Some researchers who retract their papers do so after others in the scientific community raise red flags to them about their work.Credit: EyeEm/Getty Early last month, evolutionary biologist Nicole King and postdoctoral fellow Jacob Steenwyk retracted their paper in the journal Science1. King was shaken when she realized that the paper — which attempted to use a new data-analysis approach to work out which animal lineages were the first to emerge on Earth — had serious technical errors. But the decision was still clear: “If you know you made a mistake, you’ve got to reverse it,” she says. Retractions caused by honest mistakes are extremely stressful, say researchers Retractions, which have long been associated with misconduct or poor scientific practice, can carry a lot of stigma. As of a decade ago, only about 22% of retractions resulted from authors self-reporting errors2, rather than other scientists raising concerns to journals. Authors whose papers are retracted often stop publishing, especially if the retractions are well publicized3. So King, a researcher at the University of California, Berkeley, was pleasantly surprised to see some scientists celebrating her decision online. “One reason for loving science is how graciously we sometimes deal with errors,” said a bioinformatics researcher on the social-media platform Bluesky. Research has shown that when authors self-retract because of honest mistakes, their earlier work continues to be cited2. These data, along with anecdotes such as King’s story, suggest that attitudes about retractions might eventually shift. Nature reached out to scientists who have openly retracted their studies, and asked about their experiences and lessons learnt. “I completely understand why people are scared about it,” but correcting the scientific literature is important, says Ivan Oransky, co-founder of media organization Retraction Watch, which maintains the world’s most comprehensive database of scientific retractions. Oransky hopes to incentivize researchers with the Ctrl-Z Award — a reference to the ‘undo’ command on a keyboard — launched this week by the Center for Scientific Integrity, Retraction Watch’s parent organization in New York City. Each year, the prize, worth US$2,500, will go to early-career and senior researchers “who discover substantial errors in their published work and take meaningful steps to correct the scientific record”, despite the professional risks. Advancing science Benjamin de Haas, now a neuroscientist at Justus Liebig University Giessen in Germany, navigated a retraction early in his career by reminding himself that mistakes happen, and fixing them is an important part of science. These universities have the most retracted scientific articles Susanne Stoll, then a PhD student at University College London (UCL), was the first to let Haas know that there might be a problem with a paper he had worked on. She joined the laboratory of one of Haas’s co-authors and was examining some of Haas’s old work. The research found that, when people concentrate on a detailed object, the brain’s vision centre blurs out the object’s surroundings — leading to a kind of ‘tunnel vision’4. Stoll suspected that the data analysis was flawed and led to an incorrect conclusion. So, along with her supervisor, she e-mailed Haas. When Haas saw the e-mail, he dug up his old data and, after some frantic analysis, realized that Stoll was right. “That was a real ‘oh shit’ moment,” Haas says. Even so, he didn’t hesitate to contact the journal Current Biology and ask for a retraction. Although he had just launched his own lab and was worried about his career, Haas wanted to be as transparent as possible, to make it clear that there was no misconduct. Now, looking back on that time six years ago, he wishes he could tell himself to remain calm: “You’ll end up with tenure anyway.” Not pointing fingers What helped Haas was the reaction of his former PhD adviser, Geraint Rees, now a vice-provost at UCL. When it became clear that the paper needed to be retracted, Rees offered Haas support, rather than expressing blame or disappointment, Haas says. Working together on the retraction made it less intimidating. The way in which Stoll initially approached him was also essential, Haas says. She was kind and respectful, and they worked together to understand the issue. “We had a common goal,” he adds. King had a similar experience. Almost as soon as her paper came out, she reached out to evolutionary biologist Casey Dunn, a researcher at Yale University in New Haven, Connecticut, to discuss the findings. Dunn had also worked on identifying the earliest animal lineages. He had seen King present the work at a conference and was interested in the results. But while digging through the data, he found some inconsistencies. He then worked with King and Steenwyk, who were dedicated to fixing the situation, Dunn says, to uncover the errors that invalidated the study’s conclusions. This gave him “a tremendous amount of respect” for the pair, he says. Breaking the silence In palaeontologist Christine Sosiak’s experience, speaking up about retractions can help others going through the same experience. Controversial ‘arsenic life’ paper retracted after 15 years — but authors fight back When Sosiak and her PhD adviser at the New Jersey Institute of Technology in Newark, palaeontologist Phillip Barden, realized that their paper claiming they had identified the oldest army ant fossil was based on a misdated specimen from a museum collection5, they knew they had to set the record straight. And issuing a retraction in the journal Biology Letters didn’t feel like enough. “I wanted to make sure that people knew about the retraction, and that I cleared the air as much as possible,” Sosiak says. So she announced the retraction on the social-media platform X. Afterwards, Barden and Sosiak, who is now a postdoctoral fellow at the University of Alberta in Edmonton, Canada, received an outpouring of support from their peers. Many of them even shared similar retraction stories. That made the situation easier to manage, says Barden. That’s not to say all the feedback received by researchers who self-correct is positive. King says she got a few negative comments that were hurtful. But the positive support outweighed the negative, she says. Oransky agrees that talking openly about cases like these helps to take the sting out of scientific errors — which is why he’s excited about the Ctrl-Z Award. Discussing mistakes is helpful for science as a whole, he says. It shows that “the scientific community does value this behaviour”.

