Innholdsfortegnelse for January/February 2025 i Discover

IT’S A TOUGH TIME to be a glacier. Scientists expected Venezuela’s Humboldt Glacier to survive another decade, but in 2024, its rapid melting downgraded it to an ice field, having now shrunk to an area of less than 2 hectares. The demise of the country’s last glacier signals a disturbing future ahead for the remaining glaciers around the world: They could be next. “We’ll lose the last tropical glacier in Asia over the next two years or so,” says James Kirkham, a chief science adviser at the International Cryosphere Climate Initiative, a network of scientists who study ice ecosystems. “Then, countries like Germany and Mexico will lose theirs.” As the burning of fossil fuels accelerates global temperatures to unprecedented highs, people who rely on freshwater from glaciers must confront new…

AT LEAST one climate-change-denying news site rejoiced when a commission of geologists voted in 2024 to reject a novel epoch called the Anthropocene. “Kudos to the geologists!” wrote the author, suggesting that environmentalists would cling to the term “to forward their antihuman stances and to blame all ‘bad things’ on humans and human influences.” But that attitude ignores the reason a group of geologists pursued a new geological epoch in the first place. The Earth’s 4.6-billionyear span, full of rocks and fossils and extended spells of climate change, has led us to the present Holocene Epoch, which started some 12,000 years ago. The Holocene is largely characterized by a relatively stable climate that allowed humans to flourish. The planet is many things these days, but “stable,” perhaps not. Rising global…

LARGE LANGUAGE models, or LLMs, like the artificial intelligence (AI) behind ChatGPT, can wield and comprehend human languages with remarkable fluency. Th ose abilities might also allow the technology to write in a very different, and potentially more profound, language: the letters of life itself. Berkeley, California-based startup Profluent is developing AI models based on the same fundamental concepts as ChatGPT. But rather than combing through repositories of language, these models are trained on datasets of proteins, biological molecules that do everything from break down food to spool up our DNA. One of the startup’s first AI-designed proteins powers a brand new version of CRISPR, the bacteria-derived gene editors that have revolutionized genomics. CRISPR proteins act like tiny bits of machinery that can snip apart the double helix of DNA…

THE QUEST TO make cross-species organ transplantation, or xenotransplantation, a practical reality took a major step forward in March, when surgeons at Massachusetts General Hospital transplanted a kidney from a genetically engineered pig into a patient with end-stage renal disease — the first time an animal kidney had been successfully transplanted into a living human. Although the recipient, 62-year-old Richard Slayman, died of a cardiac event seven weeks later, tests showed that the kidney was still functioning perfectly. The donor animal was provided by the biotech company eGenesis, which removed three pig genes and inserted seven human genes to prevent rejection. Even with these edits, Slayman’s immune system began to attack the kidney after a few days — a common occurrence with human-to-human transplants, as well. Doctors were able to…

IN THE 1930S, a paleontologist spotted a strange molar in an apothecary in Hong Kong. Sitting amongst a trove of fossils (dubbed “dragon bones” in traditional Chinese medicine), the molar looked a lot like an orangutan tooth, only double in size, indicating it belonged to an unknown species of giant ape. Since then, researchers have recovered nearly 2,000 teeth and four lower jawbones attributed to the species, Gigantopithecus blacki, from cave deposits in southern China thought to be between 2 million and 330,000 years old. To date, no skulls or other bones from the species have surfaced. “Everything we know now about Gigantopithecus is based on the teeth and the jaw,” says Yingqi Zhang, a paleontologist at the Chinese Academy of Sciences. Based on these chompers, Gigantopithecus has earned the…

Jane was seeing me in clinic for a follow-up visit when she first told me about her husband, Milo. I had recently treated Jane when she was in the hospital with jaundice and had removed an obstructing stone from her bile duct. But rather than talk about herself and how she was feeling, she kept refocusing the visit on Milo, who was sitting next to her. “I have been married to this man for 28 years and something is clearly wrong with him. He does not even resemble the man I knew anymore. He’s totally transformed over the past year,” she told me. When I pressed her for details, she was forthcoming. “Milo has worked in construction since before I met him, and he was literally indefatigable. Now, he’s sick…

