Life on Earth may have begun as dividing droplets

NEW ORLEANS — In a primordial soup on ancient Earth, droplets of chemicals may have paved the way for the first cells. Shape-shifting droplets split, grow and split again in new computer simulations. The result indicates that simple chemical blobs can exhibit replication, one of the most basic properties of life, physicist Rabea Seyboldt of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, reported March 16 at a meeting of the American Physical Society.

Within a liquid, small droplets of particular chemicals can separate out, like beads of oil in water. Such globules typically remain spherical, growing as they merge with other drops. But in simulations, Seyboldt and colleagues found that droplets might behave in a counterintuitive way under certain conditions, elongating and eventually dividing into two.
If additional droplet material is continuously produced in reactions in the primordial soup, chemicals will accumulate on either end of a droplet, causing it to elongate, the simulations show. Meanwhile, waste products from the droplet are eliminated from the middle, causing the droplet to pinch in and eventually split. The resulting pair of droplets would then grow and split again to create a new generation. In addition to the above reactions, the process requires an energy source, such as heat or chemicals from a hydrothermal vent, to get reactions going.

The study, which was also described in Nature Physics in December, is theoretical — the researchers didn’t select particular chemicals for study but simply showed that certain types of reactions could cause droplets to split.

How such droplets would have evolved into vastly more complicated cells is unknown. “This is really a minimal scenario that’s supposed to give the very first indications of something that goes towards life, but if you look at living cells today, they’re infinitely more complex,” Seyboldt said.

Camera trap catches a badger burying a cow

The American badger is known to cache carrion in the ground. The animals squirrel away future meals underground, which acts something like a natural refrigerator, keeping their food cool and hidden from anything that might want to steal it. Researchers, though, had never spotted badgers burying anything bigger than a jackrabbit — until 2016, when a young, dead cow went missing in a study of scavengers in northwestern Utah.

That January, University of Utah researchers had set out seven calves (all of which had died from natural causes) weighing 18 to 27 kilograms in the Great Basin Desert, each monitored by a camera trap. After a week, one of the carcasses went missing, even though it, like the others, had been staked in place so nothing could drag it off. But perhaps a coyote or mountain lion managed the feat, the researchers thought.

Then they checked the camera. What they found surprised them.

The images showed a badger happening upon the calf on January 16. The next evening, the badger returned and spent four hours digging below and around the bovine, breaking for only five minutes to snack on its find. It came back and continued digging the next afternoon and the following morning, by which time the calf had fallen into the crater the badger had dug. But that wasn’t the end. The badger then spent a couple more days backfilling the hole, covering its find and leaving itself a small entrance.
The badger stayed with his meal for the next couple of weeks, venturing out briefly from time to time. (It’s impossible to know where the badger went, but getting a drink is one possibility, says the study’s lead author Ethan Frehner.) By late February, the badger was still visiting its find from time to time. But herds of (living) cows kept coming through the site, and though the badger checked on its cache several times, it never re-entered the burrow after March 6.

It turns out that this badger was not alone in taking advantage of the research project for a huge, free meal. Simultaneously at one of the other carcass sites about three kilometers away, another badger attempted to bury a calf that had been staked out there. It only got the job partway done, though, as the anchoring stake prevented the badger from finishing a full burial. Instead, the badger dug itself a hole and spent several weeks there, periodically feeding on its find.
This is the first time scientists have documented American badgers burying a carcass so much bigger than themselves (the calves were three to four times the weight of the badgers), the team reports March 31 in Western North American Naturalist.

“All scavengers play an important ecological role — helping to recycle nutrients and to remove carrion and disease vectors from the ecosystem,” Frehner says. “The fact that American badgers could bury carcasses of this size indicates that they could potentially bury the majority of the carrion that they would come into contact with in the wild. If they exhibit this behavior across their range, the American badger could be accounting for a significant amount of the scavenging and decomposition process which occurs throughout a large area in western North America.”

And that burial may have a benefit for ranchers, the researchers note: If badgers bury calves that have died of disease, that may reduce the likelihood that a disease will spread. It’s too soon to say whether that happens, but study co-author Evan Buechley notes, “that merits further study.”