Over the past five years, dermatologist Rajani Katta has noticed a change in the people who come into her office. Their skincare routines have been getting more complicated — some stretching to 12 steps — and often involve products that they found through social media, many of which don’t have a lot of scientific backing. The science influencers going viral on TikTok to fight misinformation They didn’t realize that some of those products were doing damage to their skin, says Katta, who specializes in sensitive skin and allergies at the University of Texas Health Science Center at Houston. “People are much more likely to experiment on themselves” than they have been in the past, she says. Globally, there seems to be more interest in skincare than ever before, with the industry expected to generate more than US$200 billion worldwide in 2026. Social-media platforms such as TikTok seem to be a main driver of the hot pursuit of youthful, glowing skin, with hashtags such as #SkinTok generating more than one billion views per month. The platforms have helped to kick-start a wave of skincare trends, from using beef tallow as a moisturizer to achieving ‘glass skin’ — a smooth, shiny complexion — using dozens of pricey products. They’re also rife with harmful misinformation, such as the false claim that sunscreens cause skin cancer and vitamin-D deficiency. For most people, the recipe for maintaining healthy skin should be simple and follows guidelines that dermatologists have offered for years. But it’s not just about what one puts on or takes off one’s skin. There’s plenty of evidence that lifestyle factors are important — arguably more important — than products and daily rituals for keeping skin healthy. Often, the recommendations from physicians about skin run counter to what is circulating on social media. What’s more, new research is elucidating the connections between the skin and other organ systems, and it has become clear that keeping skin healthy has effects far beyond one’s outward appearance, says Mao-Qing Man, a dermatologist at Hebei Medical University in Shijiazhuang, China. “Skin health is important for overall health,” he says. A dynamic organ The skin is the body’s suit of armour, acting as the first line of defence against the constant barrage of threats from the outside world, including pathogens, chemicals and ultraviolet radiation. “It has a lot of different dimensions,” says Daniel Kaplan, a dermatologist who focuses on immunology at the University of Pittsburgh in Pennsylvania. Skin is made up of three main layers: the hypodermis (bottom), dermis (middle) and epidermis (top). The epidermis constantly churns out fresh skin cells to replace the roughly 40,000 dead skin cells that the body sheds every day. The outermost layer of the epidermis is the stratum corneum, more commonly known as the skin barrier. This waterproof shield is made of corneocytes — flat, dead cells filled with the protein keratin. These tough cells are surrounded by lipids called ceramides, which lock in moisture and keep invaders out of the skin. The outer layer of the skin and its natural oils form a protective barrier.Credit: Thierry Berrod, Mona Lisa Production/SPL Although biology textbooks often compare the skin barrier to a brick wall, it’s more like a thriving ecosystem of physical, chemical, microbial and immune functions, says Peter Lio, a dermatologist who specializes in eczema at Northwestern University in Evanston, Illinois. “Our skin barrier is incredibly dynamic and complex,” he says. But, it’s also “pretty easy to screw it up”, Lio says. For instance, some popular cosmetic procedures, such as chemical peels — which temporarily remove the outer layers of the skin to reduce wrinkles and acne scars — can cause lasting harm to the skin barrier and result in chronic sensitivity if done incorrectly or too frequently. “The skin does have powerful abilities to regenerate”, but some treatments can override that, says Katta. The surprisingly big health benefits of just a little exercise Common signs of a compromised skin barrier include persistent dryness, itchiness and redness, along with acne and infection. This damage can increase a person’s risk of developing more chronic skin conditions, such as atopic dermatitis, psoriasis and even allergies, says Katta. It can also make it easier for pathogens such as Staphylococcus aureus, a bacterium that can cause abscesses and, in more severe cases, blood