From deep in the gold mines of South Africa’s Orange Free State has come evidence that there was some form of biologic activity on Earth at least 2.15 billion years ago. Polymerized hydrocarbon “chemo-fossils” found in the gold ores … [probably] were originally part of a rich bacterial and algal life in the Witwatersrand basin. Since the rock layers from which they come have been dated to about 2.15 billion years ago, it seems likely that photosynthesis existed on Earth before then. — Science News, March 18, 1967

UPDATE
Scientists still debate when early photo­synthesizing organisms called cyanobacteria began pumping oxygen into Earth’s atmosphere. Recent evidence suggests the microbes existed some 3.2 billion years ago (SN Online: 9/8/15), even though a larger oxygen surge didn’t happen until about 2.4 billion years ago (SN: 3/4/17 p. 9). Those tiny bacteria left an outsized impact on our planet, releasing extra oxygen into the atmosphere that paved the way for complex multicellular life like plants and animals.

Catch sight of someone scratching and out of nowhere comes an itch, too. Now, it turns out mice suffer the same strange phenomenon.

Tests with mice that watched itchy neighbors, or even just videos of scratching mice, provide the first clear evidence of contagious scratching spreading mouse-to-mouse, says neuroscientist Zhou-Feng Chen of Washington University School of Medicine in St. Louis. The quirk opens new possibilities for exploring the neuroscience behind the spread of contagious behaviors.
For the ghostly itch, experiments trace scratching to a peptide nicknamed GRP and areas of the mouse brain better known for keeping the beat of circadian rhythms, Chen and colleagues found. They report the results in the March 10 Science.

In discovering this, “there were lots of surprises,” Chen says. One was that mice, nocturnal animals that mostly sniff and whisker-brush their way through the dark, would be sensitive to the sight of another mouse scratching. Yet Chen had his own irresistible itch to test the “crazy idea,” he says.

Researchers housed mice that didn’t scratch any more than normal within sight of mice that flicked and thumped their paws frequently at itchy skin. Videos recorded instances of normal mice looking at an itch-prone mouse mid-scratch and, shortly after, scratching themselves. In comparison, mice with not-very-itchy neighbors looked at those neighbors at about the same frequency but rarely scratched immediately afterward.
Videos of scratching mice produced the same result. More audience itching and scratching followed a film of a mouse with itchy skin than one of a mouse poking about on other rodent business.
Next, researchers looked at how contagious itching plays out in the mouse nervous system. Brains of mice recently struck by contagious urges to scratch showed heightened activity in several spots, including, surprisingly, a pair of nerve cell clusters called the suprachiasmatic nuclei, or SCN. People have these clusters, too, deep in the brain roughly behind the eyes.

Other tests linked the contagious itching with GRP, previously identified as transmitting itch information elsewhere in the mouse nervous system. Mice didn’t succumb to contagious itching if they had no working genes for producing GRP or the molecule that detects it. Yet these mice still scratched when researchers irritated their skin. Also, in normal mice, a dose of GRP injected to the SCN brain regions brought on scratching without the sight of an itchy neighbor, but a dose of plain saline solution to same spots failed to set off much pawing.

It’s fine work, says dermatologist Gil Yosipovitch, who studies itching at the University of Miami. But he wonders how the mouse discovery might apply to people. So far, brain imagery in his own work has not turned up evidence for an SCN role in human contagious itching, he says.

SCN is better known as a circadian timekeeper, responding to cues in light. It’s unclear how the nerve cell clusters might orchestrate behavior based on seeing a scratching mouse, “a very specific and rich visual stimulus,” says psychologist and neuroscientist Henning Holle of the University of Hull in England. Other research suggests different brain regions are involved in contagious itching in people.

Tracking down the mechanisms behind the phenomenon is more than an intriguing science puzzle, Yosipovitch says. People troubled with strong, persistent itching are often unusually susceptible to contagious scratching, and new ideas for easing their misery would be welcome.

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.

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.”

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.

Even in the wilderness, humans are making a ruckus.

In 63 percent of America’s protected places — including parks, monuments and designated wilderness areas — sounds made by human activity are doubling the volume of background noise. And in 21 percent of protected places, this racket can make things 10 times noisier.

Enough clatter from cars, planes and suburban sprawl is seeping into wild places to diminish animals’ ability to hear mating calls and approaching predators, a team of researchers based in Colorado reports in the May 5 Science. Human noise doesn’t always have to be loud to override natural sounds, though. Some places are so quiet to begin with that even the smallest amount of human noise can dominate, the researchers found.

“The world is changing, and protected areas are getting louder — the last strongholds of diversity,” says Jesse Barber, an ecologist at Boise State University in Idaho. Studies like this one that show the impact of human-related noise across the entire country instead of in a single park are important, he says, because “this is the scale at which conservation occurs.”
Researchers measured the reach of human noise by tapping into a National Park Service dataset containing long-term audio recordings from 492 sites across the United States. At each site, the scientists linked the sound volume in decibels (averaged over weeks of recording and adjusted to prioritize the frequencies that human ears are most sensitive to) to the presence or absence of dozens of possible features. Such factors include whether the terrain was mountainous or flat, if there was a river nearby, and how close the site was to a highway or a farm.

Machine learning algorithms then predicted the volume in areas without audio monitors, based on the features of that place — and figured out how much of the noise in any given location came from human sources compared with natural ones.
The answer: quite a lot, even in the wilderness. In 12 percent of designated wilderness areas, for instance, human-made noises increase the median sound level 3 decibels above the predicted natural levels of noise. That means the area over which a bird’s squawk would register in human ears would be cut in half in those places.