Frog slime protein fights off the flu

The next flu drug could come from frog mucus. It’s not as crazy as it sounds: For decades, scientists have searched for new antiviral drugs by mining proteins that animals produce to protect themselves from microbes. In lab tests, proteins found in amphibian secretions can defend against HIV, herpes and now the flu.

David Holthausen of Emory University in Atlanta and colleagues sampled slime from the skin of Hydrophylax bahuvistara, a recently discovered frog species from southern India. They tested the influenza-fighting ability of 32 slime peptides. Four showed promise, but three proved toxic to mammals.
The fourth peptide, however, was safe and showed a propensity for fighting off the flu. When exposed to four H3N2 and eight H1N1 strains, this peptide, dubbed urumin, inhibited H3N2 viruses to a degree but was particularly adept at killing H1N1 viruses, which are more common among humans. The frog slime protein even cut viral numbers in a set of seven drug-resistant strains and protected mice during flu infections. Urumin blows up flu virus particles by targeting the stalk region of the hemagglutinin protein in H1 varieties, the team found. With further development, urumin could form the basis of future influenza drugs, the researchers write in the April 18 Immunity.

Stunning images reveal glacial landscapes under the oceans

The footprints of long-gone glaciers and icebergs are now frozen in time in a stunning new collection of images of Earth’s seafloor.

The Atlas of Submarine Glacial Landforms is a comprehensive, high-resolution atlas of underwater landscapes that have been shaped by glaciers, largely in polar and subpolar regions, and provides a comparative look at how glaciers, ice and related climate shifts transform Earth. Kelly Hogan, a marine geophysicist with the British Antarctic Survey and an editor of the atlas, presented it April 26 in Vienna at a meeting of the European Geosciences Union.
Most of the more than 200 images were generated from research vessels using multibeam bathymetry, which renders the seafloor surface in 3-D, exposing a region’s glacial history. For example, the distinctive asymmetry of 20,000-year-old glacial deposits called drumlins in the Gulf of Bothnia, between Finland and Sweden, suggests that ice flowed south, toward a larger glacier in the Baltic Sea.

Other images reveal the tracks of icebergs that once plowed and scribbled the ocean floor, such as those seen in the Barents Sea in the Arctic Ocean. The tracks may look random, but they tell tales of past currents and water depth.

In all, the seafloor depicted in the atlas covers an area about the size of Great Britain. But the real impact of the project goes beyond individual images, Hogan says. She expects that scholars exploring glacial history, researchers predicting future ice behavior and climate scientists are among those who will keep a copy close at hand.

For humans, the appeal of looking at faces starts before birth

Fascination with faces is nature, not nurture, suggests a new study of third-trimester fetuses.

Scientists have long known that babies like looking at faces more than other objects. But research published online June 8 in Current Biology offers evidence that this preference develops before birth. In the first-ever study of prenatal visual perception, fetuses were more likely to move their heads to track facelike configurations of light projected into the womb than nonfacelike shapes.

Past research has shown that newborns pay special attention to faces, even if a “face” is stripped down to its bare essentials — for instance, a triangle of three dots: two up top for eyes, one below for a mouth or nose. This preoccupation with faces is considered crucial to social development.
“The basic tendency to pick out a face as being different from other things in your environment, and then to actually look at it, is the first step to learning who the important people are in your world,” says Scott Johnson, a developmental psychologist at UCLA who was not involved in the study.

Using a 4-D ultrasound, the researchers watched how 34-week-old fetuses reacted to seeing facelike triangles compared with seeing triangles with one dot above and two below. They projected triangles of red light in both configurations through a mother’s abdomen into the fetus’s peripheral vision. Then, they slid the light across the mom’s belly, away from the fetus’s line of sight, to see if it would turn its head to continue looking at the image.
The researchers showed 39 fetuses each type of triangle five times. Of the 195 times a facelike triangle was projected, fetuses turned their heads 40 times. In contrast, the nonfacelike triangles elicited only 14 head turns, says study coauthor Vincent Reid of Lancaster University in England. The finding suggests that fetuses share newborns’ predisposition for looking at facelike shapes, the researchers conclude.
Psychologist Melanie Spence of the University of Texas at Dallas, who was not involved in the work, says it’s a leap to draw too many similarities between the visual perceptions of fetuses and newborns. Although the triangle images mimic facelike ones used to test newborns, they aren’t the same, she notes. Scientists typically show babies faces in black and white, with head-shaped borders.

