After a giant asteroid hit Earth about 66 million years ago, the planet’s climate went on a roller coaster ride.
The space rock’s impact set off tsunamis and wildfires before climate-chilling clouds of sulfur gas engulfed the planet for decades, wiping out most life (SN: 11/25/17, p. 14). As these clouds dissipated, billions of tons of carbon dioxide, which spewed into the atmosphere when the asteroid hit, fueled roughly 100,000 years of global warming, new data suggest. Analyzing fossilized fish bits hints that the influx of the greenhouse gas raised the temperature of the ocean on average by 5 degrees Celsius, scientists report online May 24 in Science. It’s not surprising that the climate heated up after the collision, which left a 200-kilometer-wide crater centered around what’s now Chicxulub, Mexico, says Johan Vellekoop, a geologist at KU Leuven in Belgium. But finding evidence to back up the warming claim has been challenging.
A common way to estimate past temperatures on Earth is to measure the proportion of heavier to lighter forms of oxygen in the carbonate shells left behind by dead invertebrates. Animals incorporate different oxygen forms into shells, teeth and bones at different rates depending on temperature. But carbonate fossils from around the time of the impact aren’t well enough preserved to be a reliable thermometer.
Instead, paleogeologist Ken MacLeod of the University of Missouri in Columbia and colleagues analyzed those same types of oxygen ratios in a crushed jumble of fish bones, teeth and scales — a different way to measure past temperatures. The team collected sediment samples from a section of rock in what’s now El Kef, Tunisia, that records the transition between the periods before and after the impact in its layers. (Samples from 2 meters of rock laid down before the impact and 6.6 meters laid down after the strike recorded almost 250,000 years of geologic history.) Back in the lab, the researchers spent hours peering through microscopes to sort out glassy, amber fish teeth and mineralized scales and measure the oxygen content within them. The ratio of heavier oxygen to lighter decreased by about 1 percent in the fish bits collected after the impact compared with those pieces from before the impact, the team found. That change translates to an increase in seawater temperature of about 5 degrees Celsius — a substantial amount. The elevated temperatures persisted for about 100,000 years before the planet cooled down again, an analysis of fish debris collected from different levels of rock showed. While the study looked only at ocean temperature, air temperature would probably reflect that increase, too, MacLeod says.
“It’s a pretty robust result,” says Clay Tabor, a climate scientist at the University of Connecticut in Hartford. But getting similar results from sites elsewhere in the world would boost the case that this was a global effect and not a local fluke, he says.
The story is far from over, MacLeod agrees. It’s not clear how long after the impact the warming began, for instance. His team hopes to analyze fish debris from other sites that might reveal finer-scale changes in temperature.
Nothing against trees. But maybe it’s better not to get too dependent on them if you want to survive a big flaming space object crashing into Earth.
The asteroid impact that caused a mass extinction 66 million years probably also triggered the collapse of forests worldwide, a new investigation of the plant fossil record concludes. Needing trees and extensive plant cover for nesting or food could have been a fatal drawback for winged dinosaurs, including some ancient birds. Reconstructing the ecology of ancient birds suggests that modern fowl descended from species that survived because they could live on the ground, an international research team proposes in the June 4 Current Biology. “You probably would have died anyway regardless of habitat,” says study coauthor Daniel Field, an evolutionary paleobiologist at the University of Bath in England. “But if you could get along on the ground, you at least had a shot at surviving across this devastated landscape.”
The shock wave from the strike probably flattened trees within a radius of 1,500 kilometers, Field says. Wildfires ignited around the planet and then came the acid rain. Clouds of ash and dust may have darkened the sky for several years, and researchers suspect that photosynthesis waned. Yet some lucky birds, but no other dinosaurs, survived the hellscape.
For clues to what made a survivor, researchers turned to fossilized pollen from before and after the fiery impact. Abundant kinds of flower-bearing and cone-bearing plants left pollen just before the asteroid hit and again starting about a thousand years afterward. In between those times of diversity, however, ferns dominated, the team notes. A kind of “disaster flora,” ferns (making spores instead of flowers and seeds) do well at recolonizing land. Seed plants, however, weren’t thriving.