infections, to slip past the barrier. A common mistake that many people make at home is overusing harsh soaps, detergents and astringents — liquids that shrink body tissues by drawing water out of them, says Kaplan. These substances, which include alcohol and witch hazel, can be useful for removing excess oil, make-up and acne-causing bacteria. But they can also strip away the natural oils that keep the skin barrier intact in the first place, adds Kaplan. The barrier also has an acid mantle — a thin, filmy layer of oils, fatty acids and amino acids — which helps to keep the skin stable and creates the conditions needed for a healthy microbiome to flourish (see ‘A home for beneficial bacteria’). Wiping out lipids with harsh products raises pH levels. This, in turn, weakens the community of beneficial microorganisms and enables pathogenic types to flourish. Taking scalding hot showers is another way to damage the skin barrier, says Tamia Harris-Tryon, a physician scientist who studies the skin microbiome at the University of Texas Southwestern Medical Center in Dallas. “If it’s hot enough to clean your pots and pans of oil, it will clean your body of natural oils,” she says. Source: go.nature.com/4rigfrx Children as young as nine years old are becoming more interested in skincare products and multistep routines, says Lio. Whereas gentle cleansers, moisturizers and sunscreen are generally safe for kids, potent serums and anti-ageing products for mature skin can wreak havoc on younger skin, he says. The American Academy of Dermatology recommends washing the face twice a day with a gentle cleanser, applying a moisturizer and — during the day — putting on sunscreen and protective clothing. Shield against the Sun Over the long term, few things are worse for the skin than overexposure to UV radiation, either through natural sunlight or tanning beds, says Elsemieke Plasmeijer, a dermatologist and epidemiologist at the Netherlands Cancer Institute in Amsterdam. UV radiation is the leading cause of melanoma — the deadliest form of skin cancer. In 2022, almost 60,000 people died from melanoma, according to the World Health Organization’s (WHO) International Agency for Research on Cancer. The two main types of UV radiation that reach Earth’s surface — UVA and UVB —affect the skin in different ways. UVA causes damage in the dermis by triggering oxidative stress and breaking down collagen and elastin — proteins that provide tissues with structure and flexibility. Meanwhile, UVB only reaches the epidermis, but causes sunburn and DNA damage that can lead to skin cancer. A 2019 study found that both types of UV radiation disrupt a protein that helps cells to stick together in the skin barrier1. This resulted in weaker bonds between corneocytes, leading to a less resilient skin barrier. Stress is wrecking your health: how can science help? Sunbathing on the beach for hours isn’t the only way to get too much UV radiation. In December, Pedram Gerami, a dermatologist who specializes in skin cancer at Northwestern University, and his colleagues reported that people who use indoor tanning beds were three times more likely to get melanoma than those who don’t use them2. They were more likely to have multiple melanomas, even in parts of the body that usually have low levels of Sun damage, such as the thighs. The indoor tanning industry often argues that tanning beds are safer than natural sunlight because they emit more UVA than they do DNA-damaging UVB light. But this claim is often false, says Gerami. “The amount of UVA is about 10 to 15 times higher than the UVA outside,” he says. The WHO classifies tanning beds as a human carcinogen in the same category as asbestos and cigarette smoke. Several clinical trials with long-term follow-ups have shown that using sunscreen greatly reduces the risk of developing skin cancer, including melanoma3,4. The WHO recommends people use a broad-spectrum sunscreen — which blocks out both types of UV radiation — that has a Sun protection factor (SPF) of 30 or higher. But wearing protective clothing, such as long-sleeved shirts and wide-brimmed hats, provides the best protection, along with staying out of the Sun when it’s at its peak between 10 a.m. and 2 p.m., says Plasmeijer. Taking these extra precautions is important, particularly given that sunscreen quality can vary widely, she adds. Last September, for instance, several popular sunscreens in Australia were pulled from the shelves after