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It’s a debate that seems nearly as old as its subject: How did the Grand Canyon, that most charismatic of megalandscapes, come to be?

New evidence published today in Science , suggests some 6.6 million years ago, the Colorado River, which had not yet reached the sea, began to empty into a deep lake just upstream of the future Grand Canyon. Once these waters rose high enough, they could have overtopped a high plateau that blocked their westward progress. Like water breaching a dam, the event would have released a torrent that over time carved the canyon.

The clues, from lake-bottom sediments and outcrops that could mark the ancient shore, are “clear evidence that the lake existed and it was fed by the Colorado River,” says co-author Ryan Crow, a geologist at the U.S. Geological Survey. “The lake must have played a major role in the formation of the Grand Canyon.” Rebecca Flowers, a geochronologist at the University of Colorado (CU) Boulder, says Crow and his colleagues “make a reasonable case that lake spillover can explain the data,” but it’s still possible the water took a different route.

It’s long been known that the Colorado sculpted the Grand Canyon in its modern form, with its sediments appearing downstream of the canyon as recently as 4.8 million years ago. Its role has remained secure even as geologists have come to think that some parts of the canyon are far older, carved by earlier rivers as long as 70 million years ago, in the age of the dinosaurs.

But ever since John Wesley Powell’s 1869 expedition , the central question has been how the Colorado managed to reach the Grand Canyon at all—given that its path cuts straight across the Kaibab Plateau, the highest region in this part of the Colorado Plateau, which should have blocked its westward flow.

Early geologists proposed that a westward flowing river already existed when tectonic forces lifted the Colorado Plateau. As the terrain rose, the river cut its way backward through the plateau—eroding upstream until it captured the Colorado. Later work pointed to a different scenario: that the river system formed in the opposite direction, advancing from east to west in a series of “fill and spill” stages, as water pooled in basins and overtopped their rims.

One of the largest of those lake basins lies just east of the Kaibab: the Bidahochi Basin. If the ancient Colorado flowed into the basin and the water rose high enough, it might have spilled over the Kaibab and carved westward. But there was no evidence the Colorado fed the Bidahochi, and shoreline markers showed the lake only reached about 2000 meters in elevation—roughly 300 meters too low to overtop the Kaibab.

Two co-authors on the new paper, John Douglass of Paradise Valley Community College and Brian Gootee of the Arizona Geological Survey, took a new look at a mesa at the edge of this paleo-lake. There, they identified outcrops of beachrock—shoreline deposits turned to stone—at elevations of 2250 meters, close to what was needed to surmount the Kaibab.

Still, they needed evidence that the proto-Colorado had filled the basin. To get it, Crow and the other co-authors sampled the Bidahochi sandstones—rock formed from the lake-bottom sediments—at 19 sites. They dated some 3600 zircon mineral crystals trapped in the rocks by measuring the radioactive decay of trace amounts of uranium into lead. Zircon ages can serve as a river’s fingerprint because they reflect the upstream rocks that were the source of the sand. About 6.6 million years ago, that fingerprint abruptly shifts to match the Colorado’s. At the same time, the amount of sand entering the basin surged.

The study makes a compelling case that the Colorado filled the Bidahochi, Flowers says, but it doesn’t prove the spillover scenario. The Colorado might have reached the canyon when water from a shallower lake tunneled beneath the plateau, or when a river west of the plateau gradually cut upstream through it.

Matthew Heizler, a geochronologist at the New Mexico Institute of Mining and Technology, questions whether the Bidahochi outcrops represent a past beach. Yet in a forthcoming paper, he and his colleagues report new evidence that links the basin to the canyon: minerals in downstream river deposits that indicate Bidahochi sands entered the river by 4.8 million years ago. “It’s the best smoking gun I’ve seen in terms of making this connection,” he says. The researchers argue that notches in the Kaibab would have allowed waters in the Bidahochi to reach the canyon without rising as high as Crow and his co-authors claim. But neither group knows exactly what happened during the nearly 2-million-year-long gap between the Bidahochi filling and its sediments first appearing in the canyon.

The new picture of the canyon’s origins also leaves open the question of where the upper Colorado flowed before reaching the Bidahochi, adds Jon Spencer, a geologist at the University of Arizona who reviewed the Science study. Fish fossils in the basin resemble species found in ancient Lake Idaho, hinting that the river once drained northward into the Snake River system and flowed toward the Pacific Northwest—before volcanic activity associated with the Yellowstone hot spot rerouted it south.

For Crow, contributing to the story of the canyon’s origin is a homecoming of sorts. Before becoming a scientist, he worked at CU, creating interactive displays for the public—including one on the Grand Canyon. It was a river trip down the canyon that made him want to become a geologist. “I was blown away,” he says. He hopes future visitors will be inspired to learn a new story about its creation. “People seem to be interested in geology when they’re in front of the Grand Canyon,” he says. “It’s a teachable moment.”

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For decades, biology textbooks have enshrined a simple rule: DNA is made by copying a template. After one enzyme unzips a DNA double helix into separate strands, another called a polymerase builds a complementary sequence, base by base, for each strand. Presto: two copies of the original DNA. But new research into how bacteria defend themselves from viruses now shows this synthesis rule isn’t absolute. Today in Science , a Stanford University team describes a bacterial enzyme that synthesizes DNA without a nucleic acid template, using its own structure as a guide.

“The research is groundbreaking,” says Philip Kranzusch, a biochemist at Harvard Medical School who studies bacterial defenses. “Pretty cool!” adds Adi Millman, a computational biologist at the Massachusetts Institute of Technology. The use of a protein as a template for DNA synthesis, she says, “is a meaningful conceptual shift from the classical central dogma,” in which information flows in one direction from nucleic acids like DNA to protein. Scientists hope the novel form of DNA synthesis can be adapted as a tool for basic biological research, much like the powerful genome editor CRISPR was developed from another bacterial defense system.

In canonical DNA replication, the rules of base pairing reign supreme: Polymerases assemble their complementary DNA strand by matching adenine with thymine and guanine with cytosine on the template. Replication can also proceed with RNA as the template, thanks to polymerases called reverse transcriptases that use that nucleic acid to guide the fabrication of single-stranded DNA.

The new finding centers on DRT3, a defense system that protects bacteria from viruses, known as phages, that infect them. DRT3, the researchers found, bypasses the logic of base pairing. It relies on two reverse transcriptases: a conventional one that builds single-stranded DNA from an RNA template, and a second, unusual one that assembles its complement from its own built-in template. This unusual enzyme, called Drt3b, has amino acids in its active site that mimic a template RNA strand.

“The protein itself serves as the blueprint for the DNA sequence,” says Stanford biochemist Alex Gao, senior author on the study. “That was quite a surprise,” he says. “This is a fundamentally new way that life produces DNA.”

DRT3 appears to be widespread across bacteria, suggesting it is not a biochemical curiosity. Yet how it thwarts phages is still a mystery.

One possibility, Gao says, is that DNA helices made by this unique replication method act as molecular sponges that glom onto phage components, either directly hindering the phage or enabling other bacterial immune elements to recognize the infection. If that idea holds up, Kranzusch says, DRT3 would complement recent discoveries of polymeraselike proteins in other bacterial defense systems that produce nucleic acid polymers to detect and inhibit phage infection.

DRT3 also represents another mind-bending role for reverse transcriptases, long associated with retroviruses such as HIV, which uses one to synthesize a DNA copy of its RNA genome and slip into a cell’s chromosomes. In recent years, these enzymes have been revealed to be key players in some CRISPR bacterial defense systems and in the generation of entirely new bacterial genes. RTs are now appreciated as “highly adaptable scaffolds that have been repeatedly co-opted” for functions beyond DNA replication, Gao says.

Like CRISPR, DRT3 could have practical applications. “DRT3 represents an ‘all-in-one’ molecular machine for sequence-specific DNA synthesis, which is a rare find in nature,” Gao says. Drt3b churns out a specific DNA sequence. If scientists could figure out how to engineer it to produce other sequences, he says, they might make customized DNA strands, for instance to create advanced biomaterials such as DNA hydrogels.

More broadly, the discovery underscores how much remains hidden in microbial biology. DRT3, Gao says, should be viewed as “a catalyst to re-examine the dark matter of the microbial world.” And with numerous bacterial defense systems still uncharacterized, adds Aude Bernheim, a microbiologist at the Pasteur Institute, “it’s fantastic to imagine that many of these encode exotic biochemical functions like the one uncovered here.”

Helsinki— One morning in November 2025 here on the outskirts of Finland’s capital, David Gunnarsson slips off his winter coat and steps into a factory where the coldest temperatures in the universe are forged. Gunnarsson is the principal scientist for Bluefors, the world’s leading manufacturer of dilution refrigerators—researchers’ portal into the quantum world.

All around him, dozens of machines, draped with pipes and wires like golden chandeliers, shuttle between workstations on an overhead conveyer belt. Inside each device, liquid helium chills stacks of copper plates to ever-colder temperatures. At the bottom, a gold-plated finger will freeze a tiny electronic chip to just a hair above absolute zero (0 K, or –273.15°C). “The magic happens there,” Gunnarsson says.

Quantum technologies—from detectors that map the faint afterglow of the Big Bang to microscopes that image atoms—flourish at those temperatures, where thermal motion nearly vanishes. But the biggest booming application is quantum computers—the futuristic devices that may be able to solve problems traditional computers can’t. Tech giants such as Google, Microsoft, and IBM are pouring billions of dollars into quantum computers—and each of them demands fridges like the ones built at Bluefors.

As quantum computers get bigger, so, too, must the fridges. In a room at the factory, Gunnarsson shows off Bluefors’s next-generation fridge, a towering device the size of an elevator car. Called Kide, after the Finnish word for snowflake, it’s designed for today’s largest quantum computers, which can contain more than 1000 qubits—the quantum equivalent of transistors.

Around the corner, Gunnarsson opens a closet hiding a stack of scuba tanks filled with the fridges’ precious fuel: helium-3, a rare isotope of the gas that fills birthday balloons. This exotic ingredient is both the technology’s secret sauce and its Achilles’ heel. Helium-3 is primarily sourced from the decaying components of nuclear weapons, making it one of the most expensive substances on the planet.

Its scarcity could prove a serious bottleneck for emerging quantum technologies. Some researchers are keen to head off a supply crunch by developing new helium-3 sources—perhaps even mining it on the Moon. But others are trying to sidestep the problem entirely by reinventing how ultracold temperatures are reached. In Germany, one company is resurrecting a century-old magnetic cooling technique. And at Aalto University, a 30-minute train ride away from Bluefors, two groups are pursuing rival ideas for integrating coolers into the chips themselves. They aim to chill with superconducting traps for hot electrons or lights that radiate heat away—dispensing with the giant chandeliers and elaborate plumbing.

A full-blown helium-3 crisis is unlikely in the next decade. But some quantum researchers say they are already feeling the pinch of rising prices. “So many people can’t afford this kind of science any longer, and that’s so sad,” says Silke Bühler-Paschen, a physicist at the Vienna University of Technology. “One has to come up with alternatives that make all this feasible again.”

In 1951 , at a conference at the University of Oxford, German physicist Heinz London set all of modern cryogenic cooling in motion with a casual suggestion. Liquid helium was already a common refrigerant at the time, good for reaching temperatures of about 4 K, its boiling point. But London suggested the cooling could be boosted by mixing normal helium (helium-4) with helium-3, an isotope with one less neutron. The idea was laughed off as fantastical. Colleagues questioned where London planned to source the gas. Helium itself, with an abundance of just 5 parts per million in Earth’s atmosphere, is already a precious commodity. Helium-3, which constitutes 0.0001% of that helium, is extraordinarily rare.

But sure enough, a few years later, an unlikely source of helium-3 appeared. In 1955, at the height of the Cold War, the U.S. government began to develop hydrogen bombs, thermonuclear weapons whose destructive power is juiced by a dollop of tritium. With a half-life of 12.5 years, tritium happens to decay slowly into helium-3, which can be captured and sold. A decade later, a group in the Netherlands completed the first modern-day dilution refrigerator, capable of reaching temperatures as low as 0.22 K.

In principle, the cooling process London proposed works the same as sweating or dropping an ice cube in a drink. In both cases, water absorbs heat from its surroundings not by rising in temperature, but by going through a phase transition—from a liquid to a gas in the case of sweat, or from a solid to a liquid for the ice cube.

Similarly, a mixture of helium-3 and helium-4 absorbs heat during a special kind of phase transition. Below a temperature of roughly 1 K, the mixture naturally separates, like oil and water, into two layers: concentrated helium-3 sitting on top of a dilute mixture of the two species. If some helium-3 atoms are pumped out of the dilute layer, replacements will diffuse down from the concentrated layer. Like evaporation, this phase change draws heat from the environment. The helium-3 that’s pumped away can be captured and recycled back into the concentrated pool, allowing the cooling process to continue indefinitely—theoretically all the way down to a few millikelvins, thousandths of a degree above absolute zero. In practice, dilution fridges today operate below 20 millikelvins—hundreds of times colder than interstellar space.

