Some tattoos truly make the heart go pitter-patter.
In rats, a graphene “tattoo” stuck to the heart could treat an abnormally sluggish beat. Like a futuristic pacemaker, the device delivered electrical signals that kept the heart pumping properly, scientists report online March 25 in Advanced Materials.
The electronic device is currently a proof of concept, but a version for use in human hearts could be ready for testing within five years, estimates Igor Efimov, a cardiovascular engineer at Northwestern University in Chicago. Efimov and his colleagues have worked for years creating implantable devices that conform to the body. A main challenge is how to marry rigid electronics with soft, sometimes throbbing tissues. For most current pacemakers, doctors thread electrodes on long wires through a vein inside the heart. Every time the heart beats, some 100,000 times per day, the wires flex. Enough flexing, and the device eventually breaks, Efimov says. One solution is to use ultrathin materials that ride along with the heart’s movements, like plastic wrap clinging to quivering Jell-O.
In 2021, Efimov saw something that looked promising: a paper on graphene devices applied to the skin like temporary tattoos. Unlike the metal components often used in electronics, graphene is “atomically thin,” says Dmitry Kireev, a biomedical engineer at the University of Texas at Austin who developed the graphene tattoos. Graphene — a single layer of carbon atoms arranged in a honeycomb pattern — is an appealing material for biomedical use, says Nai-Chang Yeh, a Caltech physicist who was not involved in the work (SN: 3/14/14). “Graphene is very flexible, it’s biocompatible, it’s highly transparent, it’s highly conductive and it’s mechanically strong,” she says.
But Kireev had never placed graphene tattoos on heart tissue before. Efimov contacted him and said, “Well, would you like to try? We can help.” The researchers teamed up and tested the devices in experiments on mouse hearts and inside living rats. In the rats, the heart tattoo could correct an irregular beat by sending pulses of electricity to the organ, the team reports.
The tattoos sandwich a transparent layer of graphene between sheets of stretchy silicone and ultrathin polymer. Gold tape connects the graphene to wires that run to a power source, which sends electricity through the device.
Future versions of the tattoo will be wireless, Efimov says, perhaps using a tiny antenna to pick up electrical signals from an external device placed on a person’s chest. And one day, Efimov envisions graphene electrodes the size of rice grains injected into heart muscle. Such miniature equipment could perform pacemaker duties without the typical clunky components.
That all might sound like science fiction, but the technology is almost here, Efimov says. “Now’s the time to develop it.”
Do you peel bananas from the top or bottom? One elephant goes with a third option.
When handed a slightly browning banana, Pang Pha, an Asian elephant at Zoo Berlin, will use her trunk to break the fruit, shake the pulp onto the ground, discard the peel and then shove the pulp into her mouth, researchers report in the April 10 Current Biology. The rare behavior, previously recorded in just a few elephants, could help shed light on how the animals learn complex movements. When a zookeeper first told neuroscientist Lena Kaufmann of Humboldt University of Berlin that one of the elephants peeled bananas, she decided to test it out for herself. For weeks, Kaufmann and colleagues couldn’t get Pang Pha to replicate the behavior. That’s because the way the elephant eats bananas seems to depend on ripeness.
Pang Pha ate green and yellow bananas whole — peel and all. It was only when Kaufmann offered the gentle giant a brown-spotted banana that she revealed her peeling prowess. But the fruit can’t be too brown, Kaufmann’s team found. Pang Pha rejected completely brown bananas. Initially she would place them gently on the ground in protest. Now she throws them aside. In the company of other elephants, Pang Pha surprisingly ate most yellow-brown bananas whole. She typically saved her peeling trick for the last banana during a social feeding session.
Pang Pha may have developed the peeling ability by observing her human caretakers, the researchers suspect. Elephants learning behaviors from people is extremely rare, the team says, especially a behavior this complex. None of the other elephants at the zoo — including Pang Pha’s daughter — have been observed peeling bananas. That suggests the skill isn’t easily learned from elephant to elephant.
The new study shows the value of studying individual animals, Kaufmann says. “There’s such a rich landscape of behaviors that we lose if we only look at what all elephants have in common,” she says. “If you look at each individual elephant, you can see that they’re able to do really amazing things.”
The coastal plain of the Kamb Ice Stream, a West Antarctic glacier, hardly seems like a coast at all. Stand in this place, 800 kilometers from the South Pole, and you see nothing but flat ice extending in every direction. The ice is some 700 meters thick and stretches for hundreds of kilometers off the coastline, floating on the water. On clear summer days, the ice reflects the sunlight with such ferocity that it inflicts sunburn in the insides of your nostrils. It might seem hard to believe, but hidden beneath this ice is a muddy tidal marsh, where a burbling river wends its way into the ocean.
Until recently, no human had ever glimpsed that secret landscape. Scientists had merely inferred its existence from the faint reflections of radar and seismic waves. But in the closing days of 2021, a team of scientists from New Zealand melted a narrow hole through the glacier’s ice and lowered in a camera. They had hoped that their hole would intersect with the river, which they believed had melted a channel up into the ice — a vast water-filled cavity, nearly tall enough to hold the Empire State Building and half as long as Manhattan. On December 29, Craig Stevens finally got his first look inside. It is a moment that he will always remember. Stevens is a physical oceanographer with New Zealand’s National Institute of Water and Atmospheric Research in Wellington. He spent 90 anxious minutes that day in Antarctica with his head buried ostrich-style under a thick down jacket to block the sunlight that would otherwise obscure his computer monitor. There, he watched live video from the camera as it descended into the hole. Icy circular walls scrolled past, reminiscent of a cosmic wormhole. Suddenly, at a depth of 502 meters, the walls widened out.
