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.”

[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.

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.

A mysterious group of microbes may be controlling the fate of carbon in the dark depths of the world’s oceans.

Nitrospinae bacteria, which use the nitrogen compound nitrite to “fix” inorganic carbon dioxide into sugars and other compounds for food and reproduction, are responsible for 15 to 45 percent of such carbon fixation in the western North Atlantic Ocean, researchers report in the Nov. 24 Science. If these microbes are present in similar abundances around the world — and some data suggest that the bacteria are — those rates may be global, the team adds.
The total amount of carbon that Nitrospinae fix is small when compared with carbon fixation on land by organisms such as plants or in the sunlit part of the ocean, says Maria Pachiadaki, a microbial ecologist at Bigelow Laboratory for Ocean Sciences in East Boothbay, Maine, who is lead author on the new study. “But it seems to be of major importance to the productivity and health of the 90 percent of the ocean that is too deep and too dark for photosynthesis.” These bacteria likely form the base of the food web in much of this enigmatic realm, she says.

Oceans cover more than two-thirds of Earth’s surface, and most of those waters are in the dark. In the shallow, sunlit part of the ocean, microscopic organisms called phytoplankton fix carbon dioxide through photosynthesis. But in the deep ocean where sunlight doesn’t penetrate, microbes that use chemical energy derived from compounds such as ammonium or hydrogen sulfide are the engines of that part of the carbon cycle.

Little has been known about which microbes are primarily responsible for this dark ocean carbon fixation. The likeliest candidates were a group of ammonium-oxidizing archaea (single-celled organisms similar to bacteria) known as Thaumarchaeota because they are the most abundant microbes in the dark ocean.

But there was no direct proof that these archaea are the main fixers in those waters, says Pachiadaki. In fact, previous studies of carbon fixation in these depths suggested that ammonium-oxidizers weren’t performing the task quickly enough to match observations, she says. “The energy gained from ammonium oxidation is not enough to explain the amount of the carbon fixed in the dark ocean.”
She and colleagues suspected that a different group of microbes might be bearing the brunt of the task. Nitrospinae bacteria that use the chemical compound nitrite were known to be abundant in at least some parts of the dark ocean, but the microbes weren’t well studied. So Pachiadaki’s team analyzed 3,463 genomes, or genetic blueprints, of single-celled organisms found in 39 seawater samples collected in the western North Atlantic Ocean, at depths ranging from “twilight” regions below about 200 meters to the ocean’s deepest zone below 9,000 meters. The team identified Nitrospinae as the most abundant bacteria, particularly in the twilight zone. Although still less abundant than the ammonium-oxidizing Thaumarchaeota, the nitrite-oxidizers are much more efficient at fixing carbon, requiring only a tiny amount of available nitrite.

And although scientists knew that these bacteria use nitrite to produce energy, the new study showed that the compound is the primary source of energy for the microbes. Marine microbiologist Frank Stewart of Georgia Tech in Atlanta says the study “exemplifies how advances in genomic methods can generate hypotheses about metabolism and ecology.” These findings suggest that scientists need to rethink how energy and materials cycle in the dark ocean, he says. “While this ocean realm remains underexplored, studies like this are models for how to close our knowledge gap.”

PHILADELPHIA — Protein-manufacturing factories within cells are picky about which widgets they construct, new research suggests. These ribosomes may not build all kinds of proteins, instead opting to craft only specialty products.

Some of that specialization may influence the course of embryo development, developmental biologist and geneticist Maria Barna of Stanford University School of Medicine and colleagues discovered. Barna reported the findings December 5 at the joint meeting of the American Society for Cell Biology and European Molecular Biology Organization.
Ribosomes, which are themselves made up of many proteins and RNAs, read genetic instructions copied from DNA into messenger RNAs. The ribosomes then translate those instructions into other proteins that build cells and carry out cellular functions. A typical mammalian cell may carry 10 million ribosomes. “The textbook view of ribosomes is that they are all the same,” Barna said. Even many cell biologists have paid little attention to the structures, viewing them as “backstage players in controlling the genetic code.”

But that view may soon change. Ribosomes actually come in many varieties, incorporating different proteins, Barna and colleagues found. Each variety of ribosome may be responsible for reading a subset of messenger RNAs, recent studies suggest. For instance, ribosomes containing the ribosomal protein RPS25 build all of the proteins involved in processing vitamin B12, Barna and colleagues reported July 6 in Molecular Cell. Vitamin B12 helps red blood cells and nerves work properly, among other functions. Perhaps other biological processes are also controlled, in part, by having specific types of ribosomes build particular proteins, Barna said.

In unpublished work presented at the meeting, Barna and colleagues also found that certain ribosome varieties may be important at different stages of embryonic development. The researchers coaxed embryonic stem cells growing in lab dishes to develop into many types of cells. The team then examined the ribosomal proteins found in each type of cell. Of the 80 ribosomal proteins examined, 31 changed protein levels in at least one cell type, Barna said. The finding may indicate that specialized ribosomes help set a cell’s identity.