Just as dilution fridges entered the scene, Finnish physicist Olli Lounasmaa, sensing the potential to corner a research market, established the Low Temperature Laboratory at what would later become Aalto University. Lounasmaa drew public attention—and funding—by regularly breaking his own world-record coldest temperatures, cementing Helsinki as a global hot spot for low-temperature physics.

Despite their success, the early dilution fridges were laborious to operate. They featured two main stages. First, a regularly replenished cold bath of pure helium-4 cools to 4 K as it boils off. Then, helium-3 is introduced and compressed, bringing the mixture down to the critical temperature where the separation occurs and kicks off further cooling.

By 2005, Rob Blaauwgeers, then a postdoctoral researcher at the Low Temperature Laboratory, had grown tired of coming in on weekends to refill helium tanks. He teamed up with his college friend Pieter Vorselman to streamline the first stage of the process by using a sequence of closed pipes to capture and recycle the helium-4 as it boils off. After constructing a prototype—which is still in operation, connected to a beer keg of helium-3—they went into business. In 2008, Blaauwgeers and Vorselman founded Bluefors—a combination of their last names. The private company has sold more than 1700 fridges to date and in 2024 grossed more than $200 million.

The helium-3 that dilution fridges rely on comes mainly from the U.S. government. The Department of Energy (DOE) collects the isotope when servicing aging tritium reservoirs in the U.S. nuclear stockpile and sells it off to companies, which in turn distribute it to researchers and manufacturers. Supplies are subject to geopolitical drama. After the 9/11 terrorist attacks, for instance, the demand for helium-3 in weapons detection systems made the gas nearly impossible to buy for research , prompting intervention from Congress.

Paschen experienced those vagaries starting in 2008, when she ordered a new dilution fridge filled with 180 liters of helium-3. By the time the fridge was ready for delivery, the price of helium-3 had risen from about $100 per liter to $3000. Today, 1 liter of the gas—less than a teaspoon of liquid—runs for anywhere from $1000 to $20,000, depending on subsidies and discounts. Up to one-quarter of the total price of a dilution fridge—which can cost more than $600,000—can come from “the little droplet of helium-3 you have in there,” says Paschen, who uses her fridge to study phase transitions in exotic materials . “You cannot buy a perfume that’s so expensive, or even a diamond.”

A 2021 DOE document suggests the U.S. stockpile is roughly 90,000 liters, up from 50,000 liters during the crisis in 2010. “We’re in a better spot,” says Christopher Landers, director of DOE’s Isotope Program. But his team is bracing for a looming surge in demand from quantum computing. “If that demand hits, this is serious.”

The largest quantum processors today feature hundreds or thousands of qubits. A practically useful device may require millions. Cooling such a large quantum chip—along with all the wiring to control it—would require a dilution fridge even bigger and more powerful than Kide. With current technology, a single machine that size might require tens of thousands of liters of helium-3, Gunnarsson estimates—a sizable chunk of the estimated U.S. stockpile. The U.S. government is taking heed. In January, the Defense Advanced Research Projects Agency put out a request for cryocooling proposals that require no helium-3, citing “dramatic transformative potential in both defense and commercial domains.”

The Bluefors team remains sanguine about long-term helium-3 supplies. “Helium-3 is mainly a byproduct of nuclear weapons—if you see the world today, it’s not really going away,” Vorselman says. Gunnarsson believes growing demand will induce nations and companies to find new sources. In 2021, an energy company in Canada began to extract helium-3 from the tritium that collects in special heavy-water nuclear power plants, offering the first nonmilitary source of the gas . Meanwhile, some fusion companies want to use helium-3 as a fuel, and they say their reactors will be able to breed more than they need. “If we need more helium-3, it’s going to be produced,” Gunnarsson says.

But the company is hedging its bets, exploring ways to optimize its fridges to consume less helium-3. It’s also looking into a literal moonshot. The Moon’s surface could be rich in helium-3 delivered by the solar wind, which isn’t deflected by a magnetic field as on Earth. Last year, Bluefors struck a $300 million prospective deal with Interlune, a U.S. company, to extract it. (If this sounds like the plot of a bad sci-fi movie, that’s because it was .) The company plans to launch its first exploration mission around 2027, and has promised to deliver 10,000 liters annually to Bluefors over the following decade . “I don’t know how far they’ll come, but it’s worth a chance,” Vorselman says.

But other researchers say a radical shift is needed. “If quantum is becoming a major industry, I really don’t see how it could be built on the basis of dilution cooling,” says Alexander Regnat, founding CEO of kiutra, a German cryogenics company.

In graduate school at the Technical University of Munich, Regnat was determined to overthrow the dilution refrigerator. He set his sights on magnetic cooling, a technique that had been around since the 1930s but had fallen out of fashion. It relies on the magnetocaloric effect, which causes certain materials to heat up when placed in a magnetic field that aligns their atoms’ magnetic spins. If you dump the heat and turn off the field, the atomic spins revert to their natural disorder, drawing heat from the environment and cooling anything in the vicinity.

Historically, the problem with magnetic cooling was that it only delivered a single pulse of cooling. Once the magnet was removed, there was no way to keep a sample from warming again. But Regnat and colleagues have developed ways to attach a sample to two magnetic fridges simultaneously, allowing one to recharge while the other cools. In addition to enabling indefinite cooling, this trick also means the magnetic fields can be about 100 times weaker, and less likely to interfere with sensitive quantum devices.

Anasua Chatterjee, a physicist at the Delft University of Technology, bought one of kiutra’s machines with a grant from the beer company Carlsberg. It’s not cold enough to operate a full-stack quantum computer, but it’s good enough to perform quality control tests on the quantum chips her lab fabricates. And it doesn’t involve helium-3—or worries about expensive accidental releases. “It can more or less do everything that the dilution fridge can do,” Chatterjee says. “It’s a bit more idiot-proof.”

Regnat says there’s still room for improvement. In March, kiutra unveiled an modular design that stacks together multiple magnetic fridges, to compound the cooling power they can deliver to a single device. By the end of the year, the company aims to release a fridge that can reach 20 millikelvins, with enough cooling power to put it on par with Bluefors machines. “I’m very confident this will be available as a real alternative and even outperform dilution refrigerators in the future,” Regnat says. “We’re getting there.”

At a café on the Aalto campus, Mika Prunnila blows on his fresh cup of coffee, the steam condensing on his sleek rectangular glasses. He belongs to a small cohort of researchers looking to cool quantum chips from the inside, instead of sticking them in a bulky refrigerator. For quantum computing, what really matters is not the ambient temperature of the room, but the heat, or average energy, of the electrons racing through the chip and its wires. Shoo away the fast, hot electrons—like blowing steam off a cup of coffee—and you’ve got a cold chip.

His technique traces back to a 1990s proposal to cool a metal by siphoning off the most energetic electrons into a superconducting trap. It relies on a junction between the metal and a superconductor, separated by a thin insulating barrier. Because superconductors have a gap in the energy states that electrons can occupy, they act as filters: Only the hottest electrons can tunnel across the barrier to an available state, carrying heat away.

Aalto physicist Jukka Pekola realized he could strengthen the effect by adding a superconducting junction to the other side of the metal and reversing the filter, so only the coldest electrons in that superconductor tunnel into the metal. The trick effectively doubled the cooling power.

In 1994, Pekola constructed the first double-junction sandwich out of copper and superconducting aluminum. Short on copper, he ran to a mechanics shop with a hack saw, cut off a piece of copper pipe, and brought it back to the lab, where he vaporized the metal and deposited it on his sandwich. “Things have changed a lot since then,” Pekola quips. To his surprise, the makeshift apparatus worked: It cooled electrons on the chip from 300 millikelvins to 100 millikelvins . Over the following decades, Pekola drafted a road map for microscopic, on-chip refrigerators and handed the project off to Prunnila at VTT Technical Research Centre of Finland, a state-owned research institute that shares an office building with Aalto. “I’m very happy that some of the things that we do seem to be some small seed for something practical,” Pekola says.

Magnetic cooling

Certain materials heat up when a magnet aligns their atomic spins. After that heat is dumped and the magnet is removed, the natural disordering of the spins can draw heat from a quantum chip.

Photonic cooling

If a light-emitting diode (LED) is powered with less electricity than it needs, the electrons inside it will steal heat from the atomic lattice to change energy levels and glow, drawing heat from a quantum chip.

Electronic cooling

Hot electrons jump over a barrier to high-energy states in a superconductor, leaving a cool chip. The same barrier also prevents vibrations in the material from warming the chip.

At VTT, Prunnila has been fighting another source of heat in a quantum chip: noisy vibrations in the crystal lattice called phonons. In 2020, his team managed to tame these vibrations using a specialized junction that allows hot electrons to escape from silicon while protecting it from phonons in the superconducting traps. They used this trick to cool an entire silicon chip by about 40%, from 244 millikelvins to 161 millikelvins.

In 2024, they showed the method also works at a higher temperature stage, where phonons are stronger and harder to block, cooling a chip from 2.4 K to 1.6 K using junctions made of niobium. They plan to stack chips and junctions on top of one another, building multiple cooling stages like a miniature dilution fridge. Simulations by his team suggest a cascading cooler should be able to get their chips from a few kelvins—where helium-4 can still reach—to tens of millikelvins, where many quantum computers must operate. “We now have all the pieces of the puzzle,” Prunnila says.

Prunnila sees on-chip cooling as a natural alternative to giant cooling systems that he says will become impractically cumbersome and expensive as quantum tech develops. Doing the majority of cooling on-chip would allow the entire apparatus—including the helium-4 precooling stage—to be shrunk to a fridge the size of a suitcase. “The whole field has been stuck on a track that didn’t lead to scalability,” he says. Paschen is intrigued and cautiously optimistic. “It’s just electrons moving around—it’s really elegant,” she says. “It would be a shame if it doesn’t come to a really big market application.”

Down the street at Aalto, Jani Oksanen has an even brighter idea for integrating refrigerators into chips. It grew out of frustration with his home movie projector, an old model that relied on hot, short-lived incandescent halogen lamps. He looked into projectors powered by light-emitting diodes (LEDs), which efficiently convert electricity to light. He never got around to upgrading his projector. But he did develop a fascination for LEDs.

LEDs work by applying an electric current to a special semiconductor, which forces electrons to fall to lower energy levels. As they relax, they give off their surplus energy as light. Normally, LEDs warm up, because some of the supplied electrical energy becomes heat. But if the voltage is a little lower than the electrons need to switch energy levels, the light can still glow. That’s because a fraction of the electrons will steal heat from the atomic lattice to make the jump—and the photons they produce will radiate the heat away. Starve the LED, and it starts to eat its own heat. “LEDs are not just simple electricity-to-light converters,” Oksanen says. “They are actually heat pumps.”

Physicists still haven’t managed a direct observation of this photonic cooling, mainly because the radiated heat is often deposited very close to the device, making the temperature drop difficult to detect. But in 2019, Oksanen’s group managed to show LED power conversion efficiencies exceeding 100%, which they took as indirect evidence of photonic cooling . In theory, you could also capture the light emitted by the LED with a solar cell and recycle that energy to help power the LED—allowing for massively efficient cooling, he says.

The technique may work best at higher temperatures, where there’s more energy to draw from a material. But his team is also exploring whether LEDs can cool efficiently at very low temperatures, as some have predicted. Meanwhile, other groups are pursuing a related cooling method that involves shining lasers at materials that re-emit the light at higher energies by drawing heat from the lattice. Such techniques could also find applications beyond quantum chips, cooling buildings as well as infrared cameras and electron microscopes .

Oksanen isn’t yet convinced LED cooling is practical for quantum cryogenics. “I don’t know that it’s possible,” he says. “But the people saying that it’s not possible, they don’t know that either.”

Over a customary Finnish dinner of reindeer and salmon soup, Gunnarsson, Prunnila, and Oksanen meet to plot out the future of cryogenic cooling. Although they are pursuing different paths toward absolute zero, they see each other as allies more than competitors. That’s in part because they all belong to the same lineage of researchers that hail from Lounasmaa’s laboratory and his “low-temp mafia,” as Oksanen calls it.

It’s also because none of them expects the dilution fridge to disappear any time soon. Its rivals, despite progress, still lack the power to get bulky samples cool enough. Yet Gunnarsson says it’s good for Bluefors to keep close tabs on the competition. The company’s objective is to cool by the most efficient means possible—even if that means one day shifting gears.

He imagines a future where hybrid cooling systems stack various platforms together at different temperature stages to “use the best technology where it is best,” he says. “If you draw on all the advantages these different technologies have, maybe you can also reduce the need for helium-3.”

Then they toast over shots of Jaloviina, a traditional Finnish brandy—which, like many things in life, is best served chilled.

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Since the landmark decoding of the human genome in the early 2000s, DNA sequencing has exploded. Traditional computers have struggled to keep pace with the deluge of data and soaring processing demands, creating a bottleneck in scientists’ capacity to mine the myriad variations in DNA for biological insights—and a push for alternative solutions.