Stevens shouted for a colleague to halt the winch lowering the camera. He stared at the screen as the camera rotated idly on its cable. Its floodlights raked across a ceiling of glacial ice — a startling sight — scalloped into delicate crests and waves. It resembled the dreamy undulations that might take millennia to form in a limestone cavern. “The interior of a cathedral,” says Stevens. A cathedral not only in beauty, but also in size. As the winch restarted, the camera journeyed downward for another half hour, through 242 meters of sunless water. Bits of reflective silt stirred up by currents streamed back down like snowflakes through the black void.
Stevens and his colleagues spent the next two weeks lowering instruments into the void. Their observations revealed that this coastal river has melted a massive, steep-walled cavern cutting as far as 350 meters up into the overlying ice. The cavern extends for at least 10 kilometers and appears to be boring inland, farther upstream, into the ice sheet with each passing year.
This cavity offers researchers a window into the network of subglacial rivers and lakes that extends hundreds of kilometers inland in this part of West Antarctica. It’s an otherworldly environment that humans have barely explored and is laden with evidence of Antarctica’s warm, distant past, when it was still inhabited by a few stunted trees. One of the biggest surprises came as the camera reached bottom that day. Stevens gazed in disbelief as dozens of orange blurs swam and darted on his monitor — evidence that this place, roughly 500 kilometers from the open, sunlit ocean, is nonetheless bustling with marine animals.
Seeing them was “just complete shock,” says Huw Horgan, a glaciologist formerly at the Victoria University of Wellington who led the drilling expedition.
Horgan, who recently moved to ETH Zurich, wants to know how much water is flowing through the cavern and how its growth will impact the Kamb Ice Stream over time. Kamb is unlikely to fall apart anytime soon; this part of West Antarctica is not immediately threatened by climate change. But the cavern might still offer clues to how subglacial water could affect more vulnerable glaciers.
What’s beneath Antarctica’s ice sheet? Scientists have long surmised that a veneer of liquid water sits beneath much of the ice sheet covering Antarctica. This water forms as the bottom of the ice slowly melts, several penny-thicknesses per year, due to heat seeping from the Earth’s interior. In 2007, Helen Amanda Fricker, a glaciologist at the Scripps Institution of Oceanography in La Jolla, Calif., reported evidence that this water pools into large lakes beneath the ice and can flood quickly from one lake to another (SN: 6/17/06, p. 382).
Fricker was looking at data from NASA’s Ice, Cloud and Land Elevation Satellite, or ICESat, which measures the height of the ice surface by reflecting a laser off of it. The surface at several spots in West Antarctica seemed to bob up and down, rising and falling by as much as nine meters over a couple of years. She interpreted these active spots as subglacial lakes. As they filled and then spilled out their water, the overlying ice rose and fell. Fricker’s team and several others eventually found over 350 of these lakes scattered around Antarctica, including a couple dozen beneath Kamb and its neighboring glacier, the Whillans Ice Stream. The lakes provoked great interest because they were expected to harbor life and might provide insights about what sorts of organisms could survive on other worlds — deep within the ice-covered moons of Jupiter and Saturn, for instance. The layers of sediment in Antarctica’s lakes might also offer glimpses into the continent’s ancient climate, ecosystems and ice cover. Teams funded by Russia, the United Kingdom and the United States attempted to drill into subglacial lakes. In 2013, the U.S.-led team succeeded, melting through 800 meters of ice and tapping into a reservoir called Subglacial Lake Whillans. It was teeming with microbes, 130,000 cells per milliliter of lake water (SN: 9/20/14, p. 10).
Horgan helped map Lake Whillans before drilling began. But by the time the lake was breached, he and others were becoming intrigued with another facet of the subglacial landscape — the rivers thought to carry water from one lake to another, and eventually to the ocean.
Finding these hidden rivers requires complicated guesswork. Their flow paths are influenced not only by the subglacial topography, but also by differences in the thickness of the overlying ice. Water moves from places where the ice is thick (and the pressure high) to places where it is thinner (and the pressure lower) — meaning that rivers can sometimes run uphill.
By 2015, scientists had mapped the likely paths of several dozen subglacial rivers. But drilling into them still seemed farfetched. The rivers are narrow targets and their exact locations often uncertain. But around that time, Horgan got a lucky break.
While examining a satellite photo of the Kamb Ice Stream, he noticed a wrinkle in the pixelated tapestry of the image. The wrinkle resembled a long, shallow trough in the surface of the ice, as if the ice had sagged from melting beneath. The trough sat several kilometers from the hypothetical path of one subglacial river. Horgan believed that it marked the spot where that river flowed over the coastal plain and spilled into the ice-covered sea.
