUBLIC DOMAIN

England did learn from the handloom weavers’ collapse, and the travails of its laboring class generally. It expanded the political voice of its industrial cities. Before 1832, cities like Manchester weren’t even represented in Parliament. England’s Factory Act, passed in 1833, introduced what was arguably one of the world’s first enforceable child-labor factory regulations. (It required factory inspections.) The government repealed its protectionist Corn Laws in the 1840s, which made food more plentiful and cheaper for the urban laboring class. Ricardo, a free trade advocate, was a powerful voice urging the Corn Laws’ repeal.

The new world is hurtling toward us. Daniel Kokotajlo, former governance researcher at ChatGPT developer OpenAI, who now heads the AI Futures Project, has posited a scenario in which AGI is fueling an economic boom by 2027 — but is also causing millions of job losses because its software is outperforming humans in coding, research and other cognitive tasks. (“It might take a few years longer than 2027,” he says now.)

Other predictions differ — they range from a world in which more and more wealth becomes sequestered with the few, to one in which AI helps to reduce inequalities. It depends a lot on how our governments elect to act. “All the smarts, all the talent around computer science is being drawn into the pursuit of AI, to a degree that I haven’t seen since the internet really boomed at the end of the 1990s,” Johnson says.

But, he adds, as a look at the industrial revolution and history more broadly makes clear, “just because you have new miracle machines does not mean most people will benefit.”

10.1146/knowable-110525-1

Andrew Singer is a New York-based freelance journalist who specializes in emerging technologies and their impact on business and society. He is the founder and former editor in chief of Ethikos: The Journal of Practical Business Ethics.

LIVING WORLD | VIEW ON WEBSITE

How a humble weed became a superstar of biology

Arabidopsis thaliana was always an unlikely candidate for the limelight. But 25 years ago, the diminutive thale cress launched the botanical world into the molecular era.

By Rachel Ehrenberg    11.03.2025

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In November of 1956, after weeks of protests and calls for free elections in Hungary, Soviet tanks rolled into Budapest to crush the uprising. Well over a hundred thousand people fled the country seeking asylum. Among them was a young geneticist named George Rédei, who headed for the Austrian border with a small vial of seeds tucked in his pocket.

The seeds belonged to a spindly weed in the mustard family called Arabidopsis thaliana. Today, that weed is widely regarded as a botanical superstar. Arabidopsis has been the focus of some 100,000 research papers. Its seeds have flown around the Moon; it is the go-to plant for experiments on the International Space Station. And when the scientific community decided which plant should be the first to have its genome sequenced, Arabidopsis emerged as the winner. This year marks the 25th anniversary of when the world got its first glimpse at that genome, launching the much-studied plant toward even greater fame and scientific value.

Setting off from his homeland, Rédei could never have predicted all the ways that Arabidopsis would revolutionize understanding of plant biology, from root to shoot. Discoveries made in the little weed laid the groundwork for ways to improve crops and enhance food security, to manage ecosystems and mitigate climate change. The plant even yielded insights into animal evolution and human health. The Arabidopsis genome still serves as the first reference for researchers investigating genetic and development puzzles in other plants.

Several genes characterized in Arabidopsis have enabled a range of key discoveries in economically important plants, including (clockwise from top) potato, tomato, corn, soybean, cotton, rice, sweet orange and sugarcane.

But the plant’s fame was never a given. It took years for Arabidopsis to prove its mettle against money-making crops like corn. Early on, funding was uncertain. It was Rédei and then a small but ambitious community of young scientists who took up the Arabidopsis campaign and brought the little plant into the limelight. The world of plant biology — and all of science — hasn’t been the same since.

Secrets of plants and beyond

After fleeing Hungary as a refugee, Rédei eventually made it to the University of Missouri in Columbia in 1957. On the faculty there, he planted the Arabidopsis seeds he’d brought across the ocean. He was familiar with the work of German botanist Friedrich Laibach, who had realized that the weed could be a powerful biological research tool, a model organism akin to the fruit fly Drosophila melanogaster. Rédei became convinced of the plant’s prowess; he hoped that it could help reveal the genetic secrets of all plants and perhaps other living things.