Now, one option, quantum computing, may be a step closer to helping. In an announcement last week , researchers say they have for the first time encoded a complete, albeit small, genome, that of the hepatitis D virus, into a quantum computer, proving in principle these weird machines could one day aid genomics research.

“It’s an essential step,” says Guglielmo Mazzola, a quantum algorithms researcher at the International School for Advanced Studies in Trieste, Italy, who was not involved in the work. “If you want to do genomic processing, you need to first put the data in.” However, he cautions that until quantum computers can handle larger genomes or actually perform analyses on these data, it’s hard to judge whether they’ll surpass other, state-of-the-art techniques. “It is still unknown if quantum computers can really bring a benefit to this.”

Unlike classical computers, which encode information in binary bits of 0 and 1, quantum computers rely on qubits, which can be set to 0, 1, or a “superposition” state of both 0 and 1 at the same time. In theory, those simultaneous states enable a quantum computer to tackle problems that would overwhelm a conventional computer, such as cracking cryptographic codes or simulating the behavior of molecules . The machines can, in principle, speed up some optimization problems by representing many possible answers as wavelike states across their qubits. As those states evolve, they interfere like ripples on a pond, making better solutions more likely and worse ones less so.

The approach may hold promise for studying the immense genetic variation found in humans and other organisms. Although geneticists have long relied on reference genomes represented by single linear sequences, they’re increasingly turning to “pangenomes,” which capture many possible DNA or RNA sequences within a species by branching into alternative versions. Pangenomes are seen as key to personalized medicine and understanding pathogen evolution, for example, but they’re computationally complex. Building and analyzing them involves figuring out paths through a vast tangled maze of possible sequence combinations—just the sort of task a quantum computer might excel at.

Quantum for Bio (Q4Bio) , a $50 million program funded by Wellcome Leap, a high-risk biomedical funder spun off from U.K. charity the Wellcome Trust, was meant to stimulate this and other health-related quantum computing applications. Twelve teams, each focusing on a different goal, endured what one researcher called a Hunger Games –type contest: racing to demonstrate quantum advantages in their field in return for prizes and progression to a subsequent funding round.

The projects faced an uphill battle. Today’s quantum computers are unstable, error-prone, and limited in the number of qubits. Even encoding data into quantum states is laborious. “Sometimes loading the data is as difficult as doing the whole computation,” wiping out the advantage of using a quantum computer in the first place, Mazzola says.

One of the six Q4Bio projects to reach the final round was the Quantum Pangenome project, led by Sergii Strelchuk, a computer scientist at the University of Oxford, and colleagues at the Wellcome Sanger Institute, which shares a funder with but operates independently from Wellcome Leap. Strelchuk’s team developed algorithms to compress DNA sequences and encode them into quantum states as efficiently as possible. The team initially planned to test its approach with the bacterium-infecting virus ΦX174, which in 1977 became the first organism to have its DNA fully sequenced. But ΦX174’s 5386 bases needed a quantum computer with 387 qubits—too many for the 156-qubit IBM processor the researchers used. So they turned to hepatitis D, a significant cause of liver disease and, at about 1700 bases of RNA, the human virus with the smallest known genome.

They were able to encode hepatitis D’s genetic information in 117 qubits—work they plan to describe in a preprint in coming weeks. They’re now deciding what to do with the encoded data, says collaborator James McCafferty, Wellcome Sanger’s chief information officer. “We’re at the start of the journey.” The researchers have already posted a preprint describing quantum algorithms that could be used to assemble pangenomic data. Strelchuk says the team wants to develop an online interface where researchers could one day upload, process, and analyze sequences.

Stefan Bekiranov, a computational biologist at the University of Virginia, praised the apparent technical accomplishment, but said he doesn’t see quantum genomics taking off any time soon. “You’re up against extremely powerful classical computing algorithms,” he says. “There’s a lot of hard work ahead.”

Strelchuk says he’s optimistic that honing methods for compressing and encoding genomic data, combined with bigger, more resilient quantum computers, will make the prospect more realistic in the coming years. Although applying quantum computers to the human genome, with its 3.1 billion base pairs, remains a distant ambition, researchers could initially focus on shorter, medically important and highly variable regions of our DNA, he adds.

Teams working on other health-related projects under Q4Bio echo this optimism. University of Chicago computer scientist Fred Chong, who leads a project on cancer biomarkers, developed hybrid quantum-classical algorithms to mine vast cancer sample data sets for patterns that could help predict disease. Although his project’s approach, described in another pending preprint, can’t yet outperform classical methods on quantum computers because of limited qubits, “we expect machines to get to this capability in the next 2 to 3 years.”

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After modern humans made it to Europe some 50,000 years ago, they hunted and gathered in small groups for scores of generations. Then, 10,000 years ago, people in Europe began to farm and settle down. About 5000 years later, cattle herders from the steppes of Eurasia surged into Europe with the wheel and metal tools and weapons, ending the Stone Age and ushering in the Bronze. Cultural and technological changes kept accelerating, from the rise of the first cities to the spread of empires to our modern age of trains, planes, cellphones, and artificial intelligence.

All that societal upheaval may have supercharged our biological evolution as well, according to a study of nearly 16,000 ancient human genomes published this week in Nature . Researchers leveraged the exponential growth of ancient DNA samples to measure human genetic change over 18,000 years and found hundreds of genetic shifts across Europe’s population in a relatively short time. “It’s a powerful new approach to detecting natural selection from ancient DNA,” says Iain Mathieson, an evolutionary geneticist at the University of Pennsylvania. For example, the analysis finds new signs that natural selection nudged traits such as tuberculosis resistance and lower body fat to become more common in western Eurasians during this time.

To look for evidence of evolution in humans, researchers compared the DNA of ancient people living in Europe and the Middle East—where paleogeneticists have concentrated their sampling—with each other and with modern-day individuals. Within the past 10,000 years, hundreds of particular versions of genes have become measurably more or less common, a sign of natural selection at work. “The genome is under massive selection pressure over the last 10,000 years,” says Harvard University geneticist Ali Akbari, a co-author on the study. “Everything has changed about the way we live, and that’s reflected in our genome and how it’s trying to catch up.”

Previous studies of human evolution, based largely on analyzing the DNA of modern people, had concluded our genomes were relatively stable over the past tens of thousands of years. That’s because modern populations such as Western Europeans, Africans, and East Asians show considerable genetic similarity, suggesting not much evolution has happened since people on those continents diverged.

But the best way to measure change over time is with ancient samples. The massive study draws on thousands of previously published ancient genomes, genetic data from about 6000 modern individuals, and—most important—the previously unpublished DNA of nearly 10,000 additional ancient people, most gathered recently by a group led by David Reich, a geneticist at Harvard. The team’s paper identifies these new genomes only by their age and regional location, but Reich says future papers will describe them more fully.

This data set is big enough to probe for population-level trends. “It’s a really important paper,” says Alexander Young, a statistical geneticist at the University of California, Los Angeles. “It shows the amount of ancient DNA data has reached the scale where we can powerfully interrogate selection over the last 10,000 years.” Reich, an ancient DNA pioneer, adds: “This is the most important work I have been involved in for a decade. … It is finally realizing the promise of ancient DNA to reveal as much about biology as history.”

His team’s analysis shows that beginning about 10,000 years ago, after the introduction of farming, 479 genetic variants became more or less common in the European gene pool, a sign of adaptation. “It makes sense to me that the advent of agriculture would have induced selection pressure for various things,” Young says. For example, variants connected to tuberculosis resistance became more common starting 6000 years ago, then decreased over the past 3000 years. Variants linked to higher body fat became less common, genes for red hair became more common about 4000 years ago, and those for male pattern baldness declined over the past 7000 years. “The genome is alive with signal,” Reich says. He sees “a period of unusually intense … and also fluctuating natural selection—variants shoot up in frequency, then down.”

Sometimes the environmental pressures behind the changes are obvious, says Lluis Quintana-Murci, a population geneticist at the Pasteur Institute. For example, genes connected to higher body mass became less common once farming emerged, perhaps because crop domestication reliably produced surplus calories. “I found it supercool they can show that,” he says.

Another suite of mutations, mostly associated with disease resistance and autoimmune conditions, spiked in frequency starting in the Bronze Age, about 5000 years ago. That’s when Europe’s population density started to rise exponentially and people began to live closer to each other and to domesticated animals. “The Bronze Age probably saw massive change in pathogenic exposure, leading to selection touching genes related to immunity and host-pathogen interactions,” Quintana-Murci says.

Better understanding of selection pressures could boost medical understanding of diseases that still plague us today. The team’s results confirm findings from another recent paper showing that genes that heighten multiple sclerosis risk became more common in the Bronze Age . With thousands more individuals in the data set, “we’re getting closer to being able to answer some of these selection pressure questions,” says Harvard statistical geneticist Alison Barton, a co-author of the paper.

In other cases, the selection pressures behind genetic shifts remain murky. Using published studies and a database that combines health, lifestyle, and genetic data from hundreds of thousands of modern people in the United Kingdom, the team found that clusters of genes associated with traits such as walking pace, as well as genes correlated with behavioral outcomes such as income and years of schooling, became more common over the past 5000 years.

But it’s not obvious how these clusters of genes gave prehistoric people an evolutionary boost. “This study represents almost a decade of intense work, but it’s really just scratching the surface,” says Harvard evolutionary biologist Annabel Perry, another co-author. “They didn’t have college in the Neolithic, so what is the trait that’s really changing? This is an invitation for researchers to do the digging to find those associations.”

Migration and mingling of populations can also trigger fluctuations in the frequency of various genes, so the researchers applied methods from medical genetics to rule out those causes. Not everyone agrees they succeeded. The researchers treat changes in genetic ancestry over time as evidence of selection—but whether those ancestry shifts reflect selection, and if so on which traits, is not resolvable using their approach, says Arbel Harpak, a population geneticist at the University of Texas at Austin. “The study is best viewed as offering amazing data and provocative hypotheses that will require much further scrutiny, rather than a settled account of adaptation in Eurasia,” he says.

Reich hopes future work will explore these questions in other parts of the world. Several recently posted 
preprints —including one by some of the authors of the Nature paper —suggest similar dynamics were at work in other populations. Other time periods might also have seen rapid evolutionary change, but haven’t been or can’t be sampled. “The most exciting time period might be between 1,800,000 and 300,000 years ago when hominin brains triple in size and modern humans appear,” he says. “We don’t have that data.”

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After gazing up at a patch of sky last night near Polaris, the North Star, astronomers completed the largest map of the universe ever created. Compiled over the past 5 years by the Dark Energy Spectroscopic Instrument (DESI), the map features a total of 47 million galaxies. That’s 13 million more galaxies than originally planned: a boon made possible by DESI’s ability to map galaxies across the northern sky at unprecedented speed.

DESI’s aim is to look for ripples in the distribution of galaxies at various distances from Earth, which tell astronomers how fast the universe was expanding at different times under the influence of an unknown force referred to as dark energy. Earlier data from DESI hinted that this force has varied in wholly unexpected ways , a sign that dark energy might not be a constant. As a result, researchers will be eagerly awaiting the analysis of this latest map. “There was a great deal of excitement” about DESI’s interim result last year, says cosmologist Bhuvnesh Jain of the University of Pennsylvania.

To pull off this mapping effort, DESI repurposed an existing telescope, the 4-meter Nicholas U. Mayall Telescope at Kitt Peak National Observatory in Arizona, and replaced its camera with an instrument that captures incoming light with the ends of 5000 optical fibers . As the telescope moves to each new area of sky, the fiber ends are moved to new positions by 5000 tiny robot arms so each fiber collects light from a single galaxy and feeds it to a spectrograph, which splits the light apart like a prism into its constituent wavelengths. The spectra allow researchers to calculate the distance to each galaxy and so to create a giant 3D map.

DESI co–project scientist David Schlegel of Lawrence Berkeley National Laboratory says they did more than expected through luck and continual improvements. “All of us know a lot more about robots and motors than we did 10 years ago,” he says. “The amount of downtime is very close to zero.”

DESI was designed to stress test the idea that dark energy imposed a steady acceleration, which could be accounted for with a “cosmological constant” added to Albert Einstein’s theory of gravity, general relativity. Instead, DESI’s 3-year results suggest the acceleration has waxed and waned through cosmic history. The statistical significance of the result is low so it could still disappear with the addition of more data, but theorists have been busy trying to fit this variability into a new framework. “It rules out our simplest physical pictures of dark energy and says that maybe we shouldn’t deploy Occam’s razor too prematurely,” Jain says.

Schlegel says it will likely take a year before the DESI team can determine what the new map says about dark energy. In the meantime, the instrument’s miniature army of fibers and robots is marching on to other parts of the sky where observing is harder—such as lower in the southern sky—in hopes of bagging more than 15 million more galaxies.

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Every fall, hundreds of thousands of birds soar through the skies above New Jersey’s Cape May Peninsula on the way to their wintering grounds. The vast majority migrate at night, and whereas some make their presence known with hoots, trills, and other calls, many others fly in silence. Now, scientists have found a way to spot these nighttime travelers with thermal imaging—the same technology used to find lost hikers. The technique, described in this month’s issue of Ornithology , quite literally shines a light on birds that would otherwise be invisible .