In 2016, while visiting the area for an unrelated research project, Horgan and his companions detoured briefly to the surface trough to take radar measurements. Sure enough, they found a void under the ice, filled with liquid water. Horgan began making plans to study it more closely. He would return twice in the next few years, once to map the river in detail and a second time to drill into it. What he found greatly exceeded his expectations.
Scientists map a subglacial landscape Horgan and graduate student Arran Whiteford of the Victoria University of Wellington visited the lower Kamb Ice Stream to map the river in December 2019.
After weeks on the Antarctic ice sheet, they’d grown accustomed to its monotonous flat landscape, their perception sensitized to even tiny ups and downs. In this context, the surface trough “looked like this massive chasm,” Whiteford says, “like an amphitheater” — even though it slanted no more dramatically than a rolling cornfield in Iowa.
It was a week of scientific drudgery, towing the ice-penetrating radar behind a snowmobile along a series of straight, parallel lines that crisscrossed the trough to map the shape of the river channel under the ice.
Horgan and Whiteford worked up to 12 hours per day, occasionally trading positions. One person drove the snowmobile, straining his thumb on the throttle to maintain a constant 8 kilometers per hour. Two sleds hissed along behind. One held a transmitter that fired radar waves into the glacier below; the other held an antenna that received the signal reflected back off the bottom of the ice. The second person rode on the sled with the antenna, his eyes on a bouncing laptop screen making sure that the radar was functioning. Each evening they huddled in their tent, reviewing their radar traces. The river channel appeared far more dramatic than the gentle dip atop the ice suggested. Below their boots sat a vast water-filled cavern with steep sides like a train tunnel, 200 meters to a kilometer wide and cutting as much as 50 percent of the way up through the glacier. The more they looked, the more it resembled a river. “It kind of meanders downstream,” Whiteford says.
All told, Whiteford made two weeklong visits to the trough, snowmobiling over from another camp 50 kilometers away. The first time he was accompanied by Horgan, and the second time by another graduate student, Martin Forbes.
After returning home to New Zealand in January 2020, Whiteford examined a series of old satellite images. They showed that the surface trough — and hence, the cavern — had begun forming at least 35 years before, starting with a blip at the very mouth of the river, where it ran into the ocean. That blip had gradually lengthened, reaching progressively farther inland, or upstream. Whiteford and Horgan reported the observations in late 2022 in the Journal of Geophysical Research: Earth Surface — along with their theory about how the cavern formed.
In other parts of Antarctica where the ice sheet protrudes off the coastline, scientists have found that the ice’s underside is often insulated from the ocean heat by a buoyant layer of colder, fresher meltwater. That protective layer is sometimes only a couple of meters thick. But Horgan and Whiteford suspect that the turbulence of the subglacial river flowing into the ocean stirs up that protective layer, causing seawater — a few tenths of a degree warmer than the subglacial water — to swirl up into contact with the ice. This causes an area of concentrated melt right at the river’s mouth, creating a small cavity where warm seawater can intrude further.
In this way, says Horgan, the focal point of melting is “stepping back over time.” And the cavern gradually burrows farther upstream into the ice.
Whiteford used a different set of satellite measurements — which measured the rate at which the ice’s surface sank over time — to determine how quickly the ice was melting in the cavern below. Based on this, he estimated that in the upstream end of the cavern, the ice (currently 350 to 500 meters thick over the channel) was melting and thinning 35 meters per year. That’s an astronomical rate. It’s 135 times what has been measured 50 kilometers southwest of the cavern, where the ice floats on the ocean. The water temperature is probably similar at both locations. But the turbulence caused by the river transfers the water’s heat far more efficiently into the ice.
Horgan thinks that the cavern at Kamb also owes its dramatic height to another factor. Glaciers in this part of West Antarctica generally flow several hundred meters per year. So the melt caused by a flowing river beneath, over years or decades, would normally be spread out over a long swath of ice. This would erode a shallow channel rather than a deep cleft. But Kamb is an oddball. Around 150 years ago, it stopped moving almost entirely due to the cyclical interplay of melting and freezing at its base. It now creeps forward only about 10 meters per year. The melting is thus concentrated, year after year, in almost the same spot.
Back in 2020, all of this was still conjecture. But if Horgan and his colleagues could return, drill into the cavern and lower instruments into it, they could confirm how it formed. By studying the water, sediment and microbes flowing out of it, they could also learn a lot about Antarctica’s vast subglacial landscape.
The West Antarctic Ice Sheet covers an area three times the size of the Colorado River drainage basin, which sprawls across Arizona, Utah, Colorado and parts of four other states. To date, humans have observed only a tiny swath of this underworld, smaller than a basketball court — represented by several dozen narrow boreholes scattered across the region, where scientists have grabbed a bit of mud from the bottom or sometimes lowered in a camera.
Horgan was eager to explore more. With New Zealand already melting boreholes through ice floating on the ocean, drilling into this coastal river seemed like a natural next step.
How did the hidden cavern form? On December 4, 2021, a pair of caterpillar-tracked PistenBullys arrived at the place where Horgan and Whiteford had visited two years before. The tractors had traveled for 16 days from New Zealand’s Scott Base on the edge of the continent, growling across a thousand kilometers of floating ice as they towed a convoy of sleds packed with 90 metric tons of food, fuel and scientific gear. The convoy lumbered around to the upstream end of the valley and stopped.