Although Barna’s idea of diverse ribosomes goes against the classical textbook view, “the concept is not heretical at all,” says Vassie Ware, a molecular cell biologist at Lehigh University in Bethlehem, Pa., not involved in the work.
These findings may help explain why some people with mutations in certain ribosomal protein genes develop conditions such as Diamond-Blackfan anemia — a blood disorder in which the bone marrow doesn’t make enough red blood cells — but don’t have problems in other body tissues, Ware says.

That disease is caused by mutations in the RPL5 and RPL11 genes, which encode ribosomal building blocks. If all ribosomes were alike, people with mutations in ribosomal components should have malfunctions all over their bodies, or might not ever be born. RPL5 and RPL11 proteins may be part of specialized ribosomes that are important in the bone marrow but not elsewhere in the body.

Despite their name, pelican spiders aren’t massive, fish-eating monstrosities. In fact, the shy spiders in the family Archaeidae are as long as a grain of rice and are a threat only to other spiders.

Discovering a new species of these tiny Madagascar spiders is tough, but Hannah Wood has done just that — 18 times over.

Wood, an arachnologist at the Smithsonian National Museum of Natural History in Washington D.C., analyzed the genes and anatomy of live and museum pelican spider specimens to find these new species. She describes them in a paper published online January 11 in ZooKeys.
Like other pelican spiders, the new species have an elongated “neck” and beaklike pincers, or chelicerae. The way they use those long chelicerae to strike from a distance, earned them another name: assassin spiders. Once impaled, the helpless prey dangles from these meat hooks until the venom does its work (SN: 3/22/14, p. 4).

Probing the spiders’ tiny anatomy under a microscope, Wood looked for hints to distinguish one species from another. Arachnologists often look to spiders’ genitals: Males and females from the same species typically evolved specially shaped organs to mate. If the “lock” doesn’t fit the “key,” the spiders are likely of a different species.

Thanks to Wood, 18 more species of pelican spiders — some of which were previously misclassified — now have names. Eriauchenius rafohy honors an ancient Madagascar queen, and E. wunderlichi, an eminent arachanologist. Wood, one of the foremost experts on pelican spiders, says she expects there are still more species to find. Perhaps an E. woodi?

A teenage girl climbed into an underground cave around 13,000 years ago. Edging through the ink-dark chamber, she accidentally plunged to her death at the bottom of a deep pit.

Rising seas eventually inundated the cave, located on Central America’s Yucatán Peninsula. But that didn’t stop scuba divers from finding and retrieving much of the girl’s skeleton in 2007.

“First Face of America,” a new NOVA documentary airing February 7 on PBS, provides a closeup look at two dangerous underwater expeditions that resulted in the discovery and salvaging of bones from one of the earliest known New World residents, dubbed Naia.
The program describes how studies of Naia’s bones (SN: 6/14/14, p. 6) and of genes from an 11,500-year-old infant recently excavated in Alaska have generated fresh insights into how people populated the Americas. Viewers watch anthropologist and forensic consultant James Chatters, who directed scientific studies of Naia’s remains, as he reconstructs the ancient teen’s face and charts the lower-body injuries that testify to what must have been a rough life.
In one suspenseful scene, cameras record Chatters talking with scuba divers shortly before the divers descend into the submerged cave to collect Naia’s bones. The scientist describes how thousands of years of soaking in seawater have rendered the precious remains fragile. He uses a plaster cast of a human jaw to demonstrate for scuba diver Susan Bird how to handle Naia’s skull so that it stays intact while being placed in a padded box. Bird’s worried expression speaks volumes.

“On the day of the dive, there was so much tension, so many people on the verge of freaking out,” Bird recalls in the show. When the divers return from their successful mission, collective joy breaks out.
The scene then shifts to a lab where Chatters painstakingly re-creates what Naia looked like. Asian-looking facial features raise questions about how the ancient youth ended up in Central America. That’s where University of Alaska Fairbanks anthropologist Ben Potter enters the story. In 2013, Potter and colleagues excavated the remains of two infant girls at an Alaskan site dating nearly to Naia’s time. Analysis of DNA recovered from one of the infants , described in the Jan. 11 Nature , supports a scenario in which a single founding Native American population reached a land bridge that connected northeast Asia to North America around 35,000 years ago. As early as 20,000 years ago, those people had moved into their new continent, North America. Naia’s face reflects her ancestors’ Asian roots.
In tracing back how people ended up in the Americas, NOVA presents an outdated model of ancient humans moving out of Africa along a single path through the Middle East around 80,000 years ago. Evidence increasingly indicates that people started leaving Africa 100,000 years ago or more via multiple paths (SN: 12/24/16, p. 25). That’s a topic for another show, though. In this one, Naia reveals secrets about the peopling of the Americas with a lot of help from intrepid scuba divers and state-of-the-art analyses. It’s fitting that a slight smile creases her reconstructed face.