IN MARCH, astronomers unveiled an historic new image of Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way galaxy. The image, which was captured by the Event Horizon Telescope (EHT) collaboration using polarized light, shows for the first time strikingly ordered magnetic fields swirling around the black hole, which lies approximately 27,000 light-years away. The spiral structure of those magnetic fields closely resembles something seen in a 2021 image also captured by the EHT, circling the edge of the much bigger black hole at the heart of elliptical galaxy M87. Previous studies of M87 suggest the magnetic fields help the black hole, a behemoth with 1,500 times the mass of our own, blast high-radiation jets into space. The researchers were surprised to see similar…

HAVE YOU ever wanted to examine the skeleton of Thailand’s cave angelfish? Or the bony plates of the African spiny mice? Or how about a rare Rim Rock crowned snake that died trying to eat a centipede? Now, 3D models of these organisms are available online for you — and the rest of the public — to download and marvel at. In March, scientists with the Florida Museum of Natural History announced the online publication of over 13,000 CT scans of vertebrates, uploaded in an effort to digitize museums’ specimen collections and make them more widely available. A network of 25 institutions came together in 2017 to build the project, called openVertebrate (oVert for short). The free archive features some specimens that are over a hundred years old and others…

WITH A NEW release of over a quartermillion genomes, a National Institutes of Health (NIH) program took a big step this year toward addressing pervasive inequities in the field of genomics. Since the first human genome was sequenced in 2003, scientists have added hundreds of thousands of genomes to databanks, hugely expanding our understanding of the breadth and complexity of human DNA. Yet despite that work, genomics repositories are still overwhelmingly populated by people of European descent, an issue that’s drawn criticism for years. “Genetics worldwide has been really nondiverse,” says Josh Denny, a physician and CEO of the NIH’s All of Us Research Program. A 2016 analysis published in Nature found that 80 percent of people included in large genomics studies were of European descent, leaving a scant 20…

CENTURIES AGO in England, a well-to-do woman sat for a portrait (at right). She wore her finest frock and held her pet: a handsome squirrel, leashed with a silver chain. Unbeknownst to pet or owner, a pernicious disease could’ve been transmitted. In a paper published in May in Current Biology, researchers found DNA from leprosy-causing bacteria in the bones of both medieval humans and squirrels, suggesting the disease once jumped between the two species. The research was inspired by work from the mid-2010s, which identified leprous squirrels living in the British Isles. Genetic testing on those from England’s Brownsea Island found that they carried Mycobacterium leprae, one of two bacterial species known to cause leprosy. Though the squirrels’ bacteria differed from the M. leprae that infects humans with leprosy today,…

IN 2018, neuroscientist Yina Ma was at a ceremony at Beijing Normal University when the crowd began to sing the school’s anthem. Shouting along, she says she felt a flash of pride toward the university, where she works as a professor, and a connection to those in the crowd she sensed felt the same way. The moment left a lasting impression, she says, inspiring her interest in brain synchronization. “Something special must have been happening in our brains,” Ma says. Scientists have been thinking about that “something special” since the 1960s. But it wasn’t until the 2000s that they systematically showed that people’s brains can coordinate in a phenomenon called “interbrain synchrony.” Specifically, through the simultaneous scanning of several brains at once, they revealed that as individuals interact, their neural…

IN EARLY JUNE, after circling the moon for nearly three weeks of scanning the surface for the perfect landing spot, a small probe separated from its spacecraft and began its descent. At about 100 feet above the surface, its laser 3D scanner identified obstacles to avoid. It landed gently on the side of the moon that faces away from Earth, which is craggier than the side that we see, in the southern part of the Apollo crater, a wide and flat region. The Chang’e mission was sent to the moon by the Chinese National Space Administration, and takes its name from a goddess in Chinese mythology who drank the elixir of immortality and flew to the moon to live eternally in the Moon Palace. The Moon Goddess, Chang’e, is celebrated…

BILLIONS OF people live along the planet’s shorelines. These areas are already under threat from rising sea levels caused by global climate change — but that might not be the only way humans are impacting cities along our shores. Recent studies looking at the U.S. and China show that the nations’ coasts are sinking at an alarming rate, potentially putting hundreds of millions of people and some of the world’s largest cities in peril. Subsidence, or sinking land, is nothing new. The main reasons for human-caused subsidence include the weight of buildings, removal of groundwater for public and industrial use, extraction of oil and gas from underground, and compaction of fill to make “new land” along a coast. Groundwater removal is especially impactful: Areas with large populations need lots of…