Analyzing evolutionary histories of modern birds supports the idea of tree dependence as a vulnerability for the earliest fowl, the researchers say. Specialists in bird evolution now generally agree on the lowest, oldest branches of the bird family tree, Field says. The bottommost one, for instance, includes such modern species as ground-dwelling ostriches and smaller, flight-capable birds called tinamous, which might be more like the ancient birds that dodged extinction. Working backward along these low branches, researchers used fossils and known bird traits to reconstruct the most likely lifestyles of the earliest survivors. These probably weren’t tree-dependent birds, the researchers conclude.
The glory days of dinosaurs had had plenty of flying tree-dwellers. So far, paleontologists have identified at least 80 kinds of what are called “opposite birds,” the Enantiornithes (SN: 2/4/17, p. 26). “If you saw one flying around today, you’d say, ‘Well, that’s a bird,’ ” Field explains. Their feet looked like those of birds that perch on tree limbs, so he’s not surprised that a fossil of an opposite bird from this probably arboreal group has never been found in rock formed after the dino doomsday.
What did happen, however, was that when trees and forests came back after the disaster, birds quickly evolved arboreal lifestyles, the team says.
Many people don’t realize that birds almost died off during the mass extinction, too, says paleontologist Stephen Brusatte of the University of Edinburgh who has studied bird evolution but was not involved in the new study. What let the few survivors squeak through, he says, has been a mystery for a long time. The whole scenario of a ground-dweller’s advantage and then a return to the trees “makes a lot of intuitive sense.”
The veteran Opportunity rover isn’t dead yet. Currently, the craft is in a deep sleep to ride out a massive Martian dust storm, NASA officials said in a briefing on June 13. The rover may wake itself up when the storm ends.
Opportunity is enveloped in a vast dust storm that grew from a small patch spotted on May 30 to cover a quarter of the planet by June 12 (SN Online: 6/11/18). Too little sunlight is reaching the rover’s solar panels, so Opportunity is in low-power mode — just barely enough to run the rover’s internal clock — until its batteries can charge again. The team hasn’t heard from Opportunity since June 10, and no transmissions are expected until the storm clears. The Martian summer is just beginning, so the rover should stay warm enough to survive for a long time in this mode, said Opportunity’s project manager John Callas, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“When the skies clear and the rover begins to power up, it should be able to communicate with us,” he said. That’s not to say the team isn’t worried. Based on past storms, the wait could be anywhere from a few weeks to a few months. “It’s like you have a loved one in a coma in the hospital,” Callas said. “You have the doctors telling you that, ‘OK, you just have to give it time and she’ll wake up,’… but if it’s your 97-year-old grandmother, you’re going to be very concerned. And so we are. By no means are we out of the woods here.”
Opportunity landed on Mars on January 25, 2004, and was supposed to last 90 Martian days. It has now spent 5,113 Martian days driving more than 45 kilometers.
About 99 million years ago, tiny frogs hopped through a wet, tropical forest — and an unlucky few ran afoul of some tree sap. Four newly described frog fossils, preserved in amber, offer the earliest direct evidence of ancient frogs living in a humid tropical clime — just as many modern amphibians do.
None of the frog fossils is complete, making it difficult to place the frogs within their family tree: One has a partial skull and another a froggy outline, although CT scanning revealed no remaining skeletal material inside the impression. So researchers dubbed all four fossils Electrorana limoae (electrum for “amber” and rana for “frog”) in a study published June 14 in Scientific Reports. Anatomy-wise, the ancient frogs most resemble a modern group that includes fire-bellied toads.
The fossil record contains relatively few frogs, despite the amphibians’ more than 200-million-year history. The frog fossils that do exist suggest that frogs have looked distinctly — well, froggy — for hundreds of millions of years, says study coauthor David Blackburn, an amphibian biologist at the Florida Museum of Natural History in Gainesville. “The aspects that make them diverse are not their skeletons, it’s their ecologies, natural histories, reproductive modes. Things that are really hard to find in the fossil record.”