tests conducted by the Therapeutic Goods Administration — the country’s drug regulator — revealed that they had a much lower SPF than they claimed because of problems with their base formulations. Despite the weight of evidence behind sunscreens, there is a flood of misinformation being spread by social-media influencers, including the baseless claim that sunscreens cause skin cancer and vitamin-D deficiency. Such falsehoods are often targeted at younger people who are not yet visiting dermatologists, says Plasmeijer. “It’s hard to debunk,” she says. Keep it simple Although there are thousands of skincare products on the market that promise to restore youth and reverse damage, many rely on ingredients that have little scientific evidence to back up their claims, says Lio. For instance, studies have shown that using a simple, well-balanced moisturizer can help to support and repair each layer of the skin barrier5. The most effective moisturizers contain three main components, says Lio. Emollients, such as oils, soften the skin and prevent water loss by filling in the gaps between skin cells and lipids. Meanwhile, humectants, such as hyaluronic acid, pull in moisture from the outside air or from the dermis to the surface of the skin, and occlusives, such as petroleum jelly, create a seal over the skin that prevents water loss. There are a handful of further ingredients that have research behind them and can help to address specific skin concerns, says Katta. One is retinoids, a group of compounds derived from vitamin A that are often used to treat acne, psoriasis and ageing. These molecules work by turbocharging cell turnover and collagen production, which in turns reduces wrinkles and dark spots. They also block several inflammatory pathways that exacerbate acne and slow down the breakdown of collagen that’s already present in the skin. “Retinoids are one of those hero molecules,” says Katta. Do smartphones and social media really harm teens’ mental health? Meanwhile, antioxidants such as vitamin C provide a protective boost against free radicals — unstable, highly reactive molecules that damage the skin’s lipids, DNA and proteins. A 2017 study of healthy adults found that applying vitamin C and other antioxidants to people’s forearms helped to prevent collagen- and elastin-damaging enzymes from being activated when they were exposed to ozone, a major component of air pollution6. No amount of moisturizer or high-powered molecules can counter the effects of an unhealthy lifestyle, however, says Giuseppe Valacchi, a regenerative-medicine researcher who focuses on skin at North Carolina State University in Kannapolis. For instance, smoking wreaks havoc by hindering the skin’s repair mechanisms, degrading collagen and elastin, along with reducing blood flow that carries nutrients to the skin. “You can put whatever you want on top of the skin, it won’t help,” says Valacchi. A big lifestyle component of maintaining healthy skin is eating a nutrient-dense diet with plenty of antioxidants, amino acids and fats, says Harris-Tryon. The skin, she says, is “the first place you can visually see that someone is nutrient deficient”. There’s also growing evidence that the skin and gut are deeply connected. Some studies have found that altering the gut microbiome changes inflammation signals in the skin, hinting that there could be a link between gastrointestinal health and skin disorders, such as psoriasis7,8. But the exact mechanisms are still being explored, says Harris-Tryon. As well as the skin being a window into internal health, it also contributes to overall health. Man and his colleagues have found in mice that wrinkly, ageing skin expresses more inflammatory molecules called cytokines than does younger skin, suggesting that skin could play a role in ‘inflammageing’ — the background inflammation that creeps up as people get older. In a small 2019 study9, the researchers also found that treating older people’s skin with an emollient reduced the levels of cytokines circulating in the bloodstream, suggesting that this might help to prevent age-related disorders that are linked to inflammation. Although there are a plethora of products and elaborate routines that promise seemingly flawless skin, maintaining healthy skin often demands a simple approach, says Katta. “When we think about the function of our skin, it’s not necessarily to look good,” she says. “It really is to protect us from outside forces.”