Still, Johnson says evidence that a fundamental aspect of facial perception may be hardwired into humans’ visual system is “very, very exciting.” The new study’s method of projecting images into the womb and watching the fetus’s reaction also “opens up all kinds of new doors to understand human development,” Johnson says. A similar light projection and 4-D ultrasound technique might be used to see whether fetuses can distinguish between different quantities in the same way that babies can.

A baby’s DNA may kick off mom’s preeclampsia

A protein made by the fetus may lead to preeclampsia in moms.

People born to mothers who had the prenatal disorder were more likely to have certain DNA variations near a gene known to influence blood vessels. The results, published online June 19 in Nature Genetics, point to that gene as a possible preeclampsia culprit, and may help scientists develop ways to stop or prevent the pregnancy complication. Preeclampsia, which is marked by a dangerous spike in blood pressure, affects about 5 percent of pregnancies and is estimated to kill over 70,000 women a year globally.
Scientists have known that preeclampsia can run in families, but the genetics of the fetus hadn’t been scrutinized. “Over the years, people have looked at mothers’ genes,” says geneticist Linda Morgan of the University of Nottingham in England. “This is the first large study to look at babies’ genes.”

Morgan and colleagues compared DNA variations in 2,658 babies, children and adults born to mothers who had preeclampsia with those in more than 300,000 people. (This large group probably included some people born to mothers with the condition, but the vast majority were not.)

A genome-wide association study (GWAS), a technique used to comb through DNA looking for genetic variations that may be linked to a disorder, pinpointed a spot on chromosome 13, near a gene called FLT1. That gene is involved with blood vessel formation, an intricate process for the placenta as it grows into the inside wall of the uterus and merges the baby’s blood supply to the mother’s. The same genetic hot spot turned up in tests of a second group of offspring from mothers who had preeclampsia, Morgan and colleagues report. Another DNA variation near the gene also showed a link to the disorder.

Identifying FLT1 “makes a lot of sense,” says Ananth Karumanchi, a vascular biologist at Beth Israel Deaconess Medical Center in Boston, who was not involved in the study. Earlier experiments by Karumanchi and others suggest that the gene plays a role in preeclampsia.

Preeclampsia is kicked off by the placenta, an organ grown mostly from fetal cells that helps provide nutrients to the fetus. And though the details are unclear, some scientists suspect that unhealthy placentas start to pump out too much Flt-1 protein. A version of the protein called sFlt-1 can then slip into a mother’s bloodstream, where it may damage blood vessels in a way that leads to high blood pressure.
The GWAS results can’t explain the bulk of preeclampsia cases. A fetus carrying a single copy of one of the troublesome variants near FLT1 raised a mother’s risk of preeclampsia by about 20 percent, the analysis suggests. Other risk factors are known to be much stronger, Morgan says, including previous high blood pressure, former preeclampsia diagnoses or carrying twins.

Karumanchi says that the genetic results might not be strong enough on their own to make the case that the gene is involved. But other work points to FLT1. “We feel it’s the right target,” he says.

In Europe, a preliminary clinical trial is testing a filtration method that removes excess sFlt-1 protein from the blood of women with signs of preeclampsia. So far, about 20 women have undergone the procedure, says nephrologist Ravi Thadhani of Massachusetts General Hospital in Boston. Early results are “quite encouraging,” he says, and he hopes to expand the study soon.

50 years ago, diabetic mice offered hope for understanding human disease

[Millions of diabetics] could be indebted to a strain of diabetic mice being bred in Bar Harbor, Maine. In diabetes research, “this mouse is the best working model to date,” one of its discoverers, Dr. Katharine P. Hummel, says.… A satisfactory animal subject had eluded diabetes researchers, until the mouse was found. — Science News, August 12, 1967

Update
Hummel’s diabetic mice are still used in research to mimic type 2 diabetes in humans, which is linked to obesity. In the mid-1990s, researchers found that the diabetic mice carry a mutation in the leptin receptor gene, which prevents the hormone leptin from signaling fullness and triggering other metabolic processes. In people, however, the disease is more complicated. More than 40 genetic variants are associated with susceptibility to type 2 diabetes. Unlike the mouse mutation, none of those variants guarantee a person will develop the disease.