That’s what makes the amber specimens so interesting: The chunks also contain preserved spiders, velvet worms and bamboo — all pointing to a tropical environment. Such paleoecological evidence offers scientists a rare glimpse into the life and times of tropical frogs of old.
Making day-to-day activities more vigorous for a few minutes — such as briefly stepping up the pace of a walk — could offer people who don’t exercise some of the health benefits that exercisers enjoy.
That’s according to a new study of roughly 25,000 adults who reported no exercise in their free time. Those who incorporated three one- to two-minute bursts of intense activity per day saw a nearly a 40 percent drop in the risk of death from any cause compared with those whose days didn’t include such activity. The risk of death from cancer also fell by nearly 40 percent, and the risk of death from cardiovascular disease dropped almost 50 percent, researchers report online December 8 in Nature Medicine.
In a comparison with around 62,000 people who exercised regularly, including runners, gym-goers and recreational cyclists, the mortality risk reduction was similar.
“This study adds to other literature showing that even short amounts of activity are beneficial,” says Lisa Cadmus-Bertram, a physical activity epidemiologist at the University of Wisconsin–Madison, who was not involved in the research. “So many people are daunted by feeling that they don’t have the time, money, motivation, transportation, etc. to go to a gym regularly or work out for long periods of time,” she says. “The message we can take is that it is absolutely worth doing what you can.”
Emmanuel Stamatakis, an epidemiologist at the University of Sydney, and his colleagues analyzed a subset of records from the UK Biobank, a biomedical database containing health information on half a million people in the United Kingdom. The study’s non-exercising participants — more than half of whom were women and were 62 years old on average — had worn movement-tracking devices for a week.
Over an average seven years of follow-up, for those whose days included three to four bursts of activity, the mortality rate was 4.2 deaths from any cause per 1,000 people for one year. For those with no activity bursts, it was 10.4 deaths per 1,000 people for one year.
The researchers were looking for bursts of vigorous activity that met a definition determined in a laboratory study, including reaching at least 77 percent of maximum heart rate and at least 64 percent of maximum oxygen consumption. In real life, the signs that someone has reached the needed intensity level are “an increase in heart rate and feeling out of breath” in the first 15 to 30 seconds of an activity, Stamatakis says.
Regular daily activities offer several opportunities for these vigorous bursts, he says. “The simplest one is maximizing walking pace for a minute or two during any regular walk.” Other options, he says, include carrying grocery bags to the car or taking the stairs. “The largest population health gains will be realized by finding ways to get the least physically active people to move a little more.”
Look closely at a snowflake, and you’ll observe a one-of-a-kind gossamer lattice, its growth influenced by ambient conditions like temperature and humidity. Turns out, this sort of intricate self-assemblage can also occur in metals, researchers report in the Dec. 9 Science.
In pools of molten gallium, physicist Nicola Gaston and colleagues grew zinc nanostructures with symmetrical, hexagonal crystal frameworks. Such metal snowflakes could be useful for catalyzing chemical reactions and constructing electronics, says Gaston, of the MacDiarmid Institute for Advanced Materials and Nanotechnology at the University of Auckland in New Zealand.
“Self-assembly is the way nature makes nanostructures,” she says. “We’re trying to learn to do the same things.” Figuring out how to craft tiny, complex metal shapes in fewer steps and with less energy could be a boon for manufacturers.
The researchers chose gallium as a growth medium, due to its relatively low melting point, ability to dissolve many other metals and the tendency for its atoms to loosely organize while in a liquid state.
After mixing zinc into the gallium, the team subjected the alloy to elevated temperatures and different pressures, and then let the mixture cool to room temperature. The loose ordering of gallium atoms appeared to coax the crystallizing zinc to bloom into symmetrical, hexagonal structures resembling natural snowflakes and other shapes, the team found. It’s somewhat like how a fruit tray imparts order on the fruits stacked within, Gaston says.
The future may be bright for research into applications of gallium and other low-temperature liquid metals. “Not to take that snowflake metaphor too far, but [this work] really hints at new branches for scientific discovery,” Gaston says.
Meet the metric system’s newest prefixes: ronna-, quetta-, ronto- and quecto-.