Workers erected a tent the size of a small aircraft hangar, and inside it, assembled a series of water heaters, pumps and a kilometer of hose — a machine called a hot water drill. Using shovels and a small mechanized scooper, they dumped 54 tons of snow into a tank and melted it. The workers then jetted that hot water through the hose, using it to melt a narrow hole, no wider than a dinner plate, through 500 meters of ice — and down through the domed ceiling of the cavern. The sight of animals inside the cavern generated instant excitement among Horgan, Stevens and the other people at camp. But those first images were blurry, leaving people unsure of what the orange, bumblebee-sized critters actually were.
Workers next lowered an instrument down the borehole to measure the water temperature and salinity inside the cavern. They found the top 50 meters of water colder and fresher than what lay below — confirming that seawater was flowing in along the bottom and a more buoyant mixture of saltwater and freshwater was flowing out along the top. The cavern, says Stevens, “is operating quite like an estuary.”
But those measurements also presented a mystery: The water in the top of the cavern was only about 1 percent less salty than the seawater in its bottom, suggesting that the amount of freshwater flowing in through the river was “quite small,” says Stevens. It’s akin to a shallow creek that a young kid might splash around in. He and Horgan doubted that the turbulence caused by this small flow, even over 35 years, could melt the entire cavern — roughly a cubic kilometer of ice.
A likely answer came from a set of samples collected from the floor of the cavern. Gavin Dunbar, a sedimentologist at the Victoria University of Wellington, lowered a hollow plastic cylinder down the hole in hopes of retrieving a core. As he and graduate student Linda Balfoort hoisted the cylinder back up, they found it streaked and filled with chocolaty mud — a strange sight in this world of pure white, where not a speck of rock or dirt can be seen for hundreds of kilometers.
As Dunbar and Balfoort X-rayed and analyzed the cores months later, back in New Zealand, their peculiarities became obvious: They were unlike anything that Dunbar had ever encountered in this part of the world.
Every core that Dunbar had ever seen from the seafloors near this part of Antarctica consisted of a chaotic jumble of sand, silt and gravel — a material called diamict, formed as the ice sheet advances and retreats over the seafloor, plowing and mixing it like a rototiller. But in these cores, Dunbar and Balfoort saw distinct layers. Bands of coarse, gravely material were interspersed with layers of fine, silty mud.
That alternating pattern resembled samples from steep seafloor canyons off the coast of New Zealand, where earthquakes sometimes trigger underwater landslides that sweep for many kilometers downhill. Each flood deposits a single layer of chunky material.
Dunbar believes that something similar happened under the Kamb Ice Stream, possibly in the last few decades. A series of fast-moving torrents gushed through the river channel carrying big gravelly chunks from somewhere upstream that later settled on the cavern floor. “Each of these [coarse layers] represents minutes to hours of sediment deposition” that occurred during a single flood, he says. And the fine, silty layers would have been laid down over years or decades in between the floods, when the river flowed languidly along.
These subglacial floods could explain how this small river carved such a large cavern, Stevens says. Those floods could have been 100 to 1,000 times as large as the flow rates that were measured during the 2021–22 field season.
No one knows when those events happened, but scientists using satellites to study subglacial lakes have spotted at least one candidate. In 2013, a lake 20 kilometers upstream from the cavern, called KT3, disgorged an estimated 60 million cubic meters of water — enough to fill 24,000 Olympic-sized swimming pools.
Scientists would love to know whether that flood actually passed through this cavern. “Connecting this upstream to the lake system would be extremely cool,” says Matthew Siegfried, a glaciologist at the Colorado School of Mines in Golden, who coauthored one of the reports documenting the 2013 flood.
Studying the outflow of this river could also answer other questions about the subglacial landscape upstream. “The vast majority of our knowledge of subglacial lakes comes from surface observations from space,” Siegfried says. But those satellite records, of ice bobbing up and down, permit only indirect estimates of how much water is flowing through. It’s possible, for example, that a lot of water passes through the lakes even when the ice above isn’t moving.
Scientists could also learn about the subglacial landscape by studying the sediment washed downstream. When Dunbar and his colleagues examined the coarse material from their cores, they found it full of microscopic fossils: glassy shells of marine diatoms, needly spicules of sea sponges, and notched and spiky pollen grains of southern beech trees. These fossils represent the remains of a warmer world, 15 million to 20 million years ago, when a few stands of stunted, shrubby trees still clung to parts of Antarctica. Back then, the West Antarctic basin held a sea rather than an ice sheet, and this detritus settled on its muddy bottom. These old marine deposits underlie much of the West Antarctic Ice Sheet, and the few boreholes drilled so far suggest that the mix of fossils differs from one place to another. Those mixes could provide clues to how the flow of rivers changes over time.
To uncover the nuance of what’s happening in the cavern “is mind-blowingly cool,” says Christina Hulbe, a glaciologist at the University of Otago in Dunedin, New Zealand, who has studied this region of Antarctica for nearly 30 years. “That’s the outlet for a massively big river system, if you think about it.”
By studying the water, scientists could estimate the amount of organic carbon and other nutrients flowing out of the river into the ice-covered ocean. The landscape beneath the ice sheet appears to be rich in nutrients that might sustain oases of life in an otherwise famished biological desert.