Climate change is shifting when Europe’s rivers flood

Across Europe, rivers aren’t flooding when they used to.

Long-term changes in temperature and precipitation are making some rivers flood days, weeks or even months earlier than they did 50 years ago, and pushing flooding in other areas much later, researchers report August 11 in Science. Those changes could impact people, wildlife and farms near rivers.

Previous studies have shown that climate change is likely to increase the severity and frequency of coastal floods, but it can be tricky to concretely link river flooding to climate change, says Günter Blöschl, a hydrologist at the Vienna University of Technology who led the study.
Coastal flooding is worsened largely by one overriding variable that can be tracked: sea level rise. But river flooding is affected by a complex set of factors, says Rob Moore, a policy analyst at the Natural Resources Defense Council in Chicago who specializes in water issues. Both the timing and quantity of precipitation matter, as does the type of soil and whether it’s dry or already waterlogged when rain hits. What’s more, changes in land use around a river or engineering projects such as dams that change river flow can also affect flood risk — but aren’t necessarily related to the climate.
So instead of tracking the size or frequency of river floods, the researchers examined the seasonal timing of those floods. That measurement is less impacted by factors that have nothing to do with climate. Blöschl worked with researchers from 38 countries to analyze hydrological data collected at 4,262 sites across Europe from 1960 to 2010.

Flood season shifted as much as 13 days earlier or nine days later per decade, the researchers found. Over the entire study period, that shift added up to floods in some regions occurring, in the most extreme cases, as much as 65 days earlier or 45 days later. The biggest changes were in Western Europe, where a quarter of the monitoring sites recorded flood timing shifts of more than 36 days over the 50-year period. Elsewhere, effects were more moderate, though still measurable: In northeastern Europe and the area around the North Sea, for instance, more than half of the stations showed shifts of more than 8 days.
The effect varies substantially by region because not all parts of Europe experience the same sorts of floods, says Blöschl. In southern Sweden and the Baltics, floods are mostly driven by snowmelt. Warmer local temperatures make the snow melt earlier in the spring, shifting flood season up, too. In southern England, on the other hand, heavy autumn rains saturate the soil, and subsequent winter deluges can cause flooding. Flood season there is driven by when the soil gets too waterlogged to take in more moisture.

The study shows that flood timing has changed, but does not address specific consequences. It’s clear, though, that off-season flooding could have far-reaching effects, especially if these trends continue. Animals that rely on river conditions at a certain time of year in order to breed or find food could be affected by surprise floods. Out-of-season floods or unexpected dry spells could damage crops.

Plus, people are less prepared when big floods happen off-season, says Moore. While a comprehensive study like this one hasn’t been done in the United States, floods are occurring at unusual times here, too, he notes. Moore cites devastating floods that swelled the upper Mississippi River to a record size in December 2015 — not the time of year when the river is expected to overflow its banks. That flooding, combined with tornadoes spurred by the same storm system, killed more than 50 people and caused almost $2 billion in damage.

Today is the day! A last-minute guide for watching the Great American Eclipse

Just a stab in the dark, but you’ve probably heard: There is a total solar eclipse today, August 21.

For the first time since 1979, the moon’s shadow will zip across the continental United States. The shadow will travel from Oregon to South Carolina in a swift 92 minutes. For those in the path of totality, total darkness will last only a couple of minutes. There and elsewhere in most of the United States, the moon will partially block the sun for around three hours.
If you don’t already have plans to travel to the 115-kilometer-or-so-wide path of totality, well, you’re probably too late. But here are some links to help you experience the eclipse, whether or not you’re able to see it in person.

The eclipse will be visible in all of North America — as well as in Central America and a small part of South America. Wondering what you’ll see where you live? Check out this interactive map from NASA or this cool tool from Vox.