A computer generated illustration of a simulated cell in the early stages of division. Credit: Zane Thornburg For the first time, researchers have simulated nearly every chemical reaction in a living bacterial cell. The simulation models the virtual cell copying its DNA and dividing in two. The simulation could help researchers understand how interacting mix of proteins, nucleic acids, fats and other molecules within the wall of a cell gives rise to actual life, says Zane Thornburg, a computational biophysicist at the University of Illinois in Urbana-Champaign who co-led the 9 March study in Cell1. Virtual life To model bacterial life, Thornburg turned to one of its simplest examples: a bacterial cell with a ‘minimal’ genome. The organism, named JCVI-Syn3a, was created by whittling the genome of the parasite Mycoplasma mycoides down to just 493 genes, dispensing with more than 400 non-essential genes2. Thornburg created a three-dimensional simulation that attempted to account for the cell’s DNA, proteins, ribosomes and other molecules of life, as they change over time. Specific molecules, such as a DNA-copying enzyme, obeyed rules based on real-world measurements, and reactions occurred when interacting partners became close in physical space. Some details were fudged. For example, the functions of several dozen JCVI-Syn3a genes still aren’t known, so Thornburg’s team modelled them as inert spheres. Also, in real cells, multiple ribosomes can make protein using the same mRNA transcript, but Thornburg’s model allowed just one ribosome per transcript. The team’s goal was to simulate JCVI-Syn3a over the time it takes to copy its DNA and divide into two, known as the cell cycle. Some early attempts failed, Thornburg says, because the genome kept falling apart faster than it could be made, or spewing out of the cell membrane. After making tweaks to address such issues, they left the model to run over US Thanksgiving holiday in November. “We came back, and suddenly a whole cell cycle had run,” Thornburg says. “All of a sudden, it was just this huge leap.” The computer simulation recapitulated many details of actual life, including how the shape of the cell swells and elongates as it divides into two. The 105 minutes the virtual cell took to divide was “scarily close” to the time the cell takes to reproduce in real life, Thornburg says. Simulating those 105 minutes, however, took 6 days on a supercomputer, underscoring how computationally intensive such cell models are to run. Bernhard Palsson, a bioengineer at the University of California, San Diego, says the simulation is an important achievement because of the shear breadth of cellular activity it captures. “Getting all these processes to behave coherently during the cell cycle is a major challenge.” Alternative models Marinka Zitnik, a computational biologist at Harvard Medical School in Boston, Massachusetts, thinks the JCVI-Syn3a computer simulation could inspire separate efforts to use artificial intelligence to create ‘virtual cells’. The goal of AI virtual cells is to approximate the inner workings of cells by learning from vast quantities of cell-biology data, instead of encoding the detailed rules of biochemistry as Thornburg’s team did. To best reflect life, though, AI virtual cells will need to account for how cells change over time, as the JCVI-Syn3a model does. “This study establishes an important foundation for digital cell models,” Zitnik adds. However, Markus Covert, a bioengineer at Stanford University in Palo Alto, California, says that the JCVI-Syn3a simulation and ‘mechanistic’ models like it have distinct advantages over AI virtual cells — which some scientists say could be up to a decade away. Models such as the JCVI-Syn3a simulation and one Covert’s team are developing for Escherichia coli3 are less data-hungry than AI models, while insights gleaned from cell simulations are grounded in biochemical mechanisms that can be easily tested.“These models can lead us to scientific questions that were never considered before,” Covert says.

A medical team at Xijing Hospital of the Air Force Medical University in Xi’an, China, surgically connected a man with liver failure to an external, genetically modified pig liver. Credit: Xinhua via Alamy A 56-year-old man with liver failure has become the first living person to be surgically connected to a genetically modified pig liver, say the team that conducted the surgery. The pig organ filtered the man’s blood for a few days while he waited for a human liver transplant, they say. The man has since received a human liver and is recovering well, says Lin Wang, one of the surgeons who led the procedure in January at Xijing Hospital of the Air Force Medical University in Xi’an, China. Wang says his team plans to submit the results to a peer-reviewed journal. Proponents of transplanting genetically modified animal organs into people, a procedure called xenotransplantation, hope that the method could reduce the number of people who die while waiting for a human organ. At least a dozen people in the United States and China have received pig organs, including hearts, kidneys, livers and a thymus – and clinical trials are under way in both nations. But, organ transplants are high-risk surgeries and recipients must take immunosuppressants for the rest of their lives. In the latest surgery, the recipient was connected to a pig liver outside their body — a procedure called extracorporeal perfusion. The procedure is a bridging therapy that allows a person’s organs to recover, and it can be lifesaving for people who are too sick to wait for a human donor organ without intervention, says Wayne Hawthorne, a surgeon and transplant researcher at the University of Sydney in Australia. ‘Remarkable’ Extracorporeal perfusion using pig organs has been performed since the 1990s, but the development of genetically modified pig organs that are more compatible with people reduces the risk of organ rejection. A US team have connected at least four clinically dead people to external, genetically modified pig livers1. That surgeons in China have been able to do this in a living person is “a remarkable achievement,” adds Hawthorne. Muhammad Mohiuddin, a clinician-researcher at the University of Maryland School of Medicine in Baltimore, who led the first pig-heart transplant into a living person in 2022, agrees that the technology could be lifesaving. Hawthorne and Mohiuddin say they are eager to know more details about the surgery in China, including the amount of immune-suppressing therapy that was used, how the man’s health changed over time and how long