Scientists unveil an oasis of life Even as the cavern penetrates farther into the Kamb Ice Stream, it does not necessarily threaten the glacier’s stability. This part of the West Antarctic coastline is not considered vulnerable, because its shallow bed shields it from the deep, warm ocean currents that are causing rapid ice loss in other regions. But subglacial rivers pour out at many other points along the coastline, including some — like Thwaites Glacier, roughly 1,100 kilometers northeast of Kamb — where the ice is retreating rapidly (SN: 3/11/23, p. 8).
Thwaites and nearby glaciers have collectively shed over 2,000 cubic kilometers of ice since 1992. They could eventually raise global sea levels by 2.3 meters if they collapse. Remote sensing studies have documented over a dozen low, squat shield volcanoes beneath this part of the ice sheet. The elevated geothermal heat flow, even from inactive volcanoes, is thought to cause high levels of melting under the ice sheet. That melting produces large amounts of subglacial water, which could render these glaciers even more vulnerable to human-caused climate change.
Horgan believes that what scientists learn at Kamb could improve our understanding of how subglacial rivers impact those other, rapidly changing coastlines of Antarctica.
But the most evocative discovery made at Kamb — in purely human terms — may be the blurry, orangish animals seen swarming near the bottom of the cavern. Stevens captured some clearer images a few days later and tentatively identified them as shrimplike marine crustaceans called amphipods. To see so many of them here, Stevens says, “we really hadn’t expected that.” Microbes like those previously found under the ice sheet in Subglacial Lake Whillans are known to eke out a living even in harsh conditions. But animals are a different matter. The deepest seafloors on Earth sit only 10 or 11 kilometers from sunlight, and animal life in those places is generally scarce. But the animals in the cavern are thriving 500 kilometers from the nearest daylight, cut off from the photosynthesis that fuels most life on Earth.
The amphipods and their supporting ecosystem must be subsisting on some other food source. But what? Observations in the Kamb ice cavern, combined with those at two other remote boreholes drilled in recent years, offer some tantalizing hints.
In 2015, researchers pierced the ice at another site 250 kilometers from the cavern, where the Whillans Ice Stream lifts off its bed and floats. In that location, a thin sliver of seawater, just 10 meters deep, sits beneath 760 meters of ice. A remotely operated vehicle, or ROV, sent down the hole captured images of fish and amphipods.
John Priscu, a microbial ecologist at Montana State University in Bozeman who was involved in the drilling at the site, believes that the glacier itself is sustaining this ecosystem. The bottom 10 meters of ice is packed with mud that had frozen onto the belly of the glacier many kilometers upstream. The mud had been dragged to its present location as the glacier oozed forward, 400 meters per year. As the ROV navigated about, bits of that muddy debris constantly rained down, released as the ice’s underside slowly melted. That debris is rich in organic matter — the rotting remains of diatoms and other phytoplankton that sank to the bottom millions of years ago when the world was warmer.
“Those amphipods are swarming to the particulate matter,” Priscu says. “They’re sensing the organic matter falling out of that basal ice.” Or perhaps they may be eating the bacteria that live on those organics.
Because the Kamb Ice Stream is barely moving, the supply of dirty ice moving toward the sea is small. But the river flowing into the ice cavern may deliver the same subglacial nutrients that are found in dirty ice. After all, the water’s journey through a series of subglacial lakes down to the river’s mouth may take years or decades. Throughout that time, the river absorbs nutrients from the organic-rich subglacial sediments.
Indeed, when scientists drilled into Subglacial Lake Whillans in 2013, they found its water honey-colored — chock-full of life-sustaining iron, ammonium and organics. “What these lakes are pumping out may be a concentrated source of nutrients” for ecosystems along the dark coastline, says Trista Vick-Majors, a microbial ecologist at Michigan Technological University in Houghton who was involved in the drilling at Lake Whillans. She has estimated that the subglacial rivers flowing out from under Kamb and its neighboring glaciers may deliver 56,000 tons of organic carbon and other nutrients to this section of the coastline every year.
More recently, in December 2019, a team from New Zealand led by Horgan and Hulbe drilled through the ice just 50 kilometers from the Kamb cavern, in a place where the Kamb Ice Stream floats on the ocean. There’s no dirty ice there and no nearby river outlets. The area resembled a famished seafloor desert; it was populated by single-celled microbes with little to eat, and few signs of animals were seen — only a few burrowing traces on the muddy bottom. Priscu sees this location as an exception that proves the point: Subglacial nutrients are the crucial energy source in this dark world under the floating ice, whether they are dragged forward on the undersides of glaciers or spilled out through subglacial rivers.
The mud and water samples collected from the Kamb ice cavern may provide a new opportunity to test that theory. Craig Cary, a microbial ecologist at the University of Waikato in New Zealand, is analyzing DNA from those samples. He hopes to determine whether the microbes in the cavern belong to taxonomic groups that are known to subsist on ammonium, methane, hydrogen or other sources of chemical energy that originate from the subglacial sediments. That might reveal whether such sources support enough microbial growth to feed the animals observed there.