Still need eclipse glasses? While many retailers have been sold out for days, some organizations are handing out free glasses at eclipse-watching events. Check your local TV/newspaper/radio stations’ newsfeeds for the latest. Make sure your glasses are safe.

No eclipse glasses? Never fear! You can still see the moon eclipsing the sun by making a pinhole projector or a box projector. Or just let sunlight shine through something that has holes, like a colander or Ritz Cracker (look at the ground to see the shape of the shadow the holes cast).

Watching with kids? Check out Growth Curve blogger Laura Sanders’ tips for protecting little ones’ eyes during the eclipse.
Which reminds me: Whatever you do, don’t look directly at the sun. Permanent damage to your eyes may result. If you’re in the path of totality, officials say it’s OK to look directly at the sun once the moon completely blocks it. But that’s very brief, so be prepared to quickly look away or shield your eyes once the moon slips out of total alignment.

Want to do more with your eclipse experience? It’s not too late to participate in a citizen science project.

Stuck indoors, or out of totality? Watch the livestream. NASA’s programming begins at noon Eastern on NASA TV, which you can watch at this link or right here:
Want some tunes to go along with it? The NASA interns made an eclipse playlist. There are also several Spotify playlists around, like this one from WXPN, this from the Washington Post and this one from the Boston Globe.

If all this excitement has you fancying a future in eclipse chasing, check out our interactive map of the next 15 total solar eclipses.

And let’s not forget that there will be a ton of science going on during the eclipse. Here are the big questions physicists and astronomers will seek to answer today.

Still want more? Follow us on Facebook and on Twitter for eclipse updates and RT’s of our correspondents in totality. Watch as the Science News team takes over the Society for Science & the Public’s Snapchat (Society4Science). And come back to Science News later today for a report from our astronomy writer, Lisa Grossman, who is spending the day in Casper, Wyo., with a research team that’s studying the sun’s wispy atmosphere, the corona.

Neandertal kids were a lot like kids today — at least in how they grew

A Neandertal child whose partial skeleton dates to around 49,000 years ago grew at the same pace as children do today, with a couple of exceptions. Growth of the child’s spine and brain lagged, a new study finds.

It’s unclear, though, whether developmental slowing in those parts of the body applied only to Neandertals or to Stone Age Homo sapiens as well. If so, environmental conditions at the time — which are currently hard to specify — may have reduced the pace of physical development similarly in both Homo species.
This ancient youngster died at 7.7 years of age, say paleoanthropologist Antonio Rosas of the National Museum of Natural Sciences in Madrid and colleagues. The scientists estimated the child’s age by counting microscopic enamel layers that accumulated daily as a molar tooth formed.

Previous excavations uncovered the child’s remains, as well as fossils of 12 other Neandertals, at a cave site in northwestern Spain called El Sidrόn.

Much — but not all —of the Neandertal child’s skeleton had matured to a point expected for present-day youngsters of the same age, the scientists report in the Sept. 22 Science. But bones at the top and in the middle of the spine had not fully fused, corresponding to a stage of development typical of 4- to 6- year-olds today. Also, the ancient child’s brain was still growing at an age when living humans’ brains have nearly or fully reached adult size. Signs of bone tissue being reshaped on the inner surface of the child’s braincase pointed to ongoing brain expansion. Rosas’ team calculated that the youngster’s brain volume was about 87.5 percent of that expected, on average, for Neandertal adults.

Neandertals’ slightly larger brains relative to people today may have required more energy, and thus more time, to grow, the researchers suggest. And they suspect that the growth of Neandertals’ bigger torsos, and perhaps spinal cords, slowed the extinct species’ backbone development in late childhood.

Rosas’ new study “reinforces what should have been apparent for some time — that Neandertal growth rates and patterns, except for those related to well-known differences in [skeletal shape], rarely differ from modern human variations,” says paleoanthropologist Erik Trinkaus of Washington University in St. Louis.

But researchers need to compare the El Sidrόn child to fossils of H. sapiens youngsters from the same time or later in the Stone Age, Trinkaus adds. Relative to kids today, ancient human youth may display slower growth rates comparable to those of the Neandertal child, he suspects.