A newfound species of frog doesn’t ribbit. In fact, it doesn’t make any sound at all.
Many frogs have unusual characteristics, from turning translucent to being clumsy jumpers ( SN: 12/22/22; 6/15/22). The recently discovered amphibian lacks a voice. It joins a group of seven other voiceless frog species called spiny-throated reed frogs that reside in East Africa.
Instead of croaking, the spines on male frogs’ throats might help their female counterparts recognize potential mates via touch, sort of like braille, says conservation biologist Lucinda Lawson of the University of Cincinnati.
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Lawson and colleagues spotted the little frog, only about 25 millimeters long, in 2019 while surveying wildlife in Tanzania’s Ukaguru Mountains. The team immediately recognized the animal, now named Hyperolius ukaguruensis , as a spiny-throated reed frog. But something seemed off.
“It [was] the wrong color,” Lawson says. Most frogs from this group are green and silver, but this one was gold and brown. Some quick measurements to check if the peculiar frog simply had trivial color variations or if it could be a new species revealed that its eyes were smaller than other spiny-throated reed frogs. The researchers agreed: “Let’s do some genetics,” Lawson says.
They ran DNA tests on two frogs that looked like they belonged to the suspected new species, as well as 10 individuals belonging to known spiny-throated species. Comparing the golden frogs’ genetic makeup with that of the others revealed the oddballs were genetically distinct , Lawson and colleagues report February 2 in PLOS ONE .
Each frog species in this voiceless group — including H. ukaguruensis — lives in its own isolated domain of forest. All seven of the previously known species are endangered or vulnerable. This seclusion makes it vital to distinguish species and get them added to the conservation priority list, Lawson says. Then, governments and organizations can begin protecting the region that the new, potentially endangered animal calls home.
McKenzie Prillaman is the Spring 2023 science writing intern at Science News . She holds a bachelor’s degree in neuroscience with a minor in bioethics from the University of Virginia and a master’s degree in science communication from the University of California, Santa Cruz.
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Scientists created a new form of ice by shaking 1-centimeter-wide stainless steel balls together with standard ice (shown) at low temperature. The new ice has a density close to commonplace liquid water.
Ice cubes float in water because they’re less dense than the liquid. But a newfound type of ice has a density nearly equal to what’s in your water glass , researchers report in the Feb. 3 Science . If you could plop this ice in your cup without it melting immediately, it would bob around, neither floating nor sinking.
The new ice is a special type called an amorphous ice. That means the water molecules within it aren’t arranged in a neat pattern, as in normal, crystalline ice. Other types of amorphous ice are already known, but they have densities either lower or higher than water’s density under standard conditions. Some scientists hope this newly made amorphous ice could help solve the scientific mysteries that swirl around water.
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To generate the new ice, scientists used a surprisingly simple technique. Called ball milling, it involves shaking a container of ice and stainless steel balls, cooled to 77 kelvins (nearly –200° Celsius). The researchers were motivated by curiosity; they didn’t expect the technique to produce a new amorphous ice. “It was a sort of Friday-afternoon idea we had, to just give it a go and see what happens,” says physical chemist Christoph Salzmann of University College London.
An analysis of how X-rays scattered from the frosty stuff suggested they’d created an amorphous ice. And computer simulations that mimicked the effects of ball milling revealed that a disordered structure could be produced by layers of ice sliding past one another in random directions, in response to the forces exerted by the balls.
“You have to be open, as a scientist, for the unexpected,” says chemical physicist Anders Nilsson of Stockholm University, who was not involved with the research. The ball milling technique, he says, “was quite innovative to do.”
Since the material was made by mashing up normal ice, its relationship to liquid water is unknown. It’s unclear whether it can be produced directly, by cooling liquid water. Not all amorphous ices share this connection with their liquid state.
If the new ice does have this link to the liquid, the ice might help scientists better understand water’s quirks. Water is puzzling because it flouts the norms for liquids. For example, whereas most liquids become denser upon cooling, water gets denser as it gets closer to 4° C, but becomes less dense as it is cooled further.
Many scientists suspect water’s weirdness is connected to its behavior as a supercooled liquid ( SN: 9/28/20 ). Pure water can remain a liquid at temperatures well below freezing. Under such conditions, liquid water is thought to exist in two different phases , a high-density liquid and a low-density one, and that dual nature could explain water’s behavior under more typical conditions ( SN: 11/19/20 ). But much remains uncertain about that idea.
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Salzmann and colleagues suggest that the new ice could be a special form of water called a glass. Glasses can be made by cooling a liquid quickly enough that the molecules can’t rearrange into a crystal structure. The glass in a windowpane is an example of this kind of material, made by cooling molten silica sand, but other substances can form glasses, too.