“We always knew that [these birds] migrated at night, but we could never see them,” says Felix Liechti, an ecologist who pioneered using small tracking devices to trace bird migration paths but wasn’t involved in the new work. Being able to directly observe night-flying migrants, he adds, could help reveal which species are most vulnerable to threats such as wind turbines and light pollution.

Migrating birds may fly by night because the air tends to be cooler and more stable between the hours of dusk and dawn, helping the animals conserve energy and avoid dehydration. The cover of darkness may also shield them from predators. These risks tend to be amplified when crossing physical features such as mountain ranges or bodies of water, says Gautam Apte, a field biologist at the Black Swamp Bird Observatory and co-author of the new study. Birds migrating near Cape May, for example, are reluctant to fly over Delaware Bay during the day, when they are more exposed, but have little trouble making the crossing after sundown.

Whatever the reason, these red-eye flights have long presented a challenge for ornithologists. In the late 1800s, they used telescopes to count the number of birds seen crossing the face of the Moon. Later on, weather surveillance radar provided a major advance, allowing scientists to study the movement of birds in the atmosphere over huge geographic ranges. This method, however, cannot distinguish species and often fails to capture birds flying close to the ground.

Scientists also rely on acoustic monitoring, but the approach can only identify birds that produce audible calls. The result is a bunch of “disconnected pieces,” says study co-author Andrew Farnsworth, a bird migration researcher at the Cornell Lab of Ornithology.

In the fall of 2019, field ornithologist and lead study author Thomas Johnson found a way to connect some of those pieces. Nocturnal migrants may be invisible to the naked eye, he reasoned, but their heat signatures can still be detected via thermal imaging optics that can visualize the infrared radiation emitted by objects and animals. Using one of these devices, which resemble handheld camcorders or compact telescopes, quick-fingered observers can locate a bird flying overhead, briefly illuminate it with a flashlight, and then snap a photograph with a regular camera.

Johnson, an experienced birder and photographer, found his method didn’t just work for large birds such as owls and herons, but could also be used to identify small migrating songbirds. The next year, he recruited several collaborators to deploy the imaging on a larger scale. For three autumns, a group of volunteers calling themselves the “night club” ventured out onto the dunes and beaches of Cape May, working in small teams to detect and photograph migrating birds.

“There’s a lot of hand-eye coordination involved,” Apte explains. One observer is responsible for scanning the night sky with a thermal imaging monocular. After identifying the heat signature of a bird, that same person uses a high-intensity flashlight to illuminate it, allowing a second observer to capture it with a digital camera. Because artificial light has the potential to confuse migrating birds, the team took care to use short bursts of light, quickly turning off the flashlight if a bird made an abrupt deviation from its flight plan.

Using this technique, the researchers documented thousands of nocturnally migrating birds, capturing many species that would have been missed with acoustic monitoring and yielding several surprises. The eastern kingbird, for example, is thought to mainly travel during the day, but the team regularly witnessed members of the species migrating at night. The researchers also photographed several common backyard birds—specifically northern cardinals, red-bellied woodpeckers, and downy woodpeckers—generally considered to be sedentary, year-round residents. Although these birds may simply have been opportunistically flying short distances in search of mates, food, and new territory, the vast majority were heading west—the expected direction for migratory birds during the fall season.

The new method is “an extraordinary achievement,” says ornithologist Sidney Gauthreaux, who helped pioneer the use of radar to study migration but wasn’t involved in the new study. The technique also seems “incredibly tedious,” he adds. “It just seemed remarkable that they were able to get the amount of data they got.”

Photographing night-flying birds certainly isn’t for the faint of heart, says study co-author Cameron Rutt, an ornithologist and conservation biologist at the Field Museum of Natural History. Members of the night club often sacrificed their sleep, waking up many hours before sunrise and staying out long after sunset. On one occasion in 2020, volunteers worked for 11 hours straight in the darkness.

It was all worth it to catch a glimpse of a previously invisible bird in flight, Rutt says. “It just feels like a magic trick,” he says. “You’re standing out there in complete darkness, and then voilà.”

The approach will likely be most effective when integrated with methods such as acoustic monitoring and radar, allowing researchers to collect many types of data on larger numbers of birds. The team hopes this work will grant scientists deeper insight into migration, which is the riskiest stage of a bird’s annual cycle, potentially illuminating blind spots in conservation plans for threatened species.

With the new study, the team also hopes to honor Johnson, who died suddenly in 2023. “It was important for all of us to see this project through, because Tom had invested so much time and energy into it and was so excited about this work,” Rutt says. “This was just a small thing we could do to help contribute to his legacy.”

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Each summer in California’s Central Valley, the land bakes as temperatures climb past an oppressive 35°C. And then, a wall of fog rolls in from the ocean, cooling the air and moistening the ground with tiny water droplets.

For millions living in the most populous U.S. state, the fog spawned where a cold ocean meets a Sun-warmed coast is like “natural air conditioning,” says Peter Weiss-Penzias, an atmospheric chemist at the University of California (UC), Santa Cruz. It also delivers critical water for agriculture and ecosystems. Yet scientists don’t know what makes some years foggier than others, how fog might change in a warming world, or what pollutants it carries. “Fog has more or less been this underdog,” says Sara Baguskas, a biogeographer at San Francisco State University who notes that funders have long viewed it as too regional for big investments. Compared with research on rain and drought, she says, fog “doesn’t stack up.”

That’s about to change. This month, Baguskas, Weiss-Penzias, and their colleagues will begin fieldwork on the $3.65 million Pacific Coastal Fog Research project , funded over 5 years by the Heising-Simons Foundation. Using fog collectors and climate models, the project will for the first time systematically measure coastal fog’s chemistry, ecological role, and response to warming. The campaign is a “hugely unique and unprecedented opportunity for us to connect the dots,” Baguskas says.

At its simplest, coastal fog is a kind of low-hanging cloud. Over the cold ocean, moist air cools into droplets around dust and airborne particles. As inland air warms and rises, it pulls the fog ashore. Unlike the vast decks of marine stratocumulus clouds—long a focus of climate research—coastal fog forms right at the surface and remains poorly represented in climate models.

Yet its impacts can be outsize. In California’s famous redwood forests, fog can provide 40% of the ecosystem’s summertime water. In the Salinas Valley, nicknamed the “salad bowl of the world,” fog nourishes the cropland that generates more than half of the United States’s lettuce and one-quarter of its strawberries. And in cities, fog can scavenge and carry off harmful pollutants such as nitric and sulfuric acids, soot, and trace metals.

Fog may also be endangered. In 2010, UC Berkeley forest scientist Todd Dawson and his then–graduate student James Johnstone looked at fog measurements over time at airport weather stations in California. They found that fog had declined by 33% since 1951 —raising worries that warming was already thinning it. In the 15 years since, the trend has continued, Dawson says, but the finding hasn’t been confirmed in other ways. Ground station data are scarce, and satellite images can’t distinguish fog from other low-lying clouds. “There are some big unknowns about fog out there that I think are definitely worth working on,” he says.

Climate models could clarify how warming will affect fog, but so far the predictions are “wishy washy,” says Harindra Joseph Fernando, an environmental fluid dynamicist at the University of Notre Dame. That’s because warming affects both the ocean and the land—and fog depends on the temperature contrast between the two. A warmer ocean could suppress fog by weakening the cooling that helps moist air condense into droplets. But a warmer land could strengthen the flows that usher fog inland. Climate models, which have long struggled with the physics of cloud formation , have a hard time testing the scenarios, Fernando says.

The Pacific fog project aims to do better. Travis O’Brien, an atmospheric scientist at Indiana University Bloomington, will use a variable resolution global climate model, never before applied to fog, which can zoom in on coastal regions without the computational cost of running at ultrahigh resolutions everywhere. He has already produced more than 100 years of simulations, setting the stage for modeling runs that will simulate a warmer future. He will also have the model replay the past, hoping to determine whether the fog declines Dawson found were because of natural variability or human-driven warming.

In addition to computer screens, the campaign will deploy mesh ones: fog collectors that face the wind and funnel fog into rain gauges. This month, Baguskas and Weiss-Penzias plan to erect them at the first of 15 field sites from San Diego to Mendocino, spanning urban, grassland, forest, wetland, and agricultural environments.

By measuring the volume and chemistry of the captured water, Baguskas hopes to learn how much moisture fog delivers to plants and soils—and whether the bounty will change over the 5 years of the project. Her observations should interest California’s wine industry, where changes to water inputs can alter the flavor profile of grapes.

Weiss-Penzias will study the pollutants that fog captures, having previously found evidence of methylmercury, a hazardous chemical that can damage the cardiovascular, reproductive, and immune systems. He will also examine fog’s microbial ecosystem, determining the concentrations and identities of fog’s living constituents—and whether they can reproduce. Weiss-Penzias plans to search for cyanobacteria, picked up in sprays from marine algal blooms, which could spread toxins inland. “Whatever we find, whether it’s presence or absence of something, is going to really plant a flag,” he says.

The new campaign is “hitting many of the highlights,” says Kathleen Weathers, a scientist at the Cary Institute of Ecosystem Studies. But Dawson says that with only 5 years to study such an interconnected system, “I have my doubts that they’re going to make a heck of a lot of headway” on understanding fog’s ecological importance.

The Pacific Coastal Fog Research team hopes the work will inspire a global research push, not least because coastal fog occurs along the hot western coasts of other nations, such as Peru, South Africa, and Namibia. They plan to partner with scientists in Chile, who are exploring collecting fog for drinking water in the parched Atacama desert. And the team plans to publish its data and stoke collaborations through an online “virtual fog institute.”

Even though one campaign can’t close the chapter on fog, “There’s so little research that really looks at the connection between the ocean, atmosphere, [and] terrestrial system,” Weathers says—and this project will hit all three. “It’s been a very long time coming.”

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Ants will strike up partnerships with other kinds of insects— guarding aphids in exchange for food , for example—but they are almost always aggressive toward other ants. So, it was a surprise to entomologist Mark Moffett when he observed two ant species getting along quite nicely, with the smaller one apparently cleaning the much larger one, possibly removing and snacking on harmful bacteria or tiny parasites. In a paper published this week in Ecology and Evolution , Moffett proposes that the unusual behavior is the first example of cleaning mutualism in ants , where two species benefit from their relationship with each other.

“It certainly looks like a mutualism,” says Joe Parker, an evolutionary biologist at the California Institute of Technology who was not involved with the work. “The payoff must be pretty substantial for this interaction to evolve.”

Cleaning behavior is well known in nature. Small fish will swim among larger predators, which permit them to pick parasites off their bodies to eat. Birds called oxpeckers do the same with rhinoceroses. Even when the larger animal might be able to kill and consume the smaller one, they get a greater benefit by having their parasites removed. The smaller animal gets a free meal in the process.

Moffett, who is based at the Smithsonian Institution’s National Museum of Natural History, noticed the ant behavior while visiting a research station in the Arizona mountains in 2006. He was watching red harvester ants ( Pogonomyrmex barbatus ), which are known for their large, deep nests. That morning the workers were milling about on the ground outside their nest when a few stationary ants caught his attention. Clambering on them were as many as five ants belonging to the genus Dorymyrmex , just one-third of the size of the 7-millimeter-long harvester ants. The smaller ants walked on and around the larger ants, typically for a minute or so, and seemed to be licking them.

Over the next 5 days, Moffett saw and photographed multiple instances of this behavior at different nests. Sometimes, a harvester ant would walk right up to the entrance of a Dorymyrmex nest and wait for them to climb on. With harvester jaws spread wide, the small ants would nibble in between them.

Ants will occasionally try to steal food from another species, but the harvester ants weren’t carrying anything to eat. What were they doing? Moffett thinks the Dorymyrmex ants could be removing bacterial films or tiny parasites, not visible to the naked eye or hiding in places the harvester ants can’t reach themselves. Another idea is that the ants might be exchanging surface microbes that are important for health.

P. barbatus is a well-studied species of the U.S. Southwest, yet no one had reported this interaction before. “Undiscovered fascinating behaviors are still all around us, waiting for a careful observer to note them,” says Neil Tsutsui, an evolutionary biologist at the University of California, Berkeley not involved with the study. “If you see a creature doing something interesting or weird, take lots of good pictures!”

A breakthrough drug that can prevent HIV infection for 6 months with one injection is set to become available to 3 million people in cash-strapped countries over the next 3 years, an increase of 50% from previous commitments.

The U.S. Department of State and the Global Fund to Fight AIDS, Tuberculosis, and Malaria jointly announced today they plan to rapidly scale up the use of the Gilead Sciences drug lenacapavir in people at risk of becoming infected with HIV, a prevention strategy known as pre-exposure prophylaxis (PrEP). They will also expand the number of countries eligible to receive the drug.

“Back in November 2024, we thought 2 million was a good starting point number, but the experience we’ve had so far suggests that actually, if we really want to make the most of this, we have to go bigger, and we have to go bigger faster,” Global Fund Executive Director Peter Sands said this morning at a lenacapavir panel discussion organized by the Center for Strategic and International Studies (CSIS).

