Best Citation Awards

Oldest rocks — Science News , July 21, 1973 Until recently, Greenland possessed the oldest known rocks in the world. They date back 3.7 billion years ( SN: 12/9/72, p. 374 ). Now granite and crystalline schist specimens … suggest that the Antarctic Continent is older. These specimens date back 4 billion years. Update: At about 4.3 billion years old, bedrock in northeastern Canada currently holds the title of oldest known rock on Earth ( SN: 4/15/17, p. 8 ). In Western Australia, scientists have found zircon crystals in bedrock that are even older, dating to about 4.4 billion years ago. For comparison, Earth is only about 4.5 billion years old. Since these ancient materials preserve information about early Earth, they have fueled ongoing debates about when and how Earth’s crust formed , when plate tectonics started and even when life on the planet first arose ( SN: 2/23/14; SN: 5/2/22; SN: 10/19/15 ). Additional clues that could help resolve the debates might lie on the moon

Blight Emily Monosson W.W. Norton & Co., $28.95 In the summer of 1904, American chestnut trees in the Bronx were in trouble. Leaves, normally slender and brilliantly green, were curling at the edges and turning yellow. Some tree limbs and trunks sported rust-colored splotches. By the next summer, almost every chestnut tree in the New York Zoological Park, now the Bronx Zoo, was dead or dying. By around 1940, almost every American chestnut across its native range, the eastern United States, was gone. The trees had been felled by a microscopic fiend: Cryphonectria parasitica , a fungus that causes chestnut blight. That fungus had been imported on Japanese chestnut trees. Once it arrived on U.S. soil, it spread like wildfire, driving the American chestnut ( Castanea dentata ) to functional extinction. Today, some still grow, though only as immature trees popping up from the still-living roots of long-gone trees. But these shoots have no hope of towering over the forest as ches

Rats are extremely playful creatures. They love playing chase, and they literally jump for joy when tickled. Central to this playfulness, a new study finds, are cells in a specific region of rats’ brains. Neurons in the periaqueductal gray, or PAG, are active in rats during different kinds of play , scientists report July 28 in Neuron . And blocking the activity of those neurons makes the rodents much less playful. The results give insight into a poorly understood behavior, particularly in terms of how play is controlled in the brain. “There are prejudices that it’s childish and not important, but play is an underrated behavior,” says Michael Brecht, a neuroscientist at Humboldt University in Berlin. Scientists think play helps animals develop resilience. Some even relate it to optimal functioning. “When you’re playing, you’re being your most creative, thoughtful, interactive self,” says Jeffrey Burgdorf, a neuroscientist at Northwestern University in Evanston, Ill., who was not inv

Earth has a cow problem. Cow agriculture is one of the largest emitters of climate-warming methane to the atmosphere. But adding a type of red algae known for its methane-inhibiting properties to cow feces might help. Doing so reduces the production of methane within feces by about 44 percent, researchers report July 13 in Frontiers in Sustainable Food Systems . That offers a promising new avenue to reduce overall methane emissions from cattle, the scientists say. Cow agriculture is responsible for nearly a quarter of the world’s emissions of methane , a potent greenhouse gas ( SN: 11/18/15; SN: 5/5/22 ). The cows make methane in their guts during digestion that is then released to the world, mostly via burps. A smaller — but not insignificant — amount of methane is also emitted directly from the cows’ feces during decomposition. Researchers have been actively seeking solutions to the gut-produced methane. Adding just a pinch — 0.5 percent of the dry feed — of the red algae Aspara

Honeybees and yellow jackets don’t look much like mathematicians — for one thing, they’re smaller. But collectively, the insects can solve a common architectural conundrum using a geometric solution that they evolved independently of each other. As their colonies grow, these bees and wasps eventually need to increase the size of the hexagonal cells that make up their nests. But nest material is expensive, and it’s hard to efficiently combine hexagons of different sizes into a single continuous array. Both the honeybees and wasps have solved this problem by mixing in some pairs of five-sided and seven-sided cells , which bridge the gap between different sizes of the six-sided hexagons, researchers report July 27 in PLOS Biology . This fix is close to the optimal solution to this problem, the team says. “We’ve known for a long time that the hexagonal comb bees and wasps use is the most efficient, stable shape,” says Lewis Bartlett, a honeybee biologist at the University of Georgia in A

A woman buried more than 2,400 years ago in what’s now northwestern China has galloped into a scientific afterlife atop the earliest directly dated horseback riding saddle. Researchers have radiocarbon dated the well-preserved, soft saddle to 727 B.C. to 396 B.C. Excavated at what’s known as the Yanghai cemetery, this expertly crafted piece of riding equipment is about as old as, or possibly older than, the previous record holders, archaeologist Patrick Wertmann of the University of Zurich and colleagues report in the September Archaeological Research in Asia . Soft saddles found in tombs of mobile herders and warriors from the Scythian Pazyryk culture of northern Asia date to 430 B.C. to 420 B.C. Those dates are inferred from analyses of tree rings in wood that was used to construct those chambers. Despite its simple design, “the Yanghai saddle was manufactured by a specialist familiar not only with needle- and leatherwork but with horse riding and the anatomy of horse and rider,”