The team also needs to measure the flow rate of the subglacial river that spills into the cavern, since that determines the nutrient supply. Stevens continues to monitor this thanks to a set of instruments left behind in the cavern. As people were packing up camp on January 11, 2022, workers pumped more hot water into the borehole, widening it to more than 35 centimeters — and creating a dangerous pitfall. Stevens and his colleagues donned climbing harnesses, clipped into safety ropes and approached the hole one last time. They lowered a series of cylinders the size of caulking guns down the hole. These devices continue to measure the temperature, salinity and water currents inside the cavern, sending the data 500 meters up a cable to a transmitter that beams it home via satellite once a day. That data will reveal how the river’s flow changes over time. With luck, the instruments might even detect a subglacial flood gushing through.
“That would just be outstanding,” Horgan says. For many years, he had to content himself with seeing these rivers and lakes dimly, through the outlines of water on radar and satellite images. This is “one of the first times we’ve got to stand at a river mouth and observe it.”
Spring calving season for the saiga antelope of central Kazakhstan is a delight for the researchers who keep tabs on the critically endangered animals. During the day, thousands of newborn saigas lie quiet, hidden within a sea of waving grass. Mothers return twice daily to feed them. “If you come at dawn and dusk, it’s magical,” says E.J. Milner-Gulland, a conservation biologist at the University of Oxford who has studied saigas for 27 years. “You hear this mewing noise, and all the babies come rushing up to the females.”
The sight that greeted Milner-Gulland’s colleagues in 2015, however, was horrific. Mothers and calves, behaving normally one day, suddenly became lethargic. Weakness, collapse and death soon followed. “It was like a switch was turned on in each animal,” says wildlife veterinarian Richard Kock of the Royal Veterinary College at the University of London. Mothers died first. Helpless calves, obviously distressed, tried to suckle from their dead mothers, but eventually succumbed hours later. In three short weeks, more than 200,000 carcasses littered the steppes. Even before the mystery illness, saigas (Saiga tatarica tatarica) had been under assault, their populations in steep decline from poachers who wanted their horns and meat. Habitat loss and migration-route obstructions from fences and new railways didn’t help.
Story continues after image Now, Milner-Gulland, Kock and more than a dozen Kazak and international colleagues say they’ve found the reason for this massive die-off. Based on necropsy evidence and sampling for a plethora of pathogens, the team diagnosed hemorrhagic septicemia, or fatal blood poisoning, caused by Pasteurella multocida type B bacteria, the researchers report January 17 in Science Advances. P. multocida is a normal inhabitant of the bulbous, oversized snouts of saigas. “They have it naturally in their noses, just like we all have various bacteria living harmlessly in our bodies,” Milner-Gulland says. Even newborns carry the bacteria, probably passed on from their mothers, she explains.
But higher than normal temperature and humidity, which caused the microbes to multiply, turned the bacteria deadly, according to the researchers’ statistical analysis. Milner-Gulland sees the results as a cautionary note on saigas’ future in a changing climate.
Around 107,000 saigas remain globally, Kock estimates based on a summer 2017 tally. But Milner-Gulland remains optimistic about the antelope’s future. As cofounder of the Saiga Conservation Alliance, she has a soft spot for these strange creatures, which migrate long distances, live in harsh conditions and have no evolutionarily close relatives. Plus, she says, “emotionally speaking, they are just beautiful … very unusual.”
First, a note to any impala suddenly rushed by a cheetah: Do not — repeat, do not — just zoom straight off as fast as four hooves can carry you.
The best escape move, according to analysis of the most detailed chase data yet from big cat predators, is some fluky turn, even though turning requires a slower stride. Swerve far enough, and the cheetah will be racing too fast to make the same turn. Overall, cheetahs and lions are more athletic than the impalas and zebras they chase, but prey still have a chance, says Alan Wilson of the Royal Veterinary College of the University of London in Hatfield. He and his colleagues worked with researchers in Botswana to collect abundant motion data — several hundred thousand strides’ worth — from wild animals and reconstruct their sprints and turns. “You’re actually doing a step-by-step dissection,” Wilson says, “which is pretty cool.”
Wilson, a veterinarian and research scientist who describes himself as “an equipment geek,” began collecting data in 2011 on cheetah chases (SN: 7/13/2013, p. 9). “Typically your tracking collar will tell you where an animal is once an hour, or once every five minutes if you’re lucky,” he says. Wilson and his colleagues designed collars that record data for calculating position, speed and acceleration multiple times a second. The collar falls off animals after a certain time so that researchers can retrieve it and download data on the animals’ adventures. Wilson’s team collected collar data for two predator-prey groups in Botswana’s savannah — cheetahs and impalas, and lions and zebras — though none of the collared cats were recorded chasing the collared prey. Comparing the information from more than 5,500 running episodes, the team found that each predator could outdo its typical prey by about 38 percent in speed. The predators also had about 37 percent greater acceleration and 72 percent better deceleration. Wilson and his colleagues also nipped tiny samples of muscle fiber and carried them in liquid nitrogen to England to measure muscle contraction power. Both predators had about 20 percent more fiber power in a leg muscle than the prey. To see how an impala or zebra might escape such formidable hunters, the researchers created stride-by-stride computer simulations of hypothetical pursuits. At top speeds, prey had few options for veering to where a predator couldn’t pounce. The best hope for prey came at slower speeds, when they could pivot more to the side. Lending credence to these computer results, the actual collar records showed a lot of running at merely moderate speeds by both predator and prey.