Lenacapavir PrEP, which provided nearly 100% protection from HIV in clinical trials, was deemed Science ’s Breakthrough of the Year in 2024 and soon after received the green light by regulators around the world, including the U.S. Food and Drug Administration in June 2025. Even before these approvals, Gilead announced it would allow six generic manufacturers to produce the drug for 120 low-income countries. It also agreed to sell lenacapavir at zero profit to the Global Fund, an international financing body set up in 2002, until those companies could ramp up production.

To date, the Global Fund has delivered enough lenacapavir PrEP for 135,000 people in nine countries, all of them in Africa, six of which have started to administer it, according to Sands. The fund plans to start to provide support to 15 additional countries by the end of this year, including Thailand, Indonesia, Honduras, Georgia, the Philippines, and Ukraine. “There’s always a tension whenever you roll out something quite as game changing as lenacapavir between sort of giving everybody a little bit and concentrating it,” Sands said. “And we take the deliberate decision to focus on the places where it can have the most impact.”

HIV activists have sharply criticized Gilead for excluding many middle-income countries from purchasing the generic product, including Brazil, which participated in the clinical trials that led to its approval. And Doctors Without Borders has complained that Gilead has refused to sell the drug for use in its medical operations, many of them in humanitarian emergencies. The moderator of today’s panel, CSIS’s Katherine Bliss, also noted there have been “concerns expressed” that the partnership between the U.S. government and the Global Fund has placed an emphasis on preventing HIV transmission to pregnant and breastfeeding people—who can infect their babies—with no mention of other high-risk groups, such as men who have sex with men and people who inject drugs.

Sands said he expects generic manufacturers to start to deliver lenacapavir by the middle of 2027. Gilead hopes the initial rollout with the Global Fund will boost worldwide demand, the company’s CEO, Daniel O’Day, said today at the panel. “We know that the way that we get to hundreds of countries and tens of millions of people is through a sustainable, high-volume generic supply,” he said.

Oral PrEP, which requires taking a daily pill, came to market in 2012, but many people find it difficult to take, in part because of the stigma associated with having anti-HIV medication at home. Receiving a shot twice a year provides a more discreet and simpler option, and it could be the less expensive strategy in the long run. “We’re looking at a horizon where, once the generics are fully online, lenacapavir will be more cost effective than oral PrEP potentially, which is tremendous,” said Jeremy Lewin, a senior State Department official who also spoke on the CSIS panel.

New HIV infections have dropped by 40% globally since 2010, largely because HIV drugs can lower viral levels in people living with the virus so effectively that they can no longer transmit it. But the most current data available show that an estimated 1.3 million people became infected with HIV in 2024, about the same number as in the preceding 2 years. “If we can get that 1.3 million number dramatically down, that changes the nature of the AIDS epidemic, and we can really start thinking about the end of AIDS,” Sands said. “And I think that’s in our grasp.”

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The U.S. National Science Foundation (NSF) has chosen a record number of students this year to receive its prestigious graduate fellowship, rebounding from last year’s unusually small cohort. The size of this year’s class, announced today , together with a more traditional distribution across fields, could ease fears that NSF, under pressure from President Donald Trump’s administration, had decided to shrink and alter the nature of a program that has supported 50 future Nobel laureates since it began in 1952.

“My take is that the STEM community’s activism around last year’s cuts appears to have had significant positive impacts on this year’s class,” says Susan Brennan, a cognitive psychologist at Stony Brook University and former fellowship program officer.

The 2599 fellows in this year’s class surpass the previous record of 2554 in the 2023 cohort and is 42% larger than last year’s unusually small class of 1500. The 2025 class was announced in two stages, and the second cohort of 500 was dominated by artificial intelligence and quantum information science , top priorities for the White House.

This year’s class returns to a more familiar distribution, with engineering and biology once again leading the pack. But whereas in 2023 and ’24 those two disciplines each garnered about one-quarter of the awards, this year saw a shift toward engineering, with some 35% of the awards going to students in that area, followed by 19% in biology. At the same time, the life sciences was the discipline most represented among the honorable mentions, comprising 40% of the 1440 total. Among awardees, computing and information science saw a slight uptick, from 7% in 2023 and ’24 to 10%. And psychology took a hit, from 5% and 6% to 2% of the overall pie.

The NSF fellowship provides students with an annual stipend of $37,000 for 3 years and gives their institutions $16,000 annually to defray tuition and other educational costs. It’s also a portable scholarship, in contrast to the typical arrangement in which a graduate student’s support is tied to their institution, either from their adviser’s research grant or a graduate training program in a particular field. NSF says it received nearly 14,000 applications for this year’s class.

NSF has launched an initiative to identify high-tech companies willing to contribute to the support of future classes of graduate fellows. But an agency spokesperson says, “NSF plans to support [this year’s] fellows with available appropriated funds in [fiscal year] 2026.”

In keeping with President Donald Trump’s priority of developing fusion energy, the Department of Energy’s (DOE’s) tech development wing will significantly boost its investment in fusion research. The Advanced Research Projects Agency-Energy (ARPA-E) will provide $135 million in funding for cutting-edge fusion research over the next 18 months , the agency announced on 8 April. That equals the amount ARPA-E spent on fusion over the past 12 years.

Those earlier investments helped launch several startup companies that are developing novel fusion reactor concepts, notes Conner Prochaska, director of ARPA-E. And they have triggered $1.5 billion in private investment, he says. “We want to double down on that,” Prochaska says. “If past is prologue, we think this will result in some very positive movements for the overall fusion industry.”

Fusion scientists seek to harness the basic nuclear physics that powers the Sun. For decades, they have strived to make nuclei of two heavy isotopes of hydrogen, deuterium and tritium, merge and fuse to make helium and highly energetic neutrons. To make that happen, they need to heat an ionized plasma of deuterium and tritium to temperatures of hundreds of millions of degrees.

Scientists have taken two main approaches to producing such a plasma. In magnetic confinement fusion, the plasma is contained by the magnetic field within a doughnut-shaped device called a tokamak . In inertial confinement fusion, the plasma exists for just a split second within a tiny capsule imploded by blasting it with high-power lasers. For decades, DOE has invested heavily in both approaches, and in December 2022, researchers at DOE’s National Ignition Facility, an inertial confinement experiment at Lawrence Livermore National Laboratory, announced they had achieved an implosion that produced more energy than was pumped into the capsule by the lasers —although far less than was consumed by the whole facility.

ARPA-E’s previous funding has been crucial in encouraging researchers and startup companies to explore other concepts, says Farhat Beg, a physicist at the University of California San Diego who works on inertial confinement. “There was not much going on in alternate fusion schemes, and with ARPA-E funding, that landscape changed,” Beg says. “That was a huge impact.”

One of those alternative schemes has been developed by Cary Forest, a plasma physicist at the University of Wisconsin–Madison. Forest and colleagues replaced the doughnut-shaped tokamak with a pair of flat high-field coils 2 meters apart that face each other like mirrors. The nuclei in the plasma bounce back and forth between the coils, swirling along magnetic field lines just as electrons trapped in Earth’s magnetic field bounce from pole to pole to create the aurorae. ARPA-E provided $10 million to produce a prototype device, and Forest and others have spun out a company called Realta Fusion to scale it up and produce power.

DOE’s own magnetic and inertial confinement programs have been far more expensive, and have sometimes faced setbacks—for example, the cancellation in 2008 of a $170 million experiment that was behind schedule and overbudget . As a result, the programs have become cautious and conservative, Forest says. In those programs, “It’s more important that you not fail than you be successful,” he says. “The thing that ARPA-E allows for is risk.”

Forbidden from reproducing other DOE efforts, ARPA-E instead targets novel, higher risk ideas, Prochaska notes. With the new funding, he says, ARPA-E will back work on lower cost systems for heating the plasma, alternative fuels, and systems for extracting the energy from the neutrons and converting it to electricity.

Can ARPA-E’s new spending spree catalyze an additional $1.5 billion in investment? Sure, Beg says. “I have no doubt that kind of capital could be raised.”

Forest, however, is less confident. “There isn’t an infinite number of good ideas,” he says. “We have to be supercareful that it’s not more important to just get the money out the door than it is to fund something that will be feasible.”

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Along the coast of Argentine Patagonia, Magellanic penguins ( Spheniscus magellanicus ) spend their days shuffling across pebble beaches, plunging into the Atlantic Ocean for anchovies and sardines, and returning to the noisy colonies they call home. But a few dozen of these seabirds have also become marine detectives, sporting a soft silicone band on their ankle that absorbs traces of “forever chemicals”—toxic industrial compounds that can hang around for decades, harming both humans and wildlife.

Already, these unwitting toxicologists are showing promise in tracking forever chemicals, known as per- and polyfluoroalkyl substances (PFAS). The compounds—used in products ranging from waterproof clothing to food packaging—are resistant to heat, water, and degradation. They persist in the environment for decades and travel long distances by air and sea, posing risks to Patagonia’s coastal species. In a pilot study published last month in Earth: Environmental Sustainability , 91% of the Magellanic penguins’ bands detected at least one industrial pollutant where the birds swam and nested .

The new study is a first step toward understanding this persistent but underexplored ecological problem, says biologist Esteban Frere at the National University of Austral Patagonia, who was not involved with the work. “There are very few studies on the presence of PFAS in Patagonia,” he says, “and we know even less about their negative effects on penguin health.”

“We have no better way of understanding the ocean [these animals] live in than letting them tell us the story themselves,” says study co-author Marcela Uhart, a veterinarian at the University of California, Davis. The penguins, she says, “are now our elite team of marine detectives.”

To detect environmental hazards early, scientists use “sentinel” animals whose health, behavior, and chemical exposure act as biological warning systems. Until now, only a handful of species, including dogs, eagles, and horses, have been used to monitor PFAS.

Uhart’s team turned to penguins because they regularly move through remote marine environments that are difficult for humans to sample. They’re also particularly vulnerable to PFAS exposure because the contaminants tend to accumulate in animal tissue. As top marine predators, the birds eat several species of fish that are themselves enriched in pollutants, causing the toxic compounds to rapidly build up in their tissues.

But monitoring PFAS in penguins has traditionally required drawing blood, pulling feathers, or collecting samples of guano from remote breeding colonies. Besides being stressful for the animals, “a blood sample only tells you what the penguin ate and metabolized, not what it comes into contact with in its environment,” Uhart says.

Seeking both better samples and a more humane detection method, Uhart’s team fitted penguins with soft silicone bands loosely placed around one of their ankles. Silicone acts as a passive sampler that absorbs chemicals present in the surrounding environment, allowing the bands to record the contaminants penguins encounter in their daily lives. Similar bands have already been used in experiments with firefighters to detect chemicals they are exposed to during fires. “It’s a useful, accessible, and inexpensive technology that was already within reach,” Uhart says.

The team placed the bands on 55 penguins in two colonies along the Patagonian coast of Argentina during three breeding seasons between 2022 and ’24. The devices remained on the birds for between 2 and 9 days before the team retrieved them and analyzed them in the laboratory. The researchers screened the bands for 40 different PFAS compounds.

The results showed that most of the penguins had been exposed to these contaminants. The scientists detected PFAS in about 91% of the bands and identified nine different compounds, including both highly toxic legacy PFAS used before 2000 and newer replacement chemicals, which are less likely to accumulate in tissues but are still highly persistent and in widespread use today. Exposure also varied between colonies, seasons, and the length of time the bands remained on the birds, suggesting marine PFAS levels change across space and time.

Penguins are particularly suited for this work because they forage across large areas of the ocean but reliably return to the same breeding colonies, making it possible to deploy and retrieve monitoring devices. But Uhart and her colleagues hope to expand their network by placing the samplers on other species. Next on the list: cormorants, birds capable of diving more than 50 meters below the surface, deeper than penguins can go.

But Uhart emphasizes that the penguin study was only a pilot, with a small sample size and study period. Even so, the technique’s low cost means it could be replicated in larger penguin populations and across more regions, Frere says . “Not all of the Argentine sea is the same.”

Despite the pilot’s small size, Dee Boersma of the University of Washington sees promise in the idea. She notes that penguins are more than mere monitors for their habitats. They’re also charismatic species that can quickly capture human attention and deliver an urgent message. “We don’t really know what these chemicals are doing—but penguins are in trouble,” she says. “We’re losing our sentinels.”

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Long-delayed plans for a new U.S. icebreaker to serve scientists working in the Antarctic received an unexpected boost last week from President Donald Trump when he included it in his 2027 budget request to Congress . Antarctic researchers are thrilled that Trump has made building the new ship part of what he calls “restoring American maritime dominance.” But they acknowledge the $900 million request, part of his proposed budget for the National Science Foundation (NSF), falls far short of what’s needed to build a research vessel that could cost $2 billion or more. It’s also possible Congress won’t come through with the money.