could someone be connected to the external liver. Results of liver-function tests before, during and after the surgery will also be needed if the team publishes its findings, Hawthorne adds. “This is all the basics for a liver transplant paper.” The recipient in China had chronic hepatitis B infection, a serious liver illness, and damage caused by alcohol, which led to a sudden deterioration in his liver function, says Wang. He had been hospitalized in Shanghai, China, for a month before Wang’s team treated him. Without a donor organ available, the surgeons decided — with consent from the man and his family — to test whether a pig liver could take over the functions of his failing liver. The pig liver contained six genetic modifications, says Wang, and was supplied by the company ClonOrgan Biotechnology in Chengdu, China. The six genetic modifications included three deactivated pig genes and introduced three genes that produce human proteins, to reduce the risk of the recipient rejecting the organ. External filter The surgeons stitched tubes to a vein in the man’s leg, connecting him to a perfusion device containing the pig liver. His blood was redirected through the pig liver to remove harmful waste products that build up owing to liver failure. The physicians said that there were no signs that the organ was being rejected, and that the man’s own liver function began to improve. The man was disconnected from the perfusion system after nearly three days to reduce the risk of infection and complications. Megan Sykes, a surgeon and immunologist at Columbia University in New York City, says it is significant that the man in the latest study could be taken off the perfusion for several days while he waited for a human organ to became available. But it is unclear whether the man survived without the external liver because his own liver began to recover or the benefits of being connected to the perfusion system persisted. “I can’t say from the information that was provided,” she says. Last year, the US Food and Drug Administration approved a trial to test whether extracorporeal perfusion using genetically modified pig livers can safely treat people with organ failure. Mike Curtis, the chief executive of eGenesis, which is based in Cambridge, Massachusetts and is one of the bioengineering companies running the trial, says the trial is still recruiting participants.

The past three years have been the warmest recorded on Earth.Credit: Raj K Raj/Hindustan Times via Getty The rate of global warming has surged since 2015 and is now nearly double what it was in the 1970s, according to a study1 that tackles one of the hottest debates among climate scientists. Because the past three years have shattered temperature records (see ‘Temperature boost’), researchers have been exploring whether global warming is accelerating, and if so, why. Many scientists agree that the rate at which it is increasing has picked up. This is mainly because of a reduction in air pollution following the introduction of fuel regulations for international shipping (which has resulted in fewer pollutant particles that reflect sunlight into space and seed insulating clouds). In the data, “you can practically see by eye that it has accelerated”, says Stefan Rahmstorf, a climate scientist at the Potsdam Institute for Climate Impact Research in Germany. Source: Copernicus Climate Change Service/European Centre for Medium-Range Weather Forecasts. Rahmstorf and Grant Foster, a statistician in Orono, Maine, say they have the strongest evidence yet that global warming has sped up, to a rate of around 0.35 ºC per decade. That’s faster than some other estimates2. But, the pair say their analysis captures a more accurate picture because of the way it accounts for and removes the effects of natural factors, such as weather events and volcanic eruptions, that cause climate fluctuations. The study was published today in Geophysical Research Letters1. Accounting for nature The analysis removes the impact of the powerful El Niño weather phenomenon that contributed to record-high global temperatures in 2023 and 2024. Even with that subtracted from the data, the acceleration of warming is clear, Rahmstorf says. Their research took five of the most widely used global temperature data sets into consideration, including one produced by NASA (see ‘Rate hike’). Global temperatures have been soaring as people burn fossil fuels and release heat-trapping gases into the atmosphere. By 2030, the planet is on track to breach — and stay above — the threshold of the 2015 Paris agreement: 1.5 ºC above pre-industrial levels, Rahmstorf says. Source: Ref. 1. Other studies have also argued that global warming is accelerating3. One commonly cited estimate holds that the rate of change is now 0.27 ºC per decade, compared with around 0.20 ºC per decade in the 1970s2. Not everyone agrees with the latest estimate of a rate of 0.35 ºC per decade. Climate scientist Zeke Hausfather at Berkeley Earth, a non-profit organization that tracks global temperatures, in Berkeley, California, says the authors’ methods for removing natural fluctuations are “imperfect and will leave some remaining effects”. Robert Rohde, chief scientist at Berkeley Earth, says he estimates that the current warming rate is more like 0.30 ºC per decade. Still, Hausfather and Rohde note that most climate scientists agree that warming is indeed accelerating, emphasizing the urgency of addressing climate change. “We have to really prioritize emissions reductions — we have even less time now that the rate of warming has accelerated,” Rahmstorf says. Regional hotspots Global warming is causing storms, floods, droughts and other weather events to become more extreme. In 2025, millions of people around the globe were displaced owing to such events, according to World Weather Attribution, an international research group. Another study4, which was posted on a preprint server ahead of peer-review, suggests that global warming could be accelerating faster in specific areas of the world than others. Claudie Beaulieu, a climate scientist at the University of California, Santa Cruz, and her colleagues used five global temperature data sets to analyse specific regions around the world. They could not confirm a global acceleration, but found hotspots of accelerated warming, including southeast China and southeast Mexico. Those results, although preliminary, could be consistent with the fact that China and Mexico have said they are cleaning up air pollution, the scientists write — therefore pollutants that had suppressed much of the warming might now be gone.