Putting numbers on the athletic powers of wild predators and prey “enables you to understand the ecosystem” Wilson says. “Your prey has to be fast enough to escape some of the time, but not all of the time. If you took lions and put them on a tropical island covered in sheep, they’d eat all the sheep — and then there’d be no lions.”
The detailed collar data allowed for an unprecedented level of analysis, says biomechanist Paolo Domenici, of the Institute for Coastal Marine Environment’s center near Oristano, Italy. Five or 10 years ago, he notes, measurements of animal athletics came mostly from treadmills or other laboratory setups without a sense of what real-world emergency might prompt particular motions.
This study “definitely adds a major piece of the puzzle in the predator-prey arms races,” Domenici says. Now “it would be interesting to test predator-prey systems in other environments to see if predators show consistently higher performance than their prey.”
But predators hunt in many more ways than pursuit, says comparative biomechanist Talia Moore of the University of Michigan in Ann Arbor, who has studied the unpredictable escape hops of little desert rodents called jerboas. She hopes the detailed look in the new paper will inspire more analysis of the diversity of predation, including animals that hunt by ambush.
Frequent fliers, take note. Scientists have figured out how cells quickly pack long chromosomes into compact, organized bundles — a key step before cells divide. The new finding unifies two competing ideas about the process: whether it involves winding chromosomes into a spiral staircase or into a set of loops. It turns out cells use two different ring-shaped proteins called condensins to do both actions, imaging and computer simulations reveal.
Normally, chromosomes sit unspooled in a cell’s nucleus. But when a cell prepares to undergo mitosis — a type of cell division — those strings of DNA must condense into easy-to-transfer cylinders. It’s a formidable task: A cell must cram about two meters of DNA into microscopic packages without tangling the genetic material like a string of holiday lights. Condensin II shapes a chromosome into large loops and then forms a helical scaffold for the loops to wind around. Condensin I subdivides large loops into smaller nested loops that allow for more space-efficient packing.
Together, the two proteins deftly stuff the chromosome into a densely packed cylinder, scientists report online January 18 in Science. Most of that condensing process happens in about 15 minutes, says study coauthor Job Dekker, a Howard Hughes Medical Institute investigator at the University of Massachusetts Medical School in Worcester.
Not all fundamental forces are created equal. An alternate universe that lacks the weak nuclear force — one of the four fundamental forces that govern all matter in our universe — could still form galaxies, stars, planets and perhaps life, according to calculations published online January 18 at arXiv.org.
Scientists have long thought that our universe wouldn’t exist, or at least wouldn’t support life, without certain physical laws. For instance, if gravity were much stronger than it is, most matter would collapse into black holes; if it were weaker, the universe wouldn’t form structures such as galaxies or planets. The strong nuclear force holds atomic nuclei together, and the electromagnetic force carries light across the universe. “Those three forces, gravity, strong and electromagnetic, are part of the deal,” says theoretical physicist Fred Adams of the University of Michigan in Ann Arbor. But the weak nuclear force — responsible for making neutrons decay into protons, electrons and neutrinos — might not be so essential (SN: 4/29/17, p. 22). “That’s the only one you can get rid of entirely without messing everything up,” he says.
A previous study had argued that a universe lacking the weak force could exist. Some physicists think our universe is just one in an infinite multiverse, where many different cosmoses exist side-by-side, possibly governed by different physical rules. We live in this one simply because we couldn’t live anywhere else (SN Online: 10/10/14), some scientists say.
“People talk about universes like they’re very fine-tuned; if you changed things just a little bit, life would die,” Adams says. But “the universe and stars have a lot more pathways to success.”
In the new research, he and his colleagues simulated how matter was created in the Big Bang and then condensed into stars, but without the effects of the weak nuclear force. In our universe, one consequence of neutron decay is that most of the universe is made of hydrogen, which consists of a single proton and electron. Stars, in their hot cores, fuse protons into helium and heavier elements and then scatter them into space, helping to create everything from planets to physicists. But with no weak force, a universe would be filled with neutrons that didn’t decay — a dead end for building heavier elements. The only way such a universe could create complex matter would be to have started out with fewer neutrons and more free protons than our universe did. That way, neutrons and protons could link up and make deuterium, also called heavy hydrogen. So Adams and his colleagues tweaked the simulated universe’s initial neutron and proton content, too.
Stars fueled with deuterium would still shine, the simulations showed, but the objects would look different. Burning deuterium is more efficient than burning hydrogen, so these stars would be a little hotter, larger and redder than our stars. But the stars could still create all the elements of the periodic table up to iron, and stellar winds could carry those elements out into space.
Any planets that formed would have water made with deuterium instead of hydrogen, which is toxic to life in our universe. “But if life had to evolve with deuterated water … it might be OK,” Adams says.
Adams and his colleagues are some of the first to explore the consequences of a “weakless” universe seriously by tweaking the numbers, says Martin Rees of the University of Cambridge, who was not involved in either study.
The paper does not help figure out if the multiverse is real, though. “We hope that eventually we’ll know,” Rees says, but “I’m not holding my breath.”