Still, “We’re all superexcited,” says Colgate University micropaleontologist Amy Leventer. “Although the amount is not consistent with estimates of what the ship will cost, it’s a great start. We’ve been waiting a long time, and I can wait a bit longer.”

U.S. scientists have been without a research vessel dedicated to work in the icy Southern Ocean since last summer, when NSF ended its lease of the RV Nathaniel B. Palmer . Its replacement, labeled the Antarctic Research Vessel ( ARV ), would be bigger, more powerful, and more research-capable than the Palmer , with the ability to crunch through sea ice 1.4 meters thick or more at 3 knots.

The Antarctic research community began to plan such a ship nearly 2 decades ago, and has fought with NSF over its ideal configuration. In February 2024, NSF invited institutions to bid on a $2.2 billion contract to complete the design, build the ship, and have it seaworthy by 2032. That competition was suspended last year, however, and the president’s 2027 budget request is the first sign that the icebreaker—which could take almost a decade to complete—may be back on track.

Many hurdles remain before the ARV sails on its first cruise, observers say. One issue is how the White House has proposed to fund the vessel. Trump wants the $900 million to be considered mandatory, rather than discretionary, spending, meaning it would not be included in the roughly one-quarter of the federal budget that Congress must approve each year. The mandatory designation could help prevent the ship’s funding from being scuttled by conservatives, who favor tight caps on discretionary spending.

But historically, mandatory spending has only applied to programs with a dedicated stream of federal funding, such as Social Security, or written into legislation that guarantees multiyear funding. Neither is the case for the ARV , however, and budget experts say the White House’s strategy amounts to a distinction without a difference. “It’s still discretionary spending,” says one former White House budget official. “So it comes out of the same pot.”

The issue may come into focus as soon as this spring, when Congress takes up supplemental spending bills that could include the ARV . (The leading candidates are bills to fund increased border security and the Iran war, two of Trump’s priorities.) But the Republican-controlled Congress is divided on what exactly should be included in those bills, so the White House would need to advocate for the ARV against stiff competition.

Another issue is whether, even if the ship is built, NSF will be able to fund scientists to use it. Trump has now twice proposed cutting NSF’s budget by more than half, and his recent request for the 2027 fiscal year that begins on 1 October includes a 71% reduction for polar research. If Congress agrees to that request, it would undermine NSF’s support for the U.S. academic fleet, 16 ships operated by the University-National Oceanographic Laboratory System, a consortium of 58 marine institutions. As one science policy veteran puts it, “The NSF budget is negative for polar science, but positive for maritime hardware, which could lead to nice ships, but fewer funded [principal investigators] on them.”

Fewer grants would also translate into less support for the next generation of scientists to work on the research ship. “It’s important that we continue to grow the community so that we can take advantage of this new vessel,” says Julia Wellner, a marine geologist at the University of Houston.

Despite those concerns, research advocates are heartened that Trump included the ARV in a four-page summary of his 2027 budget request that touts “the largest shipbuilding order by any administration” since World War II. University of Rhode Island biological oceanographer Paula Bontempi says the ARV ’s mission fits well with the administration’s goal of strengthening the U.S. presence in the Southern Ocean, in particular given a growing Chinese fleet of polar-class icebreakers.

“We all know how the Antarctic is strategically important to national security,” says Bontempi, who co-led a National Academies of Sciences, Engineering, and Medicine panel in 2024 that endorsed building the ARV and who chairs the Ocean Coalition, an advocacy group for academic ocean science. “A state-of-the-art research vessel for doing discovery science would contribute to everything from satellite monitoring of trade routes to exploring the potential for mining natural resources.”

At a minimum, the ARV ’s advocates are hoping Congress finds room in the final 2027 NSF spending bill for the agency to hire a contractor that can complete the design for the vessel. That would be a major victory, says Wellner, who holds out hope that NSF’s budget will eventually grow to accommodate the cost of building and operating the icebreaker.

“The ship is almost a decade away,” she says. “And there’s a lot of positive things that could happen in the meantime.”

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Ribosomes are some of the most fundamental molecular machines on Earth: the proteinmaking factories for all living things. And until recently, they were thought to be pretty much identical, at least within a species.

But there’s growing evidence of natural variation in the genes coding for the RNA molecules that help make up a ribosome’s structure. Now, a new study, based on data from hundreds of thousands of people in the UK Biobank, suggests this variation could influence human traits such as height and weight —and perhaps represents a major overlooked driver of human diversity.

“It’s a very nice contribution,” says Scott Blanchard, a structural biologist at St. Jude Children’s Research Hospital who was not involved in the work, published today in Cell Genomics . The study concludes “that, yes, there is a correlation between RNA sequence variation and human phenotype,” he says. “That’s really new.”

Each animal cell can contain millions of ribosomes, which consist of dozens of distinct proteins enfolded in strands of nucleic acid called ribosomal RNA (rRNA). These tiny machines translate messenger RNAs—transcripts from active genes—into proteins needed for cell survival, growth, and other functions. Most scientists thought that to work properly, they couldn’t vary much.

But that view has been challenged over the years. In the 2010s, for example, a team led by molecular and developmental biologist Maria Barna at Stanford University analyzed ribosomal proteins and concluded that even within a single mammalian cell, there are multiple types of “specialized” ribosomes dedicated to churning out different cellular proteins.

Others have studied the genes that code for rRNA molecules, which are present in hundreds of copies across the genome. It’s a challenging task—the repetitive nature of the sequences presents obstacles for traditional genetics techniques, and different approaches can yield wildly different results. Still, multiple groups, including Barna’s and Blanchard’s, have documented some degree of variation , both between people and within a single person’s genome .

There are hints such variation could have biological consequences: Experiments in bacteria by Blanchard’s group showed that altering expression of different rRNA sequences changes which proteins get synthesized. Studies in humans have found associations between certain mutations and cancer, though it’s often difficult to confirm whether a mutation was present from birth and whether it’s a cause or consequence of disease.

Vardhman Rakyan, a molecular geneticist at Queen Mary University of London (QMUL), has been studying rRNA using the massive collection of genomic and health data in the UK Biobank. In 2024, his team reported associations between the number of rRNA gene copies in a person’s genome and traits such as white blood cell count and body mass . People with obesity, for example, tended to have fewer rRNA gene copies—though the reasons were unclear.

In the latest study, his team looked for differences in the gene sequences themselves. QMUL molecular geneticist Francisco Rodríguez-Algarra first searched the genomes of 49 pairs of identical twins in the biobank database, looking for rRNA gene mutations shared by both people. That way he was more likely to capture mutations present from birth and avoid spurious variation due to DNA sequencing errors or other noise. The search turned up several hundred variants, most of them differences in single DNA bases.

The researchers then used data from about 300,000 other biobank participants to look for associations between these variants and human traits. Among several dozen hits, they found a link between certain rRNA gene mutations and a person’s body size. Mutations clustered within a gene coding for the largest RNA in the ribosome were linked to height, weight, waist circumference, and cholesterol levels.

Those associations likely emerged partly because almost every participant in the biobank has contributed height and weight measurements. Other health or lifestyle data are patchier, making it harder to find statistically significant associations. Rakyan says there may be much more variation the team didn’t capture because it focused on variants found in such a small number of twins, all of whom were white.

Rakyan’s group isn’t the only one investigating such associations. Last year, after his team posted its current study as a preprint , Barna and colleagues posted their own preprint analyzing rRNA gene variation in the UK Biobank . Using a different approach in its analysis, the group identified some similar connections between rRNA variation and body size, but suggested additional links to physiology, various diseases, and ribosome function.

“It’s really exciting to think about this variation in the human population,” says Julie Aspden, a ribosome researcher at the University of Leeds who was not involved in the work. She notes it’s unclear exactly how rRNA gene variants could influence the traits observed in the new study. The paper suggests some of these mutations alter rRNA structure, changing how these strands interact with other ribosome components. That might change ribosomes’ “preference” for making certain proteins, Aspden says. Her own group is investigating a similar idea, studying how rRNA modifications can affect translation .

Some researchers have speculated ribosome diversity could eventually be a target for novel therapies . “If the ribosomes that are expressed in [cancer] are actually physically different,” Blanchard suggests, “maybe we could target them with small molecule [drugs].”

Rakyan’s team is now planning a new rRNA gene analysis on a large data set of cancer tissue samples. As people look closer at these long-overlooked sequences, Rakyan says, “there’s going to be—hopefully—a huge explosion of discovery.”

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In the deep sea, female anglerfish can attract prey with a glowing lure that wiggles on the end of a long, specialized spine. The trick could serve a second vital purpose, two researchers argue in a new study: The light may help them hook up with mates , which in turn might have led to a burst of new anglerfish species.

To Kory Evans, an evolutionary biologist at Rice University who wasn’t involved with the research, the scenario makes sense. “One of the puzzling questions with deep-sea anglerfishes is how a tiny male finds its mate in the giant, dark sea,” he says. Better communication between mates may well have shaped the diversification of deep-sea anglerfishes, Evans says—with the female’s lure providing a guiding light to potential suitors.

Bioluminescence has evolved many times in the ocean for various purposes. Near the surface, it can serve as camouflage, making the undersides of fish blend into lighter water. Squids and worms release glowing chemicals as a decoy when threatened. And bioluminescence can help crustaceans and other animals find mates .

Alex Maile, a Ph.D. student at the University of Kansas, found himself drawn to the glowing lures of anglerfishes. For his master’s research at St. Cloud State University, Maile studied the evolutionary history of anglerfishes, carefully building a family tree of nearly all 74 living genera, using DNA and the fishes’ anatomical traits, which he checked using measurements from museum specimens. Thirteen fossils helped pin down when various groups first evolved. “The first thing that blew me away was the amount of diversity in the morphology of the lures,” Maile recalls.

In the new study—recently published in Ichthyology & Herpetology —Maile analyzed the types of lures various species of anglerfishes employ. About 72 million years ago, species living in relatively shallow water evolved the group’s first lures: simple, nonglowing balls of tissue at the end of spines that could be wiggled. After anglerfishes moved into the open ocean and deeper water, roughly 34 million to 23 million years ago, they began to host symbiotic, bioluminescent bacteria inside the lures.

Maile and his adviser at St. Cloud, evolutionary biologist Matthew Davis, noticed that the lure spines are generally about three times longer in species with bioluminescent lures than in species with no shine. The pair speculates that this extra distance prevents the glowing lure from illuminating the anglerfish, keeping its gaping mouth and sharp teeth hidden in the shadows.

A bigger impact of the light, Maile and Davis think, could be in helping males locate females. Male anglerfish lack lures completely and are much smaller than their better halves. But they do have large chambers in their heads, apparently for detecting females’ pheromones and other scents—and they have big eyes with which they may spot the glimmer of a potential mate. After ancient deep-sea anglerfishes switched on their lures, the group began to evolve new species about two to three times faster. Thanks to that rapid diversification, deep-sea anglerfishes now comprise 43% of the 408 living species of anglerfishes.

A guiding light deep in the dark may sound enchanting, but the next steps in anglerfish reproduction are less romantic. A male permanently latches onto the female, relying on her blood for food. His brain and other organs dissolve, except for his testes. Then the female releases her eggs into the water and the male his sperm. Bizarre though it may seem to us, the reproductive strategy evidently works. “The evolution of this group may be driven because of the sexual attraction of the lures,” Maile says. “That’s the fun, weird part about all this.”

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Astronomers routinely see galaxies crashing into each other and combining. But the final phase of these cosmic mergers has long proved elusive: two supermassive black holes, each once occupying the center of its own galaxy, closely circling each other within a single, combined galaxy. Now, researchers say they have found compelling evidence of such a pairing. A distant galaxy seems to be firing off two beams of radiation from its center at different angles—a sign that a pair of supermassive black holes lurks at its heart.

The two behemoths—each with a mass as large as 1 billion Suns—seem to orbit each other every 121 days. The duo’s dance cannot last forever. In as little as 100 years, the researchers say, the black holes should collide, shaking spacetime itself in a titanic burst of gravitational waves. That final burst “would be a really fantastic gravitational wave signal,” says team leader Silke Britzen of the Max Planck Institute for Radio Astronomy.

Previous binary black hole candidates have failed to be confirmed, so independent experts are cautious about the discovery. “It’s messy, but it does look like two jets, which would require two black holes,” says Zoltan Haiman, an astrophysicist at Columbia University. “To be honest, it’s very complicated. … I would say it’s still only a candidate.”

Galaxies can be seen across the cosmos merging with each other. Astronomers know our own Milky Way has consumed smaller neighbors, based on filamentous “streams” of stars and chemical differences between stellar populations, and they forecast it may collide with the nearby Andromeda galaxy in 4.5 billion years . The black holes thought to lie at the heart of nearly all galaxies should merge, too, which helps explain how some reach masses many billion times that of the Sun.

During a galaxy merger, the black holes are unlikely to collide head-on. Instead, they shoot past each other and settle into orbit around each other, forming a binary pair. Over hundreds of millions of years, the two black holes inch closer to each other, losing energy initially via friction with the galaxy’s stars and gas and later through the emission of gravitational waves, ultimately spiraling into a merger.