If the new ice is a glass state of water, scientists would need to work out how it fits into that dual-liquid picture. And that could help scientists tease out what’s really going on at difficult-to-study supercooled conditions.
But some researchers are skeptical that the new material has any connection to the weird physics of liquid water. Physical chemist Thomas Loerting of the University of Innsbruck in Austria thinks that the ice is “closely related to very small, distorted ice crystals,” rather than the liquid form of water.
Still, earlier computer simulations have suggested that water could form glasses of a range of densities close to liquid water, says computational physicist Nicolas Giovambattista of Brooklyn College of the City University of New York. Those simulations produced structures similar to the ones seen in the computer simulation of ball milling ice, says Giovambattista, who was not involved with the new research. “It opens doors for new questions. It’s new, so what is it?”
A. Rosu-Finsen et al. Medium-density amorphous ice . Science . Vol. 379, February 3, 2023, p. 474. doi: 10.1126/science.abq2105.
Physics writer Emily Conover has a Ph.D. in physics from the University of Chicago. She is a two-time winner of the D.C. Science Writers’ Association Newsbrief award.
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Human footprints (shown) in modern-day New Mexico may be more than 20,000 years old. If so, that would offer some of the best evidence yet that people arrived in North America by the peak of the last ice age.
DAVID BUSTOS/NATIONAL PARK SERVICE, BOURNEMOUTH UNIV.
Early man in America takes a step backward — Science News , January 27, 1973
“Early Americans lived among and hunted mammoth, camel, extinct horse and bison as far back as 15,000 years. Now there is mounting evidence for a second breakthrough that will push the history of man in America back to 30,000 years — and possibly further.”
The question of when humans first set foot in the Americas is still hotly debated. Recent fossil and archaeological evidence suggests the first inhabitants arrived tens of thousands of years ago. For instance, humanlike footprints in New Mexico date to about 20,000 years ago ( SN: 11/6/21, p. 12 ). And stone tools found in a cave hint that humans resided in Mexico roughly 30,000 years ago ( SN: 7/3/21 & 7/17/21, p. 16 ). Some archaeologists argue that stones caked with mastodon bone residue that were found in California were tools used by humans or their close relatives around 130,000 years ago, although that claim remains controversial ( SN Online: 12/4/20 ). Pinning down the timeline of human settlement could reveal how people spread across North and South America.
Previously the staff writer for physical sciences at Science News , Maria Temming is the assistant editor at Science News Explores . She has bachelor’s degrees in physics and English, and a master’s in science writing.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education (EIN 53-0196483).
A plant’s version of muscles does the lifting and pushing that shuts a Mimosa pudica plant leaf like a book when touched, perhaps as defense against danger. Now scientists are looking at how structural details of the musclelike cells enhance the plant’s folding abilities.
Call them plant motors. Or plant muscles. Tiny bulges of specialized cells in a mimosa plant can fold its feathery leaflets together in seconds, then relax — and do it again.
A new look at these bulges on the Mimosa pudica plant has revealed more details of how a leaf manages its unusually fast folding, says biomechanist David Sleboda of the University of California, Irvine. “I think that these particular organs are really cool because their motion is reversible,” he says. “[W]hen people see plant motion that is reversible, it feels much more similar to animal motion.”
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Scientists have already worked out the basic chemistry that drives a little mimosa motor , or pulvinus, he and colleagues write in a paper slated for the Feb. 6 Current Biology . When a deer hoof or something else scary jostles a leaf, potassium and some other ions shift from one part of a pulvinus toward another. Water follows the swoosh of ions. Cells that lose water deflate and sag while those on the other side bloat. Distortions in multiple pulvini make the halves of a feathery leaf fold toward each other, like an invisible hand gently closing a book.
Instead of studying chemistry, Sleboda and colleagues looked at microscopic structural details in pulvinus cells that help create such useful distortions, he reported January 7 at the annual meeting of the Society for Integrative and Comparative Biology in Austin, Texas. One feature that makes plant-muscle cells bloat more efficiently is reinforcement with microscopic fibrils. They work like corsets, keeping cells from bulging out in all directions. Instead, the corset directs much of the swelling along the axis that will fold up the leaf halves.
Also, pulvinus cells that need to bulge fast have what look like wrinkles of easily expandable tissue for inrushing water, plus special highly porous zones called pit fields. The pits look as if water could sluice through easily in a tickled-leaf emergency. Cell arrangement itself looks specialized for expanding and shrinking. A pulvinus cross section reveals a pattern “like the bellows of a concertina,” Sleboda said.