PORTLAND, Ore. — Native American fishermen in Alaska have long said that seal pups go with the wind rather than struggle against it. Now, a new study confirms that wisdom. Migrating northern fur seal pups travel hundreds of kilometers farther in blustery years than in milder years, researchers reported February 14 at the American Geophysical Union’s Ocean Sciences meeting. Those epic journeys may be linked to pup deaths.
At 4 months old, the pups are weaned and begin a voyage from the Pribilof Islands of Alaska through the Bering Sea and North Pacific Ocean that can last for 20 months before they return to the islands. Physical oceanographer Noel Pelland and colleagues compared the migrations of 168 seal pups tagged in five different years from 1996 to 2015 with winds matching the pups’ first migration years. Winds were simulated using data from the U.S. National Centers for Environmental Prediction. On average, the pups moved farther downwind when wind speeds were higher, and tended to move to the right of the wind direction — likely following wind-driven ocean currents. Tagging data lasted 130 days on average, but whether the pups died or the tags fell off is unknown. That makes it difficult to draw a definitive link to mortality, says Pelland of the National Oceanographic and Atmospheric Administration’s Alaska Fisheries Science Center in Seattle.
Still, the lengthier, more physically challenging journeys in some years may explain why populations of these northern fur seals — considered “depleted” under the Marine Mammal Protection Act — have not rebounded in recent decades despite a hunting ban.
Next the team plans to simulate seal pup migrations and compare those modeled journeys with decades of wind records. Hunting records from the mid-20th century include data on seal mortality, Pelland says; comparing these data might help identify a direct link between winds and pup deaths.
Neandertals drew on cave walls and made personal ornaments long before encountering Homo sapiens, two new studies find. These discoveries paint bulky, jut-jawed Neandertals as the mental equals of ancient humans, scientists say.
Rock art depicting abstract shapes and hand stencils in three Spanish caves dates back to at least 64,800 years ago, researchers report in the Feb. 23 Science. If these new estimates hold up, the Spanish finds become the world’s oldest known examples of cave art, preceding evidence of humans’ arrival in Europe by at least 20,000 years (SN Online: 11/2/11). The finds raise the possibility that “Neandertals took modern humans into caves and showed them how to paint,” says archaeologist Francesco d’Errico of the University of Bordeaux in France.
Personal ornaments previously found at a coastal cave in southeastern Spain are older than the cave art, dating to around 120,000 to 115,000 years ago, scientists report February 22 in Science Advances. Only Neandertals inhabited Europe at that time. Those artifacts consist of pigment-stained seashells with artificial holes, presumably for use as necklaces, and seashells containing remnants of pigment mixtures, say geochronologist Dirk Hoffmann of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues. Hoffmann is also an author of the cave art study. The new findings join previous reports of potentially symbolic Neandertal artifacts, such as a possible necklace made from eagle claws (SN: 4/18/15, p. 7) and bird-feather decorations. If Neandertals did have the capacity for symbolic thinking — crucial for using drawings or language to represent ideas and objects — that ability may have developed at least 500,000 years ago in an ancestor shared with humans, the two research teams propose. “Neandertal social life was as complex as that of [contemporaneous] humans in Africa,” says archaeologist João Zilhão of the University of Barcelona, an author of both papers.
But some scientists view the new findings cautiously. Neandertals communicated in sophisticated ways, but few clearly symbolic artifacts have been linked to them, says archaeologist Nicholas Conard of the University of Tübingen in Germany. “If Neandertals regularly produced paintings or similar kinds of symbolic artifacts, researchers will eventually demonstrate it at multiple sites,” he says.
Analyses of thin mineral deposits partly covering painted cave areas provided minimum age estimates for the art, based on known decay rates of radioactive uranium in the rock. One red, rectangular painting dates to at least 64,800 years ago. One of several hand stencils in a second cave dates to at least 66,700 years ago. And in a third cave, patches of red paint were applied to the walls at least 65,500 years ago, with more paintings added over a period of 25,000 years or more — signaling a long Neandertal tradition of cave art, the researchers say. Many dated deposits at the Spanish cave art sites contain rock particles from external sources that can throw off age estimates. The researchers statistically corrected for such contamination, “but whether that is sufficient enough remains to be seen,” says archaeologist Katerina Douka of the Max Planck Institute for the Science of Human History in Jena, Germany.
At the coastal cave, dating relied on a one-two punch: uranium analyses of rock partly covering shell-bearing sediment and geologic estimates of when ancient sea levels declined enough to allow entry into the chamber.
Still, it is “nearly impossible” to generate accurate age estimates of rock art based on uranium measures alone, researchers concluded in 2017 in Quaternary International. Depending on shifting cave conditions and varying amounts of uranium drainage from mineral deposits, this method can over- or underestimate when rock art was created, the scientists argued. Other researchers defend this technique as providing valuable minimum and maximum age estimates for rock art.
If the new dates for the Spanish cave art are confirmed, they could indicate that Neandertals and H. sapiens exchanged artistic traditions earlier than previously thought, says paleoanthropologist Chris Stringer of the Natural History Museum in London, who was not involved in the studies. Members of both species may have reached western Asia and intermingled during rainy periods between 244,000 and 190,000 years ago, Stringer proposes (SN: 2/17/18, p. 6).