He was an outlier. At the time, most plant research focused on farm crops or decorative plants — plants with obvious economic value. Scientists usually studied their favorite species to answer specific questions: To figure something out about fruit ripening in tomatoes, you did experiments with tomatoes; to understand flowering time in cotton, you turned to cotton.

Scientists had already made some profound discoveries — with broad implications — by studying plants. Gregor Mendel’s famous work on garden peas in the mid-1800s led him to uncover the basic principles of how traits are inherited (though the implications of his experiments weren’t appreciated until the early 1900s).

Corn too, was an early model for investigating genetics. In one fascinating example in the 1940s, geneticist Barbara McClintock was tracking mutant corn plants with strangely colored kernels. She would ultimately show that these oddballs often resulted when bits of chromosomes were deleted or broken — sometimes genetic material was even transferred from one chromosome to another. The discovery of these “jumping genes” — which were later found in all kinds of species, including people — led, decades later, to her 1983 Nobel prize.

Mutant organisms, like McClintock’s corn plants, were a crucial tool in the early years of genetic research. Identifying how a particular gene affected an organism typically involved looking at what happened to an organism when the gene didn’t work. You began by seeking mutant versions of the organism (say, a fruit fly with white eyes instead of red) or you created mutants — with plants this meant zapping the seeds with X-rays or chemicals. When you grew those seeds, one among thousands of the infant plants might be weird. Maybe it couldn’t bend its stem toward the light, or its leaves lacked green pigment.

You then worked backward from the mutant to try to figure out what gene or genes had been disrupted. But that was far from easy. It often took generations of genetic breeding and years of careful experiments to identify the precise gene involved, let alone understand what that gene did.

And doing those investigations in a plant such as corn carried extra challenges. It required acres of fields, farm machinery and lots of patience. In breeding experiments set up to discover the effects of a gene, or how a trait changes over generations, you had to wait through a months-long growing season for seeds to mature. Then you had to wait until the next spring to plant those seeds. Then you had to wait for those plants to grow their own offspring. Greenhouses and colleagues living in warmer places with longer growing seasons could help, but the timeline was always long.

Rédei thought that Arabidopsis could circumvent those problems, and other challenges besides. Laibach, in Germany, had already detailed many of the qualities that made the plant so amenable to genetic studies — its small size (thousands could be grown in a small room); its short generation time (six weeks); its prolific seeds (more than 10,000 per plant). Laibach’s observations with a microscope had also revealed that Arabidopsis has only five pairs of chromosomes — whereas corn has 10 pairs, and wheat has 21. That would make it much simpler to map a particular gene to a particular spot on a chromosome.

In Missouri, Rédei continued to investigate the little mustard, conducting experiments with Arabidopsis plants grown from seeds he’d procured from Laibach before leaving Hungary. A small community of researchers, mostly in Europe, were also working with the plant, but there was little outside interest — indeed, after initially funding Rédei’s research, the US National Science Foundation withdrew its support in 1969. It reasoned that a plant — a weed, no less — would never generate useful knowledge.

Arabidopsis garnered attention as a promising model organism thanks in part to geneticist George Rédei (top), with scientist (and soon-to-be Nobel laureate) Barbara McClintock in 1978. Scientists such as Maarten Koornneef (bottom left, with lab tech Corrie Hanhart) would investigate thousands of Arabidopsis plants to uncover the genetics behind particular traits. Young investigators, including some gathered for a meeting in 1985, helped to cement the plant’s value as a tool for molecular biology research, ushering in its widespread adoption. This community included (bottom right, from left to right) Shauna and Chris Somerville, Elliot Meyerowitz, David Meinke, Marta Crouch and Koornneef.