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Injections that reduce weight and treat diabetes could also cut the risk of dying from substance-use disorders.Credit: Jill Connelly/Bloomberg/Getty Blockbuster GLP-1 medications might help people to avoid becoming addicted to drugs, including alcohol, cocaine and opioids, a massive study1 suggests. It also found that, for those already dealing with addiction, the treatments are linked to a 50% reduction in the risk of dying from substance abuse. The findings, published today in The BMJ, come from an analysis of electronic health records from more than 600,000 people in the database of the US Department of Veterans Affairs (VA), which provides care for millions of military veterans. The study is the latest suggesting that GLP-1 drugs — which mimic a hormone called glucagon-like peptide 1 and are mainly prescribed to treat obesity and type 2 diabetes — can also play a part in curbing addiction. Why do obesity drugs seem to treat so many other ailments? The study’s large number of participants is unique and allowed researchers to evaluate the effect of GLP-1 drugs on the risk of several substance-use disorders. “The consistency of effect across multiple substances, which have different mechanisms of action, was quite a revelation,” says Ziyad Al-Aly, a co-author and a clinical epidemiologist the VA St Louis Health Care System in Missouri. The observational study confirms what physicians are seeing in their clinics and the results of some small clinical trials2. But larger clinical trials are still needed to demonstrate whether the drugs could truly help people with substance-use disorders, specialists say. “We have our patients telling us, ‘I don’t feel like I want to smoke anymore. I don’t really have the interest in drinking anymore,’” says Daniel Drucker, an endocrinologist at the University of Toronto in Canada. “There’s no question this is real and there are responders. But, so far, we don’t have a really robust, randomized, controlled clinical trial.” Treasury of data Intrigued by peoples’ reports of reduced alcohol cravings while taking GLP-1 drugs, Al-Aly turned to the VA’s database of electronic health records. “It’s a colossal data system and it creates a great opportunity,” he says. Al-Aly and his colleagues used the database to compare two groups of people with type 2 diabetes: the treatment group, which had been prescribed GLP-1 drugs, and the control group, which had been prescribed a different class of diabetes medication, called sodium-glucose cotransporter-2 (SGLT-2). They were followed for up to three years after they began taking either medication. Anti-obesity drug has life-changing benefits for arthritis Among the GLP-1 users with no history of addiction, the risk of developing a substance-use disorder over the three-year period was 18% lower for alcohol, 14% lower for cannabis, 20% lower for cocaine, 20% lower for nicotine and 25% lower for opioids than among those in the control group. Among participants who had a history of substance-use disorders at the start of the study, those taking a GLP-1 drug generally had a reduced risk of the substance-use complications measured in the study than did those in the control group: a 50% lower risk of dying, a 31% lower risk of visiting the emergency department and a 36% lower risk of being admitted to hospital. Dopamine hit The reduction in mortality associated with substance use was “incredibly striking and encouraging”, says W. Kyle Simmons, a pharmacologist at the Oklahoma State University in Tulsa. He adds that the inclusion of a control group is an important feature. Because both types of drug “have positive effects on diabetes and systemic health”, the control group’s results strengthen the idea that the anti-addiction effect is related to the action of the GLP-1 drug in the brain, rather than general health benefits, Simmon says. It’s not clear how GLP-1 drugs might curb addiction, but the fact that they seem to have this effect across different substances suggests that they are acting on a common mechanism, Simmon adds. The most likely option, he says, is the brain network that uses the neurotransmitter dopamine to reinforce pleasurable experiences and, in some cases, drive cravings. Alcohol and cancer risk: what you need to know Al-Aly says that, although the results are encouraging, people with substance-use disorders should not take these drugs without advice from their doctor. He adds that more research is needed before GLP-1 drugs can be prescribed to treat addictions in people without obesity, diabetes or another approved indication. For example, it’s unclear whether the drugs could cause dangerous weight loss in those populations. Several randomized clinical trials, including one led by Simmons focusing on alcohol use, are underway and are expected to report results this year. “In the next six months, a lot is going to be revealed about the efficacy and safety of these drugs” as treatments for substance-use disorders, says Simmons. “And that will then motivate the next generation of studies that will hopefully drive us towards” things such as approval from the US Food and Drug Administration.