Astronomers have long searched for evidence of supermassive black hole binaries within a single galaxy, but even the sharpest eyed telescopes can’t resolve two black holes when they’re right next to each other. Instead, astronomers look for periodic signals coming from galactic centers that would indicate orbiting black hole pairs. But galaxy cores are messy places, often full of spinning disks of gas and jets of material emanating from the black hole’s poles. It has proved hard to pick out the definitive signal of binary orbits .

Now, Britzen’s team believes it has found such a signal, as described in a paper accepted for publication in the Monthly Notices of the Royal Astronomical Society . The candidate signal comes from Markarian 501, a galaxy some 500 million light-years from Earth whose nucleus is so active, it’s referred to as a “blazar.”

The center of Markarian 501 is rapidly consuming matter while also channeling some of it into a jet of high energy particles and powerful radio waves that just happens to be pointing roughly toward Earth. Oddities in that radio signal led some to suspect there might be a black hole binary at the heart of Markarian 501, so Britzen and her team took a look.

If the black hole producing the jet was one of a pair, the jet would appear to move over time. So Britzen’s team downloaded 23 years’ worth of data on the blazar gathered by the Very Long Baseline Array, a network of radio dishes spanning the United States. At first, the researchers didn’t see any motion, so they shifted to a higher frequency to track what was happening closer to the black hole. Suddenly they saw a different signal—one pointed away from Earth. “That was not to be expected,” Britzen says.

The team concluded that the second signal represented a second jet, presumably coming from a second black hole. They also noticed variations in the brightness of the source that repeated every 121 days, suggesting the orbital period of the two black holes. “It is intriguing that this [second jet] seems to behave differently than the other jet … suggesting a different origin,” says Daniel D’Orazio of the Space Telescope Science Institute. But, he says, finding a binary so close to merging would be almost too good to be true. “If this is confirmed as a binary then we are either very lucky, or the demographics [are] not as we expected, implying many more such systems,” he says. If it were the latter, he asks, why haven’t observers found more evidence of these binaries by now?

Britzen believes she won’t have to wait that long to see whether she’s right. If the binary is that close to merging, astronomers should be able to measure its orbital period shorten over the next decade. In addition, the pair should already be giving off gravitational waves that may be detectable by measuring slight changes in the metronomic signals of networks of fast-rotating stars called pulsars . “There is hope,” Britzen says.

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Chimpanzees regularly fight viciously over food, mates, and rank, but only rarely do these brawls spill over into a broader civil war. Now, a study tracing 30 years of chimp behavior in Kibale National Park in Uganda reveals how and why such internecine violence erupts. The study, described today in Science , shows how in chimps—and perhaps humans—tensions in once-peaceful groups can grow into deadly violence, even without resource shortages or cultural divisions to fuel them.

“This study demonstrates beautifully the analytical power gained through sustained research,” says Roman Wittig, a primatologist at the Max Planck Institute for Evolutionary Anthropology who studies chimps in Ivory Coast’s Taï National Park. Primatologist Richard Wrangham, who in 1987 kicked off his own study of a neighboring chimp community in Kibale, says the new study is “terrific” and both clarifies motivations for human warfare and spotlights how we differ from one of our closest relatives.

Researchers in 1995 began to study the Kibale chimpanzees in a densely forested area called Ngogo, carefully tracking their movements and social networks. At one point, there were more than 200 individuals, the largest community of chimps ever studied. They lived in two main social groups, designated as Central and Western, that peacefully intermingled, with many cross-group matings.

But on a fateful day in June 2015, some chimps from the two clusters met up near the center of their territories, and the Central chimps chased the Western ones away. Afterward the two clusters avoided each other, and reproduction between the groups stopped. Western males regularly began to patrol in Central territory, looking to expand their domain.

In 2017, the tensions boiled over. A group from the Western cluster attacked and injured the Central group’s alpha male. Between 2018 and ’24, the researchers estimate, males in the Western group killed seven adult males and 17 infants in the Central group. Yet even though they were larger in number, the Central group males curiously never ganged up to kill any of the Western chimps.

What sparked the violence? Animals that turn from friend to foe are often competing for scarce food. But at Ngogo, “there was still a lot of food in this forest,” says Aaron Sandel, a primatologist at the University of Texas at Austin and the study’s first author.

One contributing factor, says co-author John Mitani, a primatologist at the University of Michigan who helped establish the Ngogo research site, is that “the Ngogo chimps were victims of their own success. The group continued to grow and grow and grow, and it reached the size that individuals couldn’t pull together anymore.”

The social bonds between the males may also have frayed as the community lost some of its critical peace brokers: In 2014, five adult male chimps died within about 1 month of one another, possibly from disease. “Some of those adult males were important connectors,” Sandel says.

Reproductive competition could have played a role in the fission. The Central group was larger, and for unknown reasons, those males appeared to have lost access to females in the Western cluster before the war broke out. “I can easily imagine a situation that, if you’re a Central male, you’re saying to yourself, ‘Wait a second, we’ve been cut off from these females, maybe now’s the time to try to do something about that,’” Mitani says. “But those guys badly miscalculated, because they’re the ones who have been victimized and have suffered all the killings, which is another unusual aspect of the story.”

As the researchers note in their report, chimps aren’t divided by religion, language, politics, and ethnicity. “You do not need ideology to generate hostilities,” says Wrangham, an professor emeritus at Harvard University. “The motivations for warfare are much more concerned with our biology than people would have believed a long time ago.”

In the early 1970s, Wrangham, whose book, Demonic Males: Apes and the Origins of Human Violence , explores the link between apes and the origin of human violence, helped document a similar fission in the chimp community in Gombe National Park in Tanzania that Jane Goodall made famous. That led to what researchers called “the 4-year war,” in which one group killed six males and one female from a second group. The lead-up to violence in Kibale “fits entirely in my mind with what happened in Gombe,” Wrangham says, “but it’s much more informative in many ways.”

Critics of the Gombe work have noted that the researchers gave the chimps bananas at a feeding station, altering their behavior—and some have contended that it drove the lethal attacks. Wrangham acknowledges the provisioning had a “muddling impact” on the results. But he maintains that the division of the Gombe community into two warring factions “was very clear” and catalyzed by a rift between two ranking males—which he suspects played an important role in Ngogo, too.

Primatologist Catherine Crockford, who co-directs the Taï Chimpanzeee Project with Wittig, cautions that the “impressive and insightful study” at Ngogo does not rule out the possibility that cultural differences increased tensions between the groups. Even in the absence of language, chimpanzees have distinctive ways to communicate, which Crockford studies. As she has shown, groups of chimps can learn specific pant hoots that can reinforce bonds, and she wonders whether shared vocalizations might have gradually “fed increasing hostilities.”

The lessons for human conflict only go so far. Wrangham notes that unlike humans, chimps do not seem to commit revenge killings, likely because they don’t have language. “In humans, the first thing that happens when a member of your community, your band, your village, gets killed, everybody gets together and says, ‘OK, well, what are we going to do about it?’” Wrangham says. “You don’t have revenge killings in chimps, because in order to be able to conduct revenge, you need to discuss a plan.”

Mitani says the study ultimately helps explain chimp behavior more than our own. “One of the unusual things about us as humans is that we’re an incredibly pro-social and cooperative species,” he says. “Instead of attacking our neighbors, we go out of their way to help them, even if they are complete strangers. That’s the lesson I learned from all this. I try to be optimistic, especially in these times as the world becomes increasingly polarized.”

A cancer cell slowly detaches from its parent tumor and begins to worm into the tough surrounding tissue. When the itinerant cell reaches a nearby blood vessel, it pushes through the outer wall and catches the rushing current like a kayaker shooting rapids. After riding the bloodstream for a few seconds to a few minutes, the cell pulls out at a promising location, exits the vessel, and begins to divide, establishing a new beachhead for the cancer.

Such cellular expeditions are all too often deadly for patients. Up to 90% of cancer deaths result from these tumor spinoffs, known as metastases, rather than from the original mass.

But metastasis is also perilous for the wandering cells. As cancer biologist Nicola Aceto of ETH Zürich puts it, the bloodstream is like “a very rough river populated by piranhas.” The chances that a tumor cell will survive the trip and thrive elsewhere are minuscule. Still, conventional wisdom long held that despite the risks, most tumor cells attempt the voyage alone.

In fact, they often do it in company, forming clusters that can contain from two to more than 100 members and often include nontumor cells (see graphic, below). Over the past decade or so, Aceto and other researchers have documented that collective travel offers a big advantage to the malignant cells.

“Clusters of cancer cells are so much better at seeding metastases than individual cancer cells,” says Andrew Ewald, a cancer cell biologist at Johns Hopkins University.

In breast cancer, for example, animal studies suggest the clumps, known as circulating tumor cell (CTC) clusters, may be 50 to 100 times more likely to produce successful metastases than are solitary cells. “When we find these clusters in the blood, it’s a really bad prognostic sign,” says cancer biologist Kevin Cheung of the Fred Hutchinson Cancer Center.

At the same time, the conglomerations offer new opportunities to probe and perhaps stymie metastasis. The process has been hard to study, but CTC clusters can be sieved from blood draws, which “makes it easier to determine what makes [them] lethal and how to stop them,” Ewald says. Researchers have already performed the first clinical trial of a potential treatment to target the clusters, the heart disease medication digoxin, which blocks a protein channel that helps cells cohere. The drug modestly shrank the clusters’ average size in patients with breast cancer, Aceto and colleagues reported in 2025 in Nature Medicine .

The researchers didn’t track the patients long enough to determine whether digoxin provided any clinical benefit, but Aceto says the shrinkage was encouraging. Now, he says, “We need a more active, cancer-specific version of digoxin.”

A company that Aceto co-founded, PAGE Therapeutics, has been developing compounds that are better at breaking up clusters and is planning to test them in a safety trial, he says. And scientists are seeking other ways to disperse the clusters or stop them from forming in the first place. “We have seen that CTC clusters are closely associated with patient survival,” says cancer biologist Huiping Liu of the Northwestern University Feinberg School of Medicine. By tampering with clusters, she says, researchers hope to give patients added time and improve their quality of life.

Up to 1 billion cells may flee a primary tumor each day, and scientists have long recognized that they sometimes travel together in the bloodstream. For example, pathologists examining tissue samples sometimes found clotlike bunches of cancer cells, or tumor emboli, lodged in capillaries.

In 1953, pathologist Satoru Watanabe of the Yale School of Medicine became one of the first to study how clusters contribute to metastasis when he injected some mice with clusters of tumor cells and gave others the cancer cells separated into a slurry. All but one of the animals that received the globs developed lung metastases, whereas none of the mice injected with detached cells did. Later studies that used similar methods also suggested that by bunching up, cells improved their odds of metastasizing. Still, most scientists overlooked these results and focused on the capabilities of lone cells.

New ways to capture and track clusters made them harder to overlook. In the early 2000s, cancer biologist Dan Haber and biomedical engineer Mehmet Toner, both of Harvard Medical School, and their colleagues were crafting microfluidic chips, small devices crisscrossed with hair-thin networks of channels. The researchers used the chips to analyze patients’ blood samples and isolate individual cancer cells, which they thought would be handy for diagnosis. Sometimes, however, the devices trapped clusters of cells, Haber recalls. He decided to take a closer look at these rare aggregations. “I had no idea it would end up being so fascinating,” he says.

Aceto nearly missed his chance to work on that study. After finishing his Ph.D., he almost quit research. He and his wife had just had their first child, and an academic career seemed too uncertain. “Ultimately I just followed my passion” and started a postdoc in Haber’s lab in 2012, he recalls. “As soon as I arrived, I realized the potential of CTC clusters and focused all my work on these.”

The first challenge was to develop a way to label clusters so that researchers could track them and determine whether they spawned metastases. Aceto and colleagues genetically modified human breast tumor cells to manufacture either a green or a red fluorescent protein. When a bicolored blend of the cells was injected into mice, it spawned tumors that were also a mixture of both colors—as were almost all of the clusters these tumors spun off into the bloodstream.

Then Aceto and his colleagues performed the acid test—examining metastases from the animals’ lungs under the microscope. If the masses descended from individual cells, they would be either all green or all red. But if the metastases grew from groups of cells that had plied the bloodstream together, they would be mottled. “We saw the metastases were largely multicolored,” Aceto recalls. “That was when we had the first beer to celebrate,” he says.

Cancer’s cluster bombs

The bloodstream is a dangerous environment for a solo cancer cell. Wandering tumor cells often huddle together, thereby boosting their chances of arriving at a promising location to start a new tumor.

Many tumor cells travel alone, entering the bloodstream by squeezing through vessel walls.

Lone tumor cells can be attacked by immune cells, destroyed by forces produced by flowing blood, or commit suicide.

However, cancer cells often depart the tumor in a group that can include immune cells.

By contorting into a different shape, a bunch of cancer cells can cross into the bloodstream.

There, the circulating tumor cell cluster begins a journey during which it may pick up platelets that provide protection.

As tumor cell clusters travel, they can jam narrow capillaries, leading to clots.