CREDITS: NATIONAL LIBRARY OF MEDICINE (TOP); COURTESY OF MAARTEN KOORNNEEF (BOTTOM)

A promising plant for the molecular era

Still, Rédei kept at it and in 1975, in the Annual Review of Genetics, he argued the plant’s case to the broader scientific community.

Not long after, Chris Somerville, fresh off a PhD in E. coli genetics, and his wife, plant pathologist Shauna Somerville, read Rédei’s paper and decided that Arabidopsis was the right organism to usher plant science into the modern, molecular era. Scientists working with the E. coli bacterium had recently developed ways to cut strands of DNA and fuse them back together; by 1978, researchers using those techniques had engineered the bacterium to make human insulin. Scientists like the Somervilles — many of whom had begun their careers studying other long-standing model organisms, such as yeast, bacteria and fruit flies — began eyeing Arabidopsis as a promising tool for probing life’s mysteries at the molecular level.

“It was very attractive for people who were working on other systems and had a bit of a pioneering spirit to try something new,” says biologist Elliot Meyerowitz of Caltech. Meyerowitz had recently finished a PhD focused on Drosophila developmental genetics and had also read Rédei’s review paper. When he started his own lab at Caltech, its main focus was Drosophila development and genetics, but pretty soon it was investigating Arabidopsis too.

Leading scientific model organisms include: The fruit fly Drosophila melanogaster (top left), which has yielded critical insights into genetics, animal development and human behavior; baker’s yeast (Saccharomyces cerevisiae, top right), a crucial tool for understanding cells and cancer; thale cress (Arabidopsis, bottom right), which exposed many secrets of plants and more; and the bacterium E. coli (bottom left), which has helped elucidate fundamentals of biology including the role of mutations in evolution and the nature of DNA.

CREDITS CLOCKWISE FROM TOP LEFT: RYSZARD/FLICKR; MOGANA DAS MURTEY AND PATCHAMUTHU RAMASAMY/WIKIMEDIA COMMONS; WERNER LAUCKNER/iNATURALIST; NIAID/FLICKR

Over in the Netherlands, plant scientist Maarten Koornneef was working on a genetic map of Arabidopsis — a guide to where the plant’s various genes were located on its chromosomes — using data garnered in part from Rédei’s work and Koornneef’s own investigations of all sorts of mutant plants. Such maps could help scientists find a particular gene — say, one that prompted early flowering, larger seeds or resistance to a fungus — clone that gene, and then look for it in other plants.

Meanwhile, at the University of Illinois, the Somervilles were investigating how plants regulate their use of carbon dioxide with Arabidopsis mutants that couldn’t grow in regular air, but could grow in air enriched with carbon dioxide. This research laid the groundwork for ways to make photosynthesis more efficient in various crops and led to some high-profile papers that brought the plant to the attention of still more scientists. When the duo moved to the Department of Energy’s plant research laboratory at Michigan State University in 1982, they began several other Arabidopsis projects — and they attracted new converts.

Among them was Mark Estelle, who had just finished a Drosophila-focused PhD. At first, Estelle tackled oats — an important plant, but one with a large, complex genome. “That didn’t last very long, because that’s a ridiculous genetic system,” he says. A model organism, though, would allow for sophisticated genetic experiments that then could be applied back to plants of economic importance. He made the switch to Arabidopsis and began investigating auxins, a class of potent hormones that coordinate growth and development in plants.

“We could screen a thousand plants in each Petri dish looking for mutants,” says Estelle, who continues to use the little plant to investigate auxins at UC San Diego. “That’s very powerful.”

Meyerowitz’s lab then made a compelling discovery. Experiments led by Leslie Leutwiler, a post-doc in his lab, had found that the Arabidopsis genome was on the small side. Their estimates suggested it had a mere 70,000 kilobases pairs (kbp) of DNA — in contrast with estimates of 1.8 million kbp for soybeans and a whopping 5.9 million kbp for wheat. And those five pairs of Arabidopsis chromosomes didn’t have huge quantities of DNA sequences that were duplicated over and over, like some plants did. This made it much more technically feasible to hunt for genes in a haystack of DNA, as Meyerowitz and his graduate student Robert Pruitt pointed out in in the journal Science in 1985.