The widespread M. pudica , or sensitive plant, is one of the better-known leaf flexors. Yet clusters of other plants in the same family, the legumes, also move their leaves, says botanist Thainara Policarpo Mendes of Universidade Estadual Paulista in Botucatu, Brazil. Some relatives close fast like M. pudica , but many are slower. What she also thinks about, though, is why leaves close at all. People have proposed a variety of advantages: discouraging animals from grazing on a plant that suddenly looks more sticklike, or even helping a plant lose less heat on very cold nights.
Sleboda too can reel off proposed hypotheses but remains skeptical of all of them. “There’s not a ton of research,” he says. That, however, is fine with him. “My favorite thing about sensitive plants’ leaf closing,” he says, “is that we don’t know why they do it.”
Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.
Our mission is to provide accurate, engaging news of science to the public. That mission has never been more important than it is today.
As a nonprofit news organization, we cannot do it without you.
Your support enables us to keep our content free and accessible to the next generation of scientists and engineers. Invest in quality science journalism by donating today.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education (EIN 53-0196483).
We’ve all heard that dogs are a man’s best friend, but our canine companions don’t make up the entirety of humankind’s friend circle. Humans have cooperated with wild animals throughout our evolutionary history, forming reciprocally beneficial relationships known to biologists as mutualisms.
One particularly piscine partnership that made headlines recently can be found in Brazil, where fishers catch nets full of fish with the aid of the local bottlenosed dolphin ( Tursiops truncatus gephyreus ).
This team-up started over a century ago, probably when fishers first noticed that the presence of dolphins was a clue that fish were hiding in the murky water, says Mauricio Cantor, a behavioral ecologist at Oregon State University’s Marine Mammal Institute in Newport.
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“The dolphins are really good at detecting fish and herding them toward the coast,” he says, “and the fishers are really good at trapping the fish with their net.” Once the fish are mostly secured in the net, the dolphins are sure to snag a few for themselves.
In a study published January 30 in the Proceedings of the National Academy of Sciences , Cantor and colleagues used long-term data to show that the dolphins and fishers respond to cues from the other , and without experienced partners who know the right dance steps, the routine falls apart. “This is a really remarkable and impressive study,” says Pat Shipman, an anthropologist at Penn State University who was not involved with the research.
This fishing partnership is an important part of the cultural identity of both the fishers and the dolphins, but Cantor and his colleagues’ work shows that the practice is in decline . And among human-animal partnerships, it’s not alone. “Most of the historical cases are declining or already gone,” Cantor says.
Given their rarity and charm, let’s take a look at some of the other known examples of human-animal cooperation.
The bottlenosed isn’t the only dolphin that humans have formed beneficial arrangements with. In the 1800s, several hunters began working with a pod of orcas ( Orcinus orca ) to catch large whales. At Twofold Bay in southeastern Australia, some orcas would find and harass a whale to tire it out, while others swam to alert whaling crews (made up of Aboriginal Australians and Scottish immigrants) that they’d found prey.
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Once the whalers arrived and harpooned the whale, they let the orcas eat the tongue — a delicacy in the killer whale culinary world — before taking the rest for themselves.
While the dolphins and fishers in Brazil were chasing the same prey — schools of migratory mullet ( Mugil liza ) — the orcas and whalers were mostly after different things. The key similarity, Cantor says, is that there’s enough prey for everyone, so that no competition arises to spoil the partnership.
This relationship ultimately ended when some settlers killed two orcas, which drove the cooperative pod away from the bay, seemingly never to hunt with humans again.
Sometimes, a name says it all. Such is the case for the greater honeyguide ( Indicator indicator ), which has been labeled in both English and Latin based on its most famous trait. These birds live in sub-Saharan Africa, and cooperate with local honey hunters to gain access to succulent beeswax ( SN: 7/21/16 ).
Birds, like humans, don’t like to be stung by bees, so a honeyguide that’s hankering for beeswax will chirp at a person to signal that they should follow. The honeyguide then leads the hunters to a bee nest and lets them do the dirty work of harvesting it.
Like with orcas, honeyguides and humans are after different parts of the prize: Humans want the honey, while the birds want the wax. Honeyguides are so helpful for finding bee nests that the Borana people of East Africa blow a special whistle called a “fuulido ” to summon them when it’s time for a honey hunt.
Similar to the dolphins in Brazil, the relationship with honeyguides is an important part of many African cultures. Legend even has it that a scorned honeyguide, if denied beeswax on prior hunts, will lead the hunters not to delicious honey but instead into the jaws of a dangerous predator, like a lion.