Credit: Denis Charlet/AFP via Getty An identical twin commits a crime and leaves their DNA at the scene. Can DNA testing reveal which twin is the culprit? This question reportedly came up in a case in France last month, where the DNA of twin brothers was found on a gun, but conventional DNA testing could not determine which of the brothers it belonged to. The men are monozygotic twins — the result of a single egg splitting in two after being fertilized by a single sperm — meaning they have the same DNA. When DNA is found at a crime scene, forensic scientists typically attempt to identify the person it belongs to using a technique called short tandem repeat (STR) analysis. The technique uses the polymerase chain reaction (PCR) method to amplify up to 30 specific regions of the genome that have a lot of genetic variation, says Brendan Chapman, a forensic scientist and researcher at Murdoch University in Perth, Australia. These amplified regions are sequenced to determine the number of STRs and their base pair patterns, which can then be compared to genealogy databases or STR profiles of suspects to identify any potential matches. Ordinarily, Chapman says, “we can differentiate one person from the next very easily”. But with monozygotic twins, “there just is no difference” in those regions of the genome. Deep dive Whole-genome sequencing can make it possible to tell identical twins apart. By analysing the entirety of a person’s genome, scientists can identify differences caused by mutations that occurred after an egg split. These changes are rare, says Chapman. For instance, a 2014 study identified just five genetic changes between a pair of adult twins1. There have been rare cases in which sequencing of the entire genome has helped courts to distinguish between twins, says Xanthé Weston, a criminologist and researcher at Central Queensland University in Mackay, Australia. But using whole-genome sequencing requires sufficient amount of DNA to analyse, adds Weston. Other researchers have reported success in distinguishing between twins by sequencing DNA found in the mitochondria, the powerhouses of cells. Compared with nuclear DNA, which is used in genome sequencing and STR analysis, mitochondrial DNA (mtDNA) mutates more often, meaning it is more likely to differ between twins. US courts have admitted mtDNA analysis as evidence since the mid-1990s. But it has not been used in cases involving twins, says Weston. 'Epigenetic' changes Another promising technique looks at the addition of methyl groups to DNA, a process called methylation, which can change how genes work. These ‘epigenetic’ changes can be caused by factors including a person’s behaviours — such as their diet and drinking or smoking habits — and their environment. Last year, a team of scientists in South Korea sequenced the genomes of 54 pairs of newborn monozygotic twins. After identifying 711 sites at which methylation commonly differed, they selected and tested various combinations and 5 that were particularly variable. By comparing how much methylation had occurred at these five sites, the team was able to differentiate between 50 of the 54 pairs of twins2. When they repeated the experiment in two adult cohorts, they succeeded in differentiating between 41 of 47 pairs and 105 of 118 pairs of twins. DNA-methylation analysis has not yet been used to distinguish between twins in court. And Chapman notes that this kind of analysis might not be able to distinguish between twins who have similar variations caused by leading similar lifestyles or being exposed to similar environmental factors such as pollution. Challenges remain The new techniques are promising, Chapman adds, but there are challenges to overcome before they can be used in forensic investigations. For instance, they all require relatively large amounts of DNA, but samples from crime scenes often comprise only small amounts of DNA or samples in poor condition. Analyses can also be expensive and time-consuming, partly because of the work needed to demonstrate to a courtroom that the results are conclusive enough to be counted as evidence. Last year, whole-genome sequencing was admitted in a US murder trial for the first time. Weston says that it is important to combine DNA evidence with other types of evidence, such as fingerprints, when prosecuting someone, because there are many reasons why someone’s DNA might be present at a crime scene. “I would never want to see somebody prosecuted on the basis of DNA alone,” she adds.