Adopted November 18 at the 27th General Conference on Weights and Measures in Versailles, France, ronna- and quetta- describe exceedingly large numbers while ronto- and quecto- describe the exceedingly small. This is the first time that the International System of Units, or SI, has expanded since 1991, when the prefixes zetta-, yotta-, zepto and yocto- were added (SN: 1/16/93).
Numerically, ronna- is 1027 (that’s a digit followed by 27 zeroes) and quetta- is 1030 (30 zeroes). Their tiny counterparts ronto- and quecto- also refer to 27 and 30 zeroes, but those come after a decimal point. Until now, yotta- and yocto- (24 zeros) capped off the metric system’s range.
Science News spoke with Richard Brown, head of metrology at the National Physical Laboratory in Teddington, England, about what the latest SI expansion means for science. The following conversation has been edited for clarity and brevity.
SN: Why do we need the new prefixes?
Brown: The quantity of data in the world is increasing exponentially. And we expect that to continue to increase and probably accelerate because of quantum computing, digitalization and things like that. At the same time, this quantity of data is starting to get close to the top range of the prefixes we currently use. People start to ask what comes next?
SN: Where do the prefix names come from?
Brown: About five years ago, I heard a BBC podcast about these new names for quantities of data. And the two that they mentioned were brontobyte and hellabyte. Brontobyte, I think comes from brontosaurus being a big dinosaur and hellabyte comes from “‘hell of a big number.”
The problem with those from a metrology point of view, or measurement point of view, is they start with letters B and H, which already are in use for other units and prefixes. So we can’t have those as names. [It was clear] that we had to do something official because people were starting to need these prefixes. R and Q are not used for anything else, really, in terms of units or SI prefixes. [The prefix names themselves are] very, very loosely based on the Greek and Latin names for nine and 10. SN: How will the prefixes be used?
Brown: The whole point of the International System of Units is it’s an accepted global system, which if you use, you will be understood.
When you use a prefix with a unit, it means that the number associated with the unit changes. And people like small numbers that they can understand. So you can express the mass of the Earth in terms of ronnagrams; it’s six ronnagrams. And equally the mass of Jupiter is two quettagrams. Some good examples of [small numbers] are that the mass of an electron is about one rontogram, and the mass of one bit of data as stored on a mobile phone is around one quectogram.
I think the use of a suitable prefix makes things more understandable. And I think we shouldn’t forget that even if there’s not always a direct scientific usage immediately, they will gain traction over time.
Tyrannosaurus rex isn’t just a king to paleontologists — the dinosaur increasingly reigns over the world of art auctions. A nearly complete skeleton known as Stan the T. rex smashed records in October 2020 when a bidding war drove its price to $31.8 million, the highest ever paid for any fossil. Before that, Sue the T. rex held the top spot; it went for $8.3 million in 1997.
That kind of publicity — and cachet — means that T. rex’s value is sky-high, and the dinosaur continues to have its teeth firmly sunk into the auction world in 2022. In December, Maximus, a T. rex skull, will be the centerpiece of a Sotheby’s auction in New York City. It’s expected to sell for about $15 million.
Another T. rex fossil named Shen was anticipated to sell for between $15 million and $25 million at a Christie’s auction in Hong Kong in late November. However, the auction house pulled it over concerns about the number of replica bones used in the fossil. “These are astronomical sums of money, really surprising sums of money,” says Donna Yates, a criminologist at Maastricht University in the Netherlands who studies high-value collectibles.
Stan’s final price “was completely unexpected,” Yates says. The fossil was originally appraised at about $6 million — still a very large sum, though nothing like the final tally, which was the result of a three-way bidding war.
But the staggering amounts of money T. rex fossils now fetch at auction can mean a big loss for science. At those prices, the public institutions that might try to claim these glimpses into the deep past are unable to compete with deep-pocketed private buyers, researchers say.