And the results kept coming. In 1986, plant molecular geneticist Caren Chang, then a graduate student in Meyerowitz’s lab, cloned and sequenced an Arabidopsis gene for the first time; it carried instructions for making an enzyme that helps plant cells survive when they are starved of oxygen — for example, during times of flooding. “So little was known then,” Chang, now at the University of Maryland, says of those salad days. “It was this big open frontier.”

That same year, another beneficial characteristic of Arabidopsis was added to list: The plant could easily and efficiently take up foreign genes with the help of a DNA-carrying bacterium, a process known as genetic transformation. Scientists had been racing to insert new genes into plants since the late 1970s. It was a team of Monsanto researchers who put all the pieces together in Arabidopsis, showing in a 1986 Science paper that they had put an antibiotic-resistance gene into the plant.

Things were coming to a head. Despite earlier pushback — many crop scientists at the US Department of Agriculture had considered Arabidopsis an annoying upstart and were rumored to refer to it as “the A-word” — the larger scientific community knew that it needed a model plant if the field were to progress.

“One of the reasons why we needed a model, why every field needs a model, is because the development of new techniques, especially molecular biology techniques — it’s complex. It’s expensive, it’s time consuming,” says molecular biologist Marc Somssich, now at the seed company KWS Saat in Germany, who wasn’t involved in those early days but chronicled them in a 2019 paper. “So instead of developing new techniques for a thousand different plants, we develop these techniques for one.” A model plant would mean standardized techniques, shared lab protocols, organism-focused conferences — and everyone benefiting from the greater accumulation of knowledge.

Tomato was under consideration; so was petunia. But Arabidopsis pulled into the lead. Discoveries made with the little mustard kept appearing in high-profile science publications. A critical mass of scientists, including heavyweights like James Watson, codiscoverer of the structure of DNA, and yeast geneticist Gerald Fink took up the Arabidopsis banner.

At the National Science Foundation, new leadership, including plant biologist Mary Clutter, understood the value of bringing the plant community into the modern era. In 1990, the NSF developed a coordinated international strategy of Arabidopsis research goals. This included an ambitious plan to sequence all the DNA letters in its genome.

“Think of Arabidopsis as the Hyundai of plants,” Fink told Mosaic, the NSF’s flagship magazine, in 1991. “If the Hyundai represents ‘car’ at its most fundamental, Arabidopsis is the essence, the stripped-down version, of [a] flowering plant. What we learn from it will most certainly be applicable to any plant of agricultural importance. It will tell us a considerable amount about how all green plants are structured and ultimately, perhaps, how their genomes may be modified to enhance productivity.”

Wild tomatoes have small, berry-sized fruits, but domestication brought about the large, fat, many-sectioned tomatoes known today as beefsteaks. In research informed by discoveries in Arabidopsis, scientists found that these hefty fruits result from an overproduction of stem cells due to mutations in a signaling molecule that usually acts as a brake on stem cell production.

CREDIT: DOMINIK HUNDHAMMER / WIKIMEDIA COMMONS

In December 2000, the Arabidopsis Genome Initiative, which involved scientists from around the world, published the sequence of the Arabidopsis genome in Nature. The genome provided a draft recipe book for plant life. It revealed some 25,000 genes (a later, more accurate count put the number of genes at over 27,000), roughly 30 percent of them with completely unknown functions. It provided fodder for countless hypotheses and experiments that were to come.

A blooming of discoveries

It is impossible to do justice to the discoveries made in the plant since — and to the contributions that each member of the dedicated Arabidopsis research community has made to science.

Since Charles Darwin, for example, scientists had been probing how plants detect blue light, which prompts them to bend toward the Sun. In the 1980s, researchers bred mutant Arabidopsis plants that didn’t respond normally to the blue light signal. Pinpointing the defective gene in the plants soon revealed the first blue-light detector, called a cryptochrome.