ALL THINGS must end, even something as seemingly constant as an ocean. When the supercontinent Pangaea began to break up over 175 million years ago, the Atlantic Ocean was born. The spreading of the ocean is still evident with volcanic eruptions in Iceland, which sits astride the Mid-Atlantic Ridge, but researchers are now seeing hints at the ocean’s ultimate demise. In fact, an “invasion” from the Mediterranean Sea might be the phenomenon that marks the beginning of the end. Oceans open due to tectonic plates breaking and moving away from each other. However, they eventually close due to subduction, the process by which pieces of Earth’s crust get shoved back into the planet’s ductile mantle. Oceanic crust is cold and dense compared to the mantle, causing it to “sink” through…

FOR DECADES, scientists have struggled to unlock one of the biggest enigmas behind allergies — why they don’t just go away. How they get started has long been understood. The immune system mistakenly overreacts to a harmless substance, producing antibodies known as immunoglobulin E (IgE). Those antibodies signal immune cells to attack the supposed invader with inflammatory chemicals, resulting in symptoms ranging from mild sniffles to potentially deadly anaphylactic shock. But how does the body remember what it’s allergic to so that it produces IgE whenever exposure recurs? In February, two groups of researchers revealed the keeper of that crucial data: a previously undetected type of memory B cell. Ordinary memory B cells produce IgG antibodies, which help the immune system recognize antigens such as bacteria and viruses. Although previous…

SCIENTISTS HAVE long believed that the immune system regulates its own activity, without needing supervision by the brain. Yet in a study published in May in Nature, researchers showed that assumption to be wrong. The discovery, experts say, could someday enable improved treatments for diseases in which an out-of-control immune response plays havoc with human health. The team, led by neuroscientist Charles Zuker and neuroimmunologist Hao Jin, found that a group of neurons in the brainstem acts as a master controller of inflammation. The cluster essentially presses or releases the brakes in response to signals from the vagus nerve — a network of fibers long known to link the body with the brain in governing processes such as digestion, respiration, and heart rate. “It’s easy to envision the brain getting…

WE THINK of Alaska as a gateway to the Arctic tundra, dotted with permafrost and dusted with dry snow, spotted with flora and fauna, and doused in summertime sun. But while Alaska has always been awash in wildlife, during the Age of Dinosaurs it would have been warmer, wetter, and a lot more tropical. In a study published in January 2024 in Geosciences, Anthony R. Fiorillo, the executive director of the New Mexico Museum of Natural History & Science in Albuquerque and a paleontology research professor at Southern Methodist University, reconstructed what an Alaskan ecosystem would have looked like some 100 million years ago, during one of the warmest periods in Earth’s history. Bursting with life in a climate thick with humidity, the mid-Cretaceous ecosystem, now locked away in the…

HANS BERGER had hit a standstill in his research when he rigged up one of the most important innovations of the 1900s. Absorbed by the mysteries of the mind, he had set out to study the strange, illusory “science” of telepathy. Attaching electrodes to a human head and connecting them to an apparatus that measured electricity, the psychiatrist performed the first electroencephalogram (EEG) in 1924, observing brain oscillations, or waves, in a human for the first time. A century later, scientists are still studying these waves and their significance, debating their movement as well as their meaning. While some researchers say they’re a stationary occurrence, others think they travel throughout the brain. And while some speculate they’re a byproduct of brain activity, others suspect they’re a driver, directing our thoughts…

Almost 140,000 neurons appear in this complete connectome, or brain wiring diagram, of an adult fruit fly. Members of the FlyWire consortium, a community of hundreds of scientists and citizen scientists from around the world, compiled the connectome from around 21 million images of a female fly. Though it isn’t the only wiring diagram to attract attention this year (see pages 44–45), it stands out as the first to map the whole brain of an adult fly — or any adult animal of such complexity. Published in a series of papers in Nature in October, the map marks an important milestone in neuro science and demystifies the brains of both flies and humans, as the thousands of neurons in one aren’t all that different from the billions of neurons in…