One reason for the sky-high prices may be that T. rex fossils are increasingly being treated more like rare works of art than bits of scientific evidence, Yates says. The bones might once have been bought and sold at dusty “cowboy fossil” dealerships. But nowadays these fossils are on display in shiny gallery spaces and are being appraised and marketed as rare objets d’art. That’s appealing to collectors, she adds: “If you’re a high-value buyer, you’re a person who wants the finest things.”
But fossils’ true value is the information they hold, says Thomas Carr, a paleontologist at Carthage College in Kenosha, Wis. “They are our only means of understanding the biology and evolution of extinct animals.”
Keeping fossils of T. rex and other dinosaurs and animals in public repositories, such as museums, ensures that scientists have consistent access to study the objects, including being able to replicate or reevaluate previous findings. But a fossil sold into private or commercial hands is subject to the whim of its owner — which means anything could happen to it at any time, Carr says. “It doesn’t matter if [a T. rex fossil] is bought by some oligarch in Russia who says scientists can come and study it,” he says. “You might as well take a sledgehammer to it and destroy it.”
A desire for one’s own T. rex There are only about 120 known specimens of T. rex in the world. At least half of them are owned privately and aren’t available to the public. That loss is “wreaking havoc on our dataset. If we don’t have a good sample size, we can’t claim to know anything about [T. rex],” Carr says.
For example, to be able to tell all the ways that T. rex males differed from females, researchers need between 70 and 100 good specimens for statistically significant analyses, an amount scientists don’t currently have.
Similarly, scientists know little about how T. rex grew, and studying fossils of youngsters could help (SN: 1/6/20). But only a handful of juvenile T. rex specimens are publicly available to researchers. That number would double if private specimens were included.
Museums and academic institutions typically don’t have the kind of money it takes to compete with private bidders in auctions or any such competitive sales. That’s why, in the month before Stan went up for auction in 2020, the Society for Vertebrate Paleontology, or SVP, wrote a letter to Christie’s asking the auction house to consider restricting bidding to public institutions. The hope was that this would give scientists a fighting chance to obtain the specimens.
But the request was ignored — and unfortunately may have only increased publicity for the sale, says Stuart Sumida, a paleontologist at California State University in San Bernardino and SVP’s current vice president. That’s why SVP didn’t issue a public statement this time ahead of the auctions for Shen and Maximus, Sumida says, though the organization continues to strongly condemn fossil sales — whether of large, dramatic specimens or less well-known creatures. “All fossils are data. Our position is that selling fossils is not scientific and it damages science.”
Sumida is particularly appalled at statements made by auction houses that suggest the skeletons “have already been studied,” an attempt to reassure researchers that the data contained in that fossil won’t be lost, regardless of who purchases it. That’s deeply misleading, he says, because of the need for reproducibility, as well as the always-improving development of new analysis techniques. “When they make public statements like that, they are undermining not only paleontology, but the scientific process as well.”
And the high prices earned by Stan and Sue are helping to drive the market skyward, not only for other T. rex fossils but also for less famous species. “It creates this ripple effect that is incredibly damaging to science in general,” Sumida says. Sotheby’s, for example, auctioned off a Gorgosaurus, a T. rex relative, in July for $6.1 million. In May, a Deinonychus antirrhopus — the inspiration for Jurassic Park’s velociraptor — was sold by Christie’s for $12.4 million.
Protecting T. rex from collectors Compounding the problem is the fact that the United States has no protections in place for fossils unearthed from the backyards or dusty fields of private landowners. The U.S. is home to just about every T. rex skeleton ever found. Stan, Sue and Maximus hail from the Black Hills of South Dakota. Shen was found in Montana.
As of 2009, U.S. law prohibits collecting scientifically valuable fossils, particularly fossils of vertebrate species like T. rex, from public lands without permits. But fossils found on private lands are still considered the landowner’s personal property. And landowners can grant digging access to whomever they wish. Before the discovery of Sue the T. rex (SN: 9/6/14), private owners often gave scientific institutions free access to hunt for fossils on their land, says Bridget Roddy, currently a researcher at the legal news company Bloomberg Law in Washington, D.C. But in the wake of Sue’s sale in 1997, researchers began to have to compete for digging access with commercial fossil hunters.