The more stringent the protections on the land, the lower the noise pollution, says study coauthor Rachel Buxton, an ecologist at Colorado State University in Fort Collins. For example, some categories of land protection allow mining and timber harvesting in limited amounts, which can boost noise levels. Areas labeled as wilderness ban such activity almost entirely, though do permit livestock grazing. Overall, protected areas were 35 percent less noisy than nearby spots that weren’t protected in any way.

Land managed by the federal government also tended to be less impacted by human noise than land under local control. That might come as a surprise to anyone who’s faced a traffic jam trying to find a parking spot in Yosemite or Shenandoah national parks on a summer weekend. But unlike other U.S. land management agencies, the National Park Service “considers natural sounds to be a natural resource,” Buxton says.
Many national parks have instituted restrictions on airplanes flying overhead, for instance, and implemented public transit to decrease park traffic. So while the area around the visitor center might feel like an amusement park, chirping birds and gurgling streams can dominate the soundscape deeper in the park. This study suggests those noise control efforts might be making a difference.

Still, even a little extra noise can take a toll on the surrounding ecosystem. A humming highway can drown out birds’ mating calls or prevent predators from hearing rustling prey (SN: 2/21/15, p. 22). And species don’t need ears to be affected — the effects of excess noise “can really trickle through a community,” Buxton says. Plants often depend on birds to spread their seeds, or on bees to get pollinated. If noise changes those animals’ behavior, then the plants can face consequences, too.

“Noise is not strictly an urban phenomenon,” says Clint Francis, an ecologist at California Polytechnic State University in San Luis Obispo. There’s hope for wild areas, though. “Solutions to noise are often readily available,” he says. Quieter car engines and different types of road surfaces can all help reduce traffic noise, for example.

Quieter wild places can benefit humans, too. “When you’re in a park and you’re appreciating some sight, like the Grand Canyon, you also experience the sound of the river going by, the sound of the birds in the trees,” Buxton says. “It totally enhances your experience.”

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.

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 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.

A vaccine against meningitis has an unexpected side effect: It appears to target gonorrhea, too. If confirmed, the results represent the first instance of a vaccine reducing gonorrhea infections.

After receiving a vaccine aimed at a type of meningitis, people were less likely to contract gonorrhea, scientists report online June 10 in the Lancet. That’s a big deal because worldwide each year, an estimated 78 million people contract gonorrhea, a sexually transmitted disease that can cause pelvic inflammation, infertility and throat infections. Gonorrhea’s bacterial culprit, Neisseria gonorrhoeae, has developed resistance to many antibiotics, making treatment much more difficult. Some strains of gonorrhea can now resist all known antibiotics, the Word Health Organization announced July 7.
“We are in desperate need for new therapies,” says Christine Johnston, an infectious disease specialist at the University of Washington in Seattle. Attempts to make a gonorrhea vaccine have failed so far. The new results are “the first to show that vaccination against gonorrhea could be possible,” Johnston says.

Finding the link between the two diseases was partly “a story of serendipity,” says study coauthor Helen Petousis-Harris, a vaccinologist at the University of Auckland in New Zealand. She and others had noted curious declines in gonorrhea cases in New Zealand, Cuba and, to a lesser extent, Norway after people had been vaccinated against a group B meningococcal bacterium, a pathogen that can cause meningitis and blood infections.

Bacteria that cause meningitis and gonorrhea are actually close kin, sharing 80 to 90 percent of their DNA. “There was certainly biological plausibility, but we needed some proof” that the vaccine really did curb gonorrhea, Petousis-Harris says.

She and colleagues looked at data from the New Zealand national vaccine registry to see who received a meningococcal vaccine that was available from 2004 to 2008, called MeNZB. That vaccination information was combined with data on over 14,000 15- to 30-year-olds who had either gonorrhea, chlamydia or both in New Zealand between 2004 and 2016.

Compared with unvaccinated people, those who had received the vaccine were about a third less likely to contract gonorrhea, the researchers found. The researchers had no information about people’s exposure to gonorrhea, only whether people were treated for the infection at a clinic. No such link was found between the vaccine and chlamydia.
MeNZB is a type of vaccine called an outer membrane vesicle vaccine. By mimicking bacterial bits released as the bugs proliferate, the vaccine trains the immune system to recognize and attack the bacteria. That exact vaccine is no longer in use, but similar vaccines exist, including Bexsero, which was used to treat a meningitis B outbreak at Princeton University in 2013.

The researchers don’t yet know what part of the MeNZB vaccine may be protective against gonorrhea. “We need to understand what was magical about this vaccine,” Petousis-Harris says. That knowledge could help researchers design a more targeted gonorrhea vaccine. Other meningitis vaccines ought to be scrutinized, too, Petousis-Harris says. “It might be that we’ve got a vaccine out there that could make a significant difference.”

Novartis, the health care company that developed Bexsero, provided funds for the study, but had no input on the design or results, Petousis-Harris says. A different company, GlaxoSmithKline, has since bought Novartis’ vaccine division.

Any new treatment for gonorrhea will eventually spur the bacteria to develop resistance, says Teodora Wi, a medical officer at WHO’s Department of Reproductive Health and Research in Geneva. But a vaccine couldn’t be evaded so easily. The current result “provides a very important breakthrough in the development of gonorrhea vaccines,” she says.