Cryptochromes and other light sensors turn out to be critical for how plants integrate an external cue — light — with internal molecular clocks that regulate growth and development, germination time, flowering time and more. And cryptochromes have since been found across the tree of life: in fruit flies, algae, fungi and mice; they are also key in people. Cryptochromes sense the light that sets the body’s circadian rhythms — off-kilter rhythms can contribute to ills such as cancer, heart disease and depression.

Arabidopsis also lent a hand to researchers investigating how flowers and fruits develop their particular shapes and sizes. Among the mutants catalogued in the early days were plants that had one organ replaced by another — they had petals where stamens should grow, for example. Animal versions of these mutants had been investigated in flies (they were tiny monsters with, for example, a leg growing where an antenna should) and research using Arabidopsis revealed the floral version of such body plan genes. This work continues to aid scientists probing the stunning diversity of floral forms, including the abundant petals in “double flower” roses and the lack of sepals in tulips.

Related work on molecules involved in controlling fruit size may one day lead to larger fruits, including kiwis and cucumbers. These regulating genes are also shedding light on how plants we eat today have changed over the eons: In 2015, for example, scientists discovered that a naturally occurring mutation in one of these genes gave rise to the gigantic, fat fruits known as beefsteak tomatoes.

To help students understand plant development and biotechnology, postdoctoral researcher and flower engineer Nick Desnoyer reimagined Arabidopsis using lessons from the plant itself (left). He introduced mutations in a gene involved in the development of different floral organs, leading to additional whorls of petals. Then he crossed that plant with an Arabidopsis that made pink petals, thanks to some genes borrowed from beets. Within two generations he had the showy pink Arabidopsis seen at right.

CREDIT: NICK DESNOYER

Arabidopsis has also shed light on how plants cope with stresses in their environment. A key plant biochemical signaling pathway was discovered in Arabidopsis and later identified in crop plants, including rice and tomatoes. It dealt with responses to an overload of salt, which makes it harder for roots to take in water and hinders growth.

How plants respond to additional foes — bacteria that slip in through plant pores or wounds, insects that stab into a leaf, fungi that slither among plant cells — also came under scrutiny in Arabidopsis, and some of the discoveries had repercussions far beyond the plant world. Unlike mammals, plants don’t have roving immune cells that keep an eye out for pathogens (and keep track of past encounters). Instead, each plant cell must rely on its sturdy cell wall, its own detection machinery, and signals sent plant-wide from the site of the infection or attack.

In 1994 and 1995, scientists reported the discovery of genes that code for a class of plant proteins called NB-LRR receptors, which are critical to the plant immune system. After the Arabidopsis genome was sequenced, investigations of these genes accelerated — Arabidopsis has nearly 150 of them. It turns out that versions of NB-LRR receptors play a role in the inflammatory response of mammals, including people. Variations in some of the NB-LRR genes have been implicated in Crohn’s disease.

Despite the fact that animals and plants went their separate evolutionary ways about 1.6 billion years ago, many human genes known to play a role in disease have related versions in Arabidopsis. That includes some 70 percent of human genes implicated in cancer, a count that is higher than for either yeast or Drosophila. Genes implicated in neurological disorders, including Alzheimer’s and Parkinson’s, also have versions in Arabidopsis.

Despite the huge evolutionary distance, plants have versions of particular proteins and processes that are similar to those found in people, including some that have been implicated in human disease.

The plant also laid a foundation for many biotechnology techniques used in labs today. Methods developed to investigate gene activity in Arabidopsis cells, for example, were adopted for use in zebra fish, Drosophila and even studies of the optic nerve in frogs. The Arabidopsis cryptochromes are harnessed for studies of mammalian cells that employ optogenetics, a method that allows scientists to investigate and control nerves and other cells using pulses of light.