These hunters can afford to pay landowners large sums for the right to dig, or even a share of the profits from fossil sales. And many of these commercial dealers sell their finds at auction houses, where the fossils can earn far more than most museums are able to pay.
Lack of federal protections for paleontological resources found on private land — combined with the large available supply of fossils — is a situation unique to the United States, Roddy says. Fossil-rich countries such as China, Canada, Italy and France consider any such finds to be under government protection, part of a national legacy.
In the United States, seizing such materials from private landowners — under an eminent domain argument — would require the government to pay “just compensation” to the landowners. But using eminent domain to generally protect such fossils wouldn’t be financially sustainable for the government, Roddy says, not least because most fossils dug up aren’t of great scientific value anyway.
There may be other, more grassroots ways to at least better regulate fossil sales, she says. While still a law student at DePaul University in Chicago, Roddy outlined some of those ideas in an article published in Texas A&M Journal of Property Law in May.
One option, she suggests, is for states to create a selective sales tax attached to fossil purchases, specifically for buyers who intend to keep their purchases in private collections that are not readily available to the public. It’s “similar to if you want to buy a pack of cigarettes, which is meant to offset the harm that buying cigarettes does to society in general,” Roddy says. That strategy could be particularly effective in states with large auction houses, like New York.
Another possibility is to model any new, expanded fossil preservation laws on existing U.S. antiquities laws, intended to preserve cultural heritage. After all, Roddy says, fossils aren’t just bones, but they’re also part of the human story. “Fossils have influenced our folklore; they’re a unifier of humanity and culture rather than a separate thing.”
Though fossils from private lands aren’t protected, many states do impose restrictions on searches for archaeological and cultural artifacts, by requiring those looking for antiquities to restore excavated land or by fining the excavation of certain antiquities without state permission. Expanding those restrictions to fossil hunting, perhaps by requiring state approval through permits, could also give states the opportunity to purchase any significant finds before they’re lost to private buyers.
Preserving fossils for science and the public Such protections could be a huge boon to paleontologists, who may not even know what’s being lost. “The problem is, we’ll never know” all the fossils that are being sold, Sumida says. “They’re shutting scientists out of the conversation.”
And when it comes to dinosaurs, “so many of the species we know about are represented by a single fossil,” says Stephen Brusatte, a paleontologist at the University of Edinburgh. “If that fossil was never found, or disappeared into the vault of a collector, then we wouldn’t know about that dinosaur.”
Or, he says, sometimes a particularly complete or beautifully preserved dinosaur skeleton is found, and without it, “we wouldn’t be able to study what that dinosaur looked like, how it moved, what it ate, how it sensed its world, how it grew.”
The point isn’t to put restrictions on collecting fossils so much as making sure they remain in public view, Brusatte adds. “There’s nothing as magical as finding your own fossils, being the first person ever to see something that lived millions of years ago.” But, he says, unique and scientifically invaluable fossils such as dinosaur skeletons should be placed in museums “where they can be conserved and studied and inspire the public, rather than in the basements or yachts of the oligarch class.”
After its record-breaking sale, Stan vanished for a year and a half, its new owners a mystery. Then in March 2022, news surfaced that the fossil had been bought by the United Arab Emirates, which stated it intends to place Stan in a new natural history museum.
Sue, too, is on public view. The fossil is housed at Chicago’s Field Museum of Natural History, thanks to the pooled financial resources of the Walt Disney Corporation, the McDonald Corporation, the California State University System and others. That’s the kind of money it took to get the highest bid on a T. rex 25 years ago.
And those prices only seem to be going up. Researchers got lucky with Sue, and possibly Stan.
As for Shen, the fossil’s fate remains in limbo: It was pulled from auction not due to outcry from paleontologists, but over concerns about intellectual property rights. The fossil, at 54 percent complete, may have been supplemented with a polyurethane cast of bones from Stan, according to representatives of the Black Hills Institute of Geological Research in Hill City, S.D. That organization, which discovered Stan, retains a copyright over the skeleton.