But clusters can also reform into a conga line of cells and slip through the narrow passages.

If a tumor cell cluster survives its voyage through the bloodstream, it may exit through a vessel wall.

The cells may then start to divide, yielding a new tumor mass that can be fatal for the patient.

C. BICKEL/ Science

The results, published in Cell in 2014, and other studies helped spur a re-evaluation of the clusters. Researchers still think single cells instigate many metastases. But “the evidence is strong” that clusters are important contributors as well, Liu says. And scientists have found that a variety of other cell types can huddle with the tumor cells and help them on their way, including platelets, immune cells, and fibroblasts.

Along with microfluidic chips, researchers have enlisted several other technologies to identify CTC clusters. CellSearch, a commercial test, relies on antibodies sensitive to signature proteins from the epithelium. This protective tissue covers or lines many parts of the body—including the skin, intestines, mouth, and lungs—and is the source of most cancers. With methods like these, scientists have detected tumor cell bunches in patients with a range of cancer types, including breast, prostate, pancreatic, colon, and lung.

But the clusters only turned up in a subset of patients, and they were scarce. In the circulation of a person with cancer, there may be one tumor cell for every 10 billion blood cells—and the clusters are even rarer, most studies suggest.

Biomedical engineer David Juncker of McGill University thinks those findings understate the real abundance of clusters. He and his colleagues suspected that detection methods such as microfluidic chips are rough enough to break up many clusters, distorting the numbers. The scientists devised a different approach, filling vertical tubes with blood and allowing it to trickle through filters—a separation method that is less likely to fragment a cluster than pumping fluid through a chip, Juncker says. All 30 of the cancer patients tested with the new approach had clusters in their blood, he and colleagues revealed in 2025 in Communications Medicine .

And in 10 of the patients, the bunches were more common than individual tumor cells. “If you are more gentle, more people have them and in some patients they can be the majority” of circulating cancer, Juncker says.

The prevalence of clusters in a person’s blood can signal cancer severity, with the number of aggregations climbing as the disease progresses. A 2025 study in Nature Medicine suggests the cell clusters also augur death—or may even promote it through a mechanism unrelated to metastasis. A team led by Aceto and two colleagues from the University of Texas Southwestern Medical Center, hospice physician Kelley Newcomer and cancer biologist and surgical oncologist Matteo Ligorio, measured circulating clusters in blood samples from hospice patients with terminal cancer. In the days before the patients died, the number of clumps surged. Whether the rise directly contributed to the patients’ demise or reflected another deadly process is unclear, Ligorio says.

For metastasizing cancer cells, companions ease the rigors of the journey. “It’s a decathlon,” Ewald says. Much as decathletes have to excel at events as diverse as the long jump, discus throw, and pole vault, migrating cells face disparate challenges, such as traversing the extracellular matrix, entering blood vessels, and growing in a new environment.

Riding the bloodstream may pose the biggest challenge. Although metastasizing cells only spend a short time in circulation, during that period “they are not happy,” Haber says. For one thing, blood flowing through a vessel produces a wrenching force that can rip a cancer cell to pieces. When isolated from their brethren, cancer cells often kill themselves through a process called anoikis. A lone tumor cell is also easier prey for immune cells—the piranhas Aceto mentioned. In principle, joining a cluster should protect a cell from all three hazards.

Clusters are not mere globs of cells clinging to each other for dear life, however. Researchers have found that the cells cooperate and adapt. They may change their nature to become more like stem cells, whose ability to divide and diversify may help them take root at a new location. The cells even form unique structures that may boost their odds of survival.

Studying clusters shed from melanomas in zebrafish, for instance, cancer cell biologist and oncologist Richard White of the University of Oxford and colleagues discovered that the cells often adopt a specific arrangement. The tumors themselves can contain two subtypes of cells—one variety that is particularly good at invading tissues and a second that is adept at proliferation. In the clusters, the invasive cells usually position themselves on the outside, whereas the proliferative cells nestle in the interior. This organization, reported in 2021 in Developmental Cell , could be advantageous, White suggests, because the invasive cells might shield their fellow travelers from the immune system.

The cells aren’t necessarily locked into position, Haber, Toner, and colleagues have found. Clusters can change shape when they run into obstacles. Many of the cell globules are large enough to get stuck in capillaries. But they sometimes make it through the small-bore vessels. To find out how, the scientists forced clusters to cross a microfluidic chip with narrow channels. To their surprise, the balls of cells elongated into chains that could slip through the passages single file. Afterward, they returned to their original shape, the scientists reported in a 2016 paper in the Proceedings of the National Academy of Sciences ( PNAS ). “They come out looking like a hot dog, and within seconds they reorganize into a cluster,” Haber says.

So far, no cancer treatment specifically blocks metastasis. But the discoveries about how CTC clusters form and function suggest several ways to prevent clusters from spreading cancer. Aceto and colleagues have made the most progress. They tested nearly 2500 approved drugs to determine whether they could break up the clusters in a culture dish. Two of the best performers block the sodium-potassium pump, a protein that swaps the two ions across the cell membrane. That finding made sense because studies had suggested that inhibiting the pump weakens the connections between cells.

To assess whether this mechanism works in the body, Aceto and his team in 2020 launched the phase 1 trial of digoxin, the heart failure drug that inhibits the sodium-potassium pump, in patients with breast cancer. The researchers collected blood from the patients, dosed them with digoxin for 7 days, and then took more blood samples. The clumps in the patients’ blood shrank by about two cells over that week. PAGE Therapeutics’s first safety trial of a more potent cluster-busting compound could start as soon as next year, Aceto says.

Another possible way to split up clusters comes from biomedical engineer Anne-Laure Papa of George Washington University and co-workers. As the conglomerations wend through the circulatory system, they can accumulate the protein fibrin, a cablelike component of blood clots that lashes the cancer cells together. Clot-forming cell fragments known as platelets often cloak the clumps. In one set of experiments, the scientists made what they called platelet decoys by soaking the cell shards in detergent, which prevents them from causing clots. The researchers then packed the decoys with tPA, a clot-busting drug for treating heart attacks and strokes that dissolves fibrin, and injected them into mice that had also received injections of tumor cell clusters.

Compared with animals that received tPA alone, the mice dosed with the platelet decoys developed smaller metastases and survived about 10% longer, the researchers reported in 2024 in Advanced Healthcare Materials . “Additional work will be necessary prior to a clinical trial,” Papa says, such as fine-tuning “the dosing and injection schedule.”

Dispersing tumor cell clusters may not be enough. “The question that remains is if you break them up, how much do you reduce the metastatic potential?” Cheung says. Liu thinks a multipronged strategy will be needed to thwart the clusters. “We wish it was simple enough to be one magic bullet. The reality is, it’s complex.” Researchers will likely have to hit the clusters with several drugs, including compounds that increase their vulnerability to the immune system, she says.

Her lab has found that the tumor clusters circulating in breast cancer patients often harbor a rare type of immune sentinel known as a double-positive T cell. Sporting the CD4 and CD8 receptors, these cells account for less than 0.1% of T cells in the blood, but they make up more than 14% of immune cells in the patients’ CTC clusters, the scientists revealed in 2025 in the Journal of Clinical Investigation . The cells’ presence boosted the chances that a cluster would metastasize in mice. And the analysis by Liu’s team also suggested the cells help suppress immune attacks on the clumps.

To join a cluster, the researchers revealed, a double-positive T cell requires another receptor on its surface, VLA-4, that connects to a matching protein on a tumor cell. Liu and colleagues determined that giving mice with implanted tumors an antibody that blocks VLA-4 reduced metastasis and more than doubled the odds that the animals would survive for at least 6 weeks. A human version of the antibody, natalizumab, has already been approved for treating multiple sclerosis and Crohn disease. Liu says she and her team are trying to organize a clinical trial of the drug in patients with breast cancer. They are also developing a compound to block a different protein that protects clusters from the immune system.

The best way to curb metastasis, Cheung says, may be to stop the clusters from forming in the first place. When cancers reach a certain size, they often undergo necrosis, in which the interior of the mass dies. The number of clusters in the blood of rats increased 10-fold when necrosis set in, Cheung and his colleagues reported in 2023 in PNAS . When the researchers implanted tumors that lacked a key protein necessary for necrosis into the animals, however, clusters almost disappeared. “We find that if you prevent necrosis, you reduce CTCs and CTC clusters to zero,” Cheung says. His lab is now trying to create an antibody that targets the protein and shuts down necrosis.

For a cancer cell, belonging to a cluster doesn’t guarantee it will reach a new home. But traveling in packs seems to give wandering cells just enough of an edge for a few to complete their death march. Cancer researchers now hope to tip the odds back against the cells—and in patients’ favor.

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If true, a claim reported by the New York Post and repeated by President Donald Trump would be perhaps the single biggest breakthrough to date in the budding field of quantum sensors. On 7 April, the Post reported that the United States rescued a jet pilot shot down in Iran last week with the help of magnetic quantum sensors that detected his heartbeat . Scientists say such devices can sense a beating heart, but at a distance of a few centimeters and not, as Trump suggested the day before at a press conference, at more than 60 kilometers.

“That really sounds implausible,” says Ronald Wakai, a medical physicist at the University of Wisconsin–Madison who has spent decades developing techniques to monitor the heart magnetically. Dmitry Budker, a physicist at Johannes Gutenberg University Mainz who works with the same type of sensor mentioned in the Post story, shares those doubts. “I would be extremely skeptical,” he says.

Called Ghost Murmur, the purported technology was developed by Lockheed Martin, the Post reported. “In the right conditions, if your heart is beating, we will find you,” an anonymous source told the paper. According to the story, signals are detected by tiny defects in diamonds in which a carbon atom is replaced with nitrogen and a neighboring atom is missing. That nitrogen-vacancy (NV) center can trap a single electron that in a magnetic field twirls like a compass needle, making it a quantum sensor.

The heart does emit magnetic signals, driven by ions flowing along cardiac neurons. However, those signals are extremely weak. On the surface of the chest of an adult, a few centimeters from the heart, they measure about 0.1 nanotesla, roughly a half-millionth as strong as Earth’s magnetic field. To monitor the heart, physicians instead rely on its stronger electric field, which can be easily sensed with electrodes on the chest, a technique called electrocardiography.

Still, since the 1960s, scientists have traced magnetic signals from the heart with ever-greater precision, thanks to improving sensors. For example, Wakai and colleagues use a device called an optically pumped magnetometer, which contains a small volume of magnetically polarized rubidium gas, to sense magnetic fields as weak as 1 picotesla, one-hundredth that of a beating heart’s signal. Similar sensitivity can be attained with electrical gizmos called superconducting quantum interference devices (SQuIDs).

But detecting such magnetic signals from a distance is another matter, Wakai says. The strength of the heart’s oscillating magnetic field fades with the square of the distance, he says, so a signal that is just barely detectable at a few centimeters will be only one-trillionth as strong at tens of kilometers. Wakai has tried to detect cardiac signals from adult patients at a distance. “Once you get past about a meter or so, you can’t see anything,” he says. However, Trump reiterated the claim that Ghost Murmur helped find the pilot.

Another problem is environmental noise, which can easily swamp the faint magnetic signal, notes Janette Strasburger, a pediatric and fetal cardiologist at the Medical College of Wisconsin with whom Wakai collaborates. Such interference would abound if a detector was placed in a vehicle such as a helicopter, she notes. “Just the rotor alone would be a killer, I’d think.” Even if the detector could sift the tiny signal from the noise, it couldn’t tell which direction it was coming from or where the person is, Wakai says.

Wakai also questions the use of diamond NV centers for remote sensing. Such detectors are not as sensitive as SQuIDs or optically pumped magnetometers, but they are very small and biologically inert. So they’re better for getting very close to tiny magnetic sources such as individual cells, Wakai says. In January, Budker and 29 colleagues reported using diamond NV centers to detect a heartbeat , although doing so required hovering over the patient’s chest for 5 minutes, according to a paper posted to the arXiv preprint server. “I thought we were the first,” Budker says.

Magnetic monitoring of the heart, or magnetocardiography, does have its uses. It’s ideal for monitoring the heart of a developing fetus, even though it produces signals only one-tenth as strong as those from an adult. Electrocardiography doesn’t work on a fetus, Wakai says, because it is covered with a fatty substance that blocks electrical signals.

Strasburger and Wakai have examined more than 1100 pregnant patients with magnetic sensors, which can reveal details ultrasound will miss. In 40% of the tests, they either confirmed the fetus had a suspected abnormality or found a different one, some controllable with measures as simple as diet and medication. The researchers’ goal is to help prevent stillbirths, Strasburger says. When speaking with Science , she was awaiting the arrival of a woman whose fetus had a heart rate only half as fast as normal.

Strasburger worries that if the claims for remote sensing turn out to be hype, they may trigger a backlash that will discredit magnetocardiography. She also notes that the National Institutes of Health had an initiative to encourage small businesses to develop quantum sensors for such applications , but the Trump administration canceled it last year. “Look at the excitement of saving one pilot,” she says. “We could be saving half a million fetuses every decade.”