The list goes on and on, with new findings about the plant continuing to roll out. But will it maintain its status as preeminent model of the plant world? Yes and no. For one thing, molecular biology techniques have become faster and cheaper: While sequencing the Arabidopsis genome took a decade and cost nearly $75 million, today a genome can be sequenced in a day for about $600. This makes it much easier to investigate any plant.

Still, it’s unlikely that any single plant will take Arabidopsis’s place. The community that grew around the little weed, with its commitment to sharing resources, data and lab protocols, can’t be underestimated, and it’s still going strong, says molecular biologist Anna Stepanova of North Carolina State University, who is on the board of directors for the Multinational Arabidopsis Steering Committee. “I’m very optimistic about Arabidopsis staying relevant for hundreds of years to come.”

While enthusiasm for Arabidopsis hasn’t changed, the world of science has — change that the mustard helped foment. Scientists no longer labor in discrete and often siloed disciplines, focusing on physiology or on biochemistry or on morphology or genetics, as they did when Rédei was coming up. The molecular revolution shook up everything, connecting these disciplines and fusing genetics with physiology, development, pathology and more. This integration was already happening among researchers studying other models like E. coli and yeast. Arabidopsis brought it about in the plant world.

A great many of “the classical questions that had been raised by earlier botanists are answered in a molecular and mechanistic level by research on Arabidopsis,” says Meyerowitz. “And a lot of new questions were opened up from that research that people may not even have considered before.”

There are still many such questions, says Chris Somerville. And the weed still has a place in answering them.

“It’s a wonderful place for people to learn about the basic process,” he says. “So first you go to Arabidopsis and you say, well, how is Arabidopsis doing this aspect of biology? And then you can translate it now into the other plants — the other plants we care about.”

10.1146/knowable-110325-2

Rachel Ehrenberg is an editor at Knowable Magazine.

TECHNOLOGY | VIEW ON WEBSITE

Computers are getting much better at learning to “see”

The machine-learning programs that underpin image-recognition still have blind spots, but will they for much longer?

By Kaia Glickman    10.30.2025

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Anyone with a computer has been asked to “select every image containing a traffic light” or “type the letters shown below” to prove that they are human. While these log-in hurdles — called reCAPTCHA tests — may prompt some head-scratching (does the corner of that red light count?), they reflect that vision is considered a clear metric for differentiating computers from humans. But computers are catching up.

The quest to create computers that can “see” has made huge progress in recent years. Fifteen years ago, computers could correctly identify what an image contains about 60 percent of the time. Now, it’s common to see success rates near 90 percent. But many computer systems still fail some of the simplest vision tests — thus reCAPTCHA’s continued usefulness.

Newer approaches aim to more closely resemble the human visual system by training computers to see images as they are — made up of actual objects — rather than as just a collection of pixels. These efforts are already yielding success, for example in helping develop robots that can “see” and grab objects.

Better neural networks

Computer vision models employ what are called visual neural networks. These networks use interconnected units called artificial neurons that, akin to in the brain, forge connections with each other as the system learns. Typically, these networks are trained on a set of images with descriptions, and eventually they can correctly guess what is in a new image they haven’t encountered before.

A major leap forward in this technology came in 2012 when, using a powerful version of what’s called a convolutional neural network, a model called AlexNet was able to correctly label images it hadn’t encountered before after teaching itself to recognize images on a training set. It won, by a large margin, the ImageNet Large Scale Visual Recognition Challenge, a contest that’s considered a benchmark for evaluating computer vision tasks. (AlexNet was developed by two students of computer scientist Geoffrey Hinton, the “Godfather of AI” who shared the Nobel Prize in physics in 2024.)

Despite this vastly improved performance, visual neural networks still make puzzling mistakes. In a classic example from 2017, a student-run AI research group at MIT tricked a neural network into labeling a picture of a cat as guacamole. By adding an imperceptible amount of pixel “noise” to the cat image, the model was completely thrown off.