To see the most extreme outcome of human-animal partnership, take a look at 39 percent of the country’s beds, couches and backyards. That’s about how many households in the United States own a dog. But it turns out a canine doesn’t have to be domesticated to get along with humans; Indigenous stories from peoples in North America describe cooperating with gray wolves ( Canis lupus ) to hunt big game like elk and mammoths.
The wolves would run down the prey until it tired, and humans would make the kill once they caught up. Because these prey items were so massive (like the large schools of mullet), it didn’t matter that humans and wolves were after the same thing — there was plenty to go around.
Though this furry friendship doesn’t exist anymore, wolves are still important in many Indigenous cultures. Some even still continue the practice of leaving some meat for the wolves after a hunt.
Though human-animal partnerships are rare and on the decline, they “give us an illustration of how positive our human interactions can be with nature,” Cantor says.
For Shipman, the urge to engage with other animals is a defining trait of humanity. “It’s in some ways as fundamental to humans,” she says, “as being bipedal.”
Our mission is to provide accurate, engaging news of science to the public. That mission has never been more important than it is today.
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Your support enables us to keep our content free and accessible to the next generation of scientists and engineers. Invest in quality science journalism by donating today.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education (EIN 53-0196483).
The Arctic today is a hostile place for most primates. But a series of fossils found since the 1970s suggest that wasn’t always the case.
Dozens of fossilized teeth and jaw bones unearthed in northern Canada belonged to two species of early primates — or at least close relatives of primates — that lived in the Arctic around 52 million years ago, researchers report January 25 in PLOS ONE . These remains are the first primate-like fossils ever discovered in the Arctic and tell of a groundhog-sized animal that may have skittered across trees in a swamp that once existed above the Arctic Circle.
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The Arctic was significantly warmer during that time. But creatures still had to adapt to extreme conditions such as long winter months without sunlight. These challenges make the presence of primate-like creatures in the Arctic “incredibly surprising,” says coauthor Chris Beard, a paleontologist at the University of Kansas in Lawrence. “No other primate or primate relative has ever been found this far north so far.”
Between frigid temperatures, limited plant growth and months of perpetual darkness, living in the modern Arctic isn’t easy. This is especially true for primates, which evolved from small, tree-dwelling creatures that largely fed on fruit ( SN: 6/5/13 ). To this day, most primates — humans and few other outliers like Japan’s snow monkeys excepted — tend to stick to tropical and subtropical forests, largely found around the equator.
But these forests haven’t always been confined to their present location. During the early Eocene Epoch, which started around 56 million years ago, the planet underwent a period of intense warming that allowed forests and their warm-loving residents to expand northward ( SN: 11/3/15 ).
Scientists know about this early Arctic climate in part because of decades of paleontological work on Ellesmere Island in northern Canada. These digs revealed that the area was once dominated by swamps not unlike those found in the southeastern United States today. This ancient, warm, wet Arctic environment was home to a wide array of heat-loving animals, including giant tapirs and crocodile relatives.
For the new study, Beard and his colleagues examined dozens of teeth and jawbone fossils found in the area, concluding that they belong to two species, Ignacius mckennai and Ignacius dawsonae . These two species belonged to a now-extinct genus of small mammals that was widespread across North America during the Eocene. The Arctic variants probably made their way north as the planet warmed, taking advantage of the new habitat opening up near the poles.
Scientists have long debated whether this lineage can be considered true primates or whether they were simply close relatives. Regardless, it’s still “really weird and unexpected” to find primates or their relatives in the area, says Mary Silcox, a vertebrate paleontologist at the University of Toronto Scarborough.
For one thing, Ellesmere Island was already north of the Arctic Circle 52 million years ago. So while conditions may have been warmer and wetter, the swamp was plunged into continuous darkness during the winter months.
Newly arrived Ignacius would have had to adapt to these conditions. Unlike their southern kin, the Arctic Ignacius had unusually strong jaws and teeth suited to eating hard foods, the researchers found. This may have helped these early primates feed on nuts and seeds over the winter, when fruit wasn’t as readily available.
This research can shed light on how animals can adapt to live in extreme conditions. “Ellesmere Island is arguably the best deep time analog for a mild, ice-free Arctic,” says Jaelyn Eberle, a vertebrate paleontologist at the University of Colorado Boulder.
Studying how plants and animals adapted to this remarkable period in Arctic history, Beard says, could offer clues to the Arctic’s future residents.
Freda Kreier was a fall 2021 intern at Science News . She holds a bachelor’s degree in molecular biology from Colorado College and a master’s in science communication from the University of California, Santa Cruz.
Our mission is to provide accurate, engaging news of science to the public. That mission has never been more important than it is today.
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Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education (EIN 53-0196483).