Fat incinerator. Metabolism booster. Thermo activator. Some over-the-counter sports supplements advertise ingredients with purported performance-enhancing properties, but it’s anyone’s guess what’s really in that pill or powder. Just 11 percent of nearly 60 tested dietary supplements actually contain an accurate amount of key ingredients listed on the label, scientists report July 17 in JAMA Network Open . Forty percent did not contain a detectable amount of the ingredients at all. “I just had to shake my head,” says Pieter Cohen, a primary care doctor at Cambridge Health Alliance in Somerville, Mass. “It’s incredible that in 40 percent of the products, the manufacturer doesn’t even bother putting any [of the ingredient] in.” Cohen and his colleagues chemically analyzed 57 sports supplements with labels that listed R. vomitoria , methylliberine, halostachine, octopamine or turkesterone — plants or plant compounds that could potentially serve as stimulants or muscle-builders. Only 3

Forget Arizona or Florida — sun worshippers ought to head to the Atacama Desert in South America. It’s there that the sun’s rays on Earth are most intense , beating out places like Mount Everest and even, occasionally, rivaling the conditions on Venus, researchers report July 3 in the Bulletin of the American Meteorological Society . Satellite data have suggested that the Altiplano — a high-altitude plateau in the Atacama that straddles parts of Chile, Bolivia, Peru and Argentina — experiences the most intense levels of sunlight on Earth. But since satellites look down on our planet’s surface from afar, it’s important to verify that claim with on-the-ground data, says Raúl Cordero, a physicist at the University of Santiago in Chile. “How good are these estimates?” To answer that question, Cordero and colleagues set up a small atmospheric observatory, housed in two shipping containers, in the Chilean Altiplano. Since 2016, the researchers have been measuring solar radiation levels at

COIMBATORE, India — To better understand Equatorial Guinea’s tropical birds, ornithologists Luke Powell and Patricia Rodrigues scan the ground rather than the trees. They are searching for nests of driver ants ( Dorylus spp.). These voracious predators will march out of their underground nests and fan out into a meters-wide swarm, flushing out insects and worms from undergrowth. From the trees, birds swoop down to catch the fleeing insects. And where the ant swarms go, the birds follow. Swarms make humming and “tick tick tick” sounds, says Powell, of the University of Porto in Portugal. It is the sound of the ants — and of animals scurrying in panic ( SN: 8/12/02 ). “Then you hear the sounds of birds chirping at the edge [of the swarm], communicating.” Ant-following birds are well studied in the neotropical Americas. In Africa, however, “people have seen birds follow ants, but nobody has really looked” to see whether the animals have a specialized relationship, says Rodrigues from

The recent, record-breaking heat waves that have scorched the southwestern United States and northern Mexico, China and southern Europe were made dramatically more likely due to human-caused climate change, researchers report July 25 in a study from the World Weather Attribution network. “This is absolutely not a surprise,” climate scientist Friederike Otto of Imperial College London said at a July 24 news briefing. But “while the weather is changing as expected, how much it hurts us is larger than expected.” These intense and at times deadly heat waves are occurring as high-pressure systems stall across the Northern Hemisphere, creating barely budging heat domes ( SN: 7/19/23 ).  Phoenix, for example, has reached at least 43.3° C (110° Fahrenheit) every day for more than three weeks.  Otto and her colleagues used computers to simulate Earth’s climate, with and without human-caused climate change, to assess how likely the recent heat waves would have been under different climate c

The James Webb Space Telescope has spotted objects in the early universe that might be a new kind of star — one powered by dark matter. These “dark stars” are still hypothetical. Their identification in JWST images is far from certain. But if any of the three candidates — reported in the July 25 Proceedings of the National Academy of Sciences — turn out to be this new type of star, they could offer a glimpse of star formation in the early universe, hint at the nature of dark matter and possibly explain the origins of supermassive black holes. First proposed in 2007 by cosmologist Katherine Freese and colleagues, dark stars might have been some of the first types of stars to form in the universe ( SN: 1/1/08 ). Though dark stars have yet to be observed, they’re thought to be powered by heat from dark matter interactions rather than by nuclear fusion reactions like in the sun. Dark stars “would be very weird looking,” says Freese, of the University of Texas at Austin. The hypotheti

Some newly reported clumps of cells growing in lab dishes have been hailed as the closest things to human embryos that scientists have ever made in the lab. These entities are human embryo models — masses of cells created from stem cells that mimic some properties of certain stages of embryo development. The achievement gives researchers a chance to look at human development beyond the first week or so, when an embryo must implant in the uterus to develop further. That post-implantation stage hadn’t been re-created in lab dishes — until now.  Six studies reported in June and July describe the embryo models, which have generated excitement and concern in equal measure. For researchers working on these embryo models, the faux embryos are new tools to gain insight into the “black box” of human development, after embryos implant in the uterus. They are useful because donated human embryos are in short supply, and there are limits on the types of experiments researchers can perform on th

Calamity after calamity befell Europe at the beginning of the so-called Dark Ages. The Roman Empire collapsed in the late fifth century. Volcanic eruptions in the mid-sixth century blocked out the sun, causing crop failure and famine across the Northern Hemisphere. Meanwhile, the Justinian Plague arrived, killing, by some estimates, nearly half of everybody in Constantinople, the capital of the Byzantine Empire, and scores of others elsewhere. And then, on June 8, 793, a group of marauders attacked a small island off the northeastern coast of Great Britain. As Christian monks noted in the Anglo-Saxon Chronicle , “heathen men destroyed God’s church in Lindisfarne island by fierce robbery and slaughter.” With that description, the Vikings entered the annals of medieval history as merciless raiders, having also killed a local official in southern Great Britain in 789. From today’s perspective, these Norse seafarers burst into existence seemingly out of nowhere. Exactly when and why the