Daily briefing: COVID’s origins — what we do and don’t know

Nature News · Feb 24, 2026 · Collected from RSS

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NATURE BRIEFING 24 February 2026 Most peer-reviewed evidence suggests an animal origin of SARS-CoV-2, but doesn’t indicate when or where the spillover occurred. Plus, how horses can make two sounds at once at the science jobs that might be overtaken by AI. By Flora Graham Flora Graham You have full access to this article via your institution. Hello Nature readers, would you like to get this Briefing in your inbox free every day? Sign up here.Whinnies seem to play a part in horses’ social interactions. Credit: Mumemories/GettyHorses’ whinnies are two-in-one soundsHorses (Equus ferus caballus) make the noise of their characteristic whinnies by producing two sounds at once: a low-frequency sound made in their vocal folds, and a high-pitched whistle produced by forcing air through the cartilage of their larynx. This ability makes horses one of a small group of animals that can make two-toned sounds, including several bird species and human beat boxers and throat singers. Researchers theorize that this multilayered vocalization enables horses to convey complex messages to each other.Nature | 5 min readReference: Current Biology paperThe science jobs under fire from AIArtificial intelligence tools are already reducing demand for jobs that involve writing code or doing basic data analysis, researchers tell Nature. For example, research programmer roles — dedicated to creating scientific software and tools — “are now obsolete,” says computational biologist Brian Hie. Some scientists warn of potential dangers if the loss of such jobs removes the stepping stones for early-career researchers. “You might temporarily get more research per dollar,” says computational biologist Claus Wilke, “but the cost would be a collapse of your pipeline and long-term decline”.Nature | 6 min readUS$120,000The ‘motherhood penalty’ — the loss in income during the two decades after first becoming a mother — in Denmark, 80% of which is offset by the country’s generous childcare and parental-leave policies. (Nature | 6 min read)Reference: European Sociological Review paperJapan moves to approve stem-cell treatmentsJapan’s health ministry has endorsed issuing conditional approval for two first-of-a-kind medicines made from reprogrammed stem cells. The therapies, one for the treatment of Parkinson’s disease and the other for severe heart failure, have shown promise in clinical trials, but have only been tested in 7 and 8 people, respectively — far fewer than is needed to ensure the treatments are safe and effective, say researchers. “This is a risky regulatory experiment,” says stem-cell researcher Paul Knoepfler. “It feels like early days to be talking about commercialization of such products.”Nature | 6 min readIron Age grave reveals gender-based violenceA mass grave from a ninth-century bc site in Serbia has been revealed to contain the bodies of dozens of women and children who died in targeted attacks — an unprecedented case of gender-based violence in the early Iron Age. The findings give clues to shifts in power and gender relations in Iron Age Europe, a period marked by frequent population movements. The study’s authors speculate that many of the victims were part of migrating communities drawn to new lands or were experiencing forced migration or displacement.Nature | 4 min readReference: Nature Human Behaviour paperFeatures & opinionInside China’s assault on Alzheimer’sChina’s ageing population means that something like 66 million people could be living with dementia there by 2050 — an estimate that is driving the country to push research forward. Scientists have been working on new drugs and innovative — if controversial — surgical techniques. The government has also encouraged the development of treatments derived from traditional Chinese medicine. And researchers are accelerating the search for biological markers that precede the onset of Alzheimer’s disease to help identify it earlier.Nature | 9 min readScientists can stand against nuclear armsThe expiration of the New START treaty between the United States and Russia has put the world into an even more precarious era of escalating nuclear risks, writes physicist Karen Hallberg, who leads the Pugwash Conferences, a nuclear-disarmament group sparked by Albert Einstein and Bertrand Russell. “US and Russian leaders can take unilateral action by simultaneously committing to observe a one-year moratorium on exceeding the treaty’s established limits and parameters,” she writes. “Researchers can also have a crucial role in maintaining diplomatic channels and keeping lines of communication open between opposing parties.”Nature | 7 min readCOVID’s origins: what we do and don’t knowAfter more than three years of deliberations, a World Health Organization advisory group last year concluded its independent assessment of how the COVID pandemic started. “Most of the peer-reviewed scientific evidence supports the hypothesis that SARS-CoV-2 has a zoonotic origin, meaning that it came from an animal,” write 23 of the 27 original members in a Nature Comment article reflecting their personal views. “But until requests for additional information are met or more data become available, there can be no certainty about when, where and how SARS-CoV-2 entered the human population.” There is a continued need for a thorough, unbiased investigation, they say — and the longer we wait, the harder it will be to find firm answers.Nature | 19 min read doi: https://doi.org/10.1038/d41586-026-00609-6Add birdwatching to the list of hobbies — such as learning a language or how to play an instrument — that might protect against age-related cognitive decline. That’s good news for the people whose Google data powers a beautiful interactive visualization by Nadieh Bremer that reveals how people in the United States search for birds.While I look to the skies, why not send me your feedback on this newsletter? Your e-mails are always welcome at briefing@nature.com.Thanks for reading,Flora Graham, senior editor, Nature BriefingWith contributions by Jacob Smith• Nature Briefing: Careers — insights, advice and award-winning journalism to help you optimize your working life• Nature Briefing: Microbiology — the most abundant living entities on our planet — microorganisms — and the role they play in health, the environment and food systems• Nature Briefing: Anthropocene — climate change, biodiversity, sustainability and geoengineering• Nature Briefing: AI & Robotics — 100% written by humans, of course• Nature Briefing: Cancer — a weekly newsletter written with cancer researchers in mind• Nature Briefing: Translational Research — covers biotechnology, drug discovery and pharma Related Articles Daily briefing: New AI drug-discovery engine is ‘on the scale of an AlphaFold4’ Daily briefing: ‘Universal’ vaccine protects mice from multiple pathogens Daily briefing: Automated robot ‘scientists’ spark debate over the future of lab work Daily briefing: What we know about autism and ageing — and what we don’t