“I was shocked that this was so easy to do — to make the models think the wrong thing,” says computer scientist Andrew Ilyas, a member of that student team who will start a new position in January at Carnegie Mellon University in Pittsburgh.

In a classic example of tripping up an image-recognition program, a team in 2017 introduced some imperceptible noise into an image of a cat. Google’s InceptionV3 image classifier then mislabeled the image as guacamole.

CREDIT: A. ILYAS ET AL / PROCEEDINGS OF THE 35TH INTERNATIONAL CONFERENCE ON MACHINE LEARNING 2018

Moving every pixel in an image just slightly to the left or right can also confuse these visual networks. Researchers did this with images of otters, airplanes and binoculars, and the model could no longer identify the image despite it appearing identical to a person, computer scientists Yair Weiss and Aharon Azulay from Hebrew University of Jerusalem reported in 2019.

This susceptibility to minute changes stems from the compartmentalized way that visual neural networks learn. Instead of identifying a cat based on a true understanding of what a cat looks like, these approaches see a set of features that the network associates with “cat.” These features, however, are not inherent to the notion of “cat,” which Ilyas and his colleagues exploited in their often-cited guacamole example.

“Computers learn lazy shortcuts that are easily tampered with,” Ilyas says.

Today, convolutional neural networks are gradually being replaced by what are called vision transformers (ViTs). Typically trained on millions or even billions of images, ViTs divide images into groups of pixels called patches and cluster regions based on properties such as color and shape. These groupings are identified as physical features, such as a body part or a piece of furniture.

Vision transformers often perform better than previous approaches because they synthesize information from different areas of an image more efficiently, says machine learning researcher Alexey Dosovitskiy, who worked on ViTs at Google.

Blind spots in computer vision programs can be revealed via subtly altered images. The bottom row features four such “adversarial images,” that are still recognizable to human eyes but tripped up the computer.

CREDIT: A. ILYAS ET AL / PROCEEDINGS OF THE 35TH INTERNATIONAL CONFERENCE ON MACHINE LEARNING 2018

Mimicking how the brain sees

Some researchers are now combining elements of various visual neural networks to enable the computers to think more like humans.

Object-centric neural networks aim to do just that. They evaluate images as compositions of objects rather than just grouping similar properties, such as “yellow.” These models’ image-recognition success comes from their ability to recognize an object as separate from its background.

In one recent example, researchers compared object-centric neural networks to other visual neural networks via a series of tests that required the computers to match identical shapes. All the models were trained on regular polygons and performed similarly on these kinds of shapes, but the object-centric models were much better at applying what they learned to irregular, colored and striped shapes.

The top object-centric model correctly matched the abnormal shapes 86.4 percent of the time, while the other visual model was successful only 65.1 percent of the time, as reported earlier in the year by Jeffrey Bowers, a psychologist who focuses on machine learning at the University of Bristol in England, and his colleague Guillermo Puebla, a psychologist at Universidad de Tarapacá in Providencia, Chile.

Object-centric models’ success has expanded beyond two-dimensional images. Newer systems can watch videos and reason about what they saw, correctly answering questions such as “How good are this person’s badminton skills?”

Object-centric algorithms also have been incorporated into robots. Some of these can more accurately grab and rotate objects in three dimensions, completing tasks such as opening drawers and turning faucets. One company is even building flying robots that use these types of visual recognition strategies to harvest apples, peaches and plums. These robots’ precise object detection abilities allow them to determine when fruit looks ripe and deftly swoop in between trees to pick the fruit without damaging its delicate skin.

Scientists expect even more progress in visual neural networks, yet there’s a long way to go before they can compete with the brain’s capabilities.

“There are ways in which the human visual system does strange stuff,” Bowers says, “but never is a cat mistaken as guacamole.”

10.1146/knowable-103025-1

Kaia Glickman is a science journalist from Los Angeles. She’s getting her master’s degree in science communication from UC Santa Cruz, and is thrilled to have seen her first real live banana slug.

Table of Contents

Knowable Magazine: 2026 Feb 8

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