In response to those concerns, Christie’s pulled the lot, and now says that it intends to loan the fossil to a museum. But this move doesn’t reassure paleontologists. “A lot of people are pleased that the sale didn’t go through,” Sumida says. “But it sort of just kicks the can down the road.… It doesn’t mean they’re not going to try and sell it in another form, somewhere down the road.”
Ultimately, scientists simply can’t count on every important fossil finding its way to the public, Carr says. “Those fossils belong in a museum; it’s right out of Indiana Jones,” he says. “It’s not like they’re made in a factory somewhere. Fossils are nonrenewable resources. Once Shen is gone, it’s gone.”
The infant universe transforms from a featureless landscape to an intricate web in a new supercomputer simulation of the cosmos’s formative years.
An animation from the simulation shows our universe changing from a smooth, cold gas cloud to the lumpy scattering of galaxies and stars that we see today. It’s the most complete, detailed and accurate reproduction of the universe’s evolution yet produced, researchers report in the November Monthly Notices of the Royal Astronomical Society.
This virtual glimpse into the cosmos’s past is the result of CoDaIII, the third iteration of the Cosmic Dawn Project, which traces the history of the universe, beginning with the “cosmic dark ages” about 10 million years after the Big Bang. At that point, hot gas produced at the very beginning of time, about 13.8 billion years ago, had cooled to a featureless cloud devoid of light, says astronomer Paul Shapiro of the University of Texas at Austin. Roughly 100 million years later, tiny ripples in the gas left over from the Big Bang caused the gases to clump together (SN: 2/19/15). This led to long, threadlike strands that formed a web of matter where galaxies and stars were born.
As radiation from the early galaxies illuminated the universe, it ripped electrons from atoms in the once-cold gas clouds during a period called the epoch of reionization, which continued until about 700 million years after the Big Bang (SN: 2/6/17).
CoDaIII is the first simulation to fully account for the complicated interaction between radiation and the flow of matter in the universe, Shapiro says. It spans the time from the cosmic dark ages and through the next several billion years as the distribution of matter in the modern universe formed.
The animation from the simulation, Shapiro says, graphically shows how the structure of the early universe is “imprinted on the galaxies today, which remember their youth, or their birth or their ancestors from the epoch of reionization.”
An ancient hominid dubbed Homo naledi may have lit controlled fires in the pitch-dark chambers of an underground cave system, new discoveries hint.
Researchers have found remnants of small fireplaces and sooty wall and ceiling smudges in passages and chambers throughout South Africa’s Rising Star cave complex, paleoanthropologist Lee Berger announced in a December 1 lecture hosted by the Carnegie Institution of Science in Washington, D.C.
“Signs of fire use are everywhere in this cave system,” said Berger, of the University of the Witwatersrand, Johannesburg.
H. naledi presumably lit the blazes in the caves since remains of no other hominids have turned up there, the team says. But the researchers have yet to date the age of the fire remains. And researchers outside Berger’s group have yet to evaluate the new finds.
H. naledi fossils date to between 335,000 and 236,000 years ago (SN: 5/9/17), around the time Homo sapiens originated (SN: 6/7/17). Many researchers suspect that regular use of fire by hominids for light, warmth and cooking began roughly 400,000 years ago (SN: 4/2/12).
Such behavior has not been attributed to H. naledi before, largely because of its small brain. But it’s now clear that a brain roughly one-third the size of human brains today still enabled H. naledi to achieve control of fire, Berger contends.
Last August, Berger climbed down a narrow shaft and examined two underground chambers where H. naledi fossils had been found. He noticed stalactites and thin rock sheets that had partly grown over older ceiling surfaces. Those surfaces displayed blackened, burned areas and were also dotted by what appeared to be soot particles, Berger said.
Meanwhile, expedition codirector and Wits paleoanthropologist Keneiloe Molopyane led excavations of a nearby cave chamber. There, the researchers uncovered two small fireplaces containing charred bits of wood, and burned bones of antelopes and other animals. Remains of a fireplace and nearby burned animal bones were then discovered in a more remote cave chamber where H. naledi fossils have been found.
Still, the main challenge for investigators will be to date the burned wood and bones and other fire remains from the Rising Star chambers and demonstrate that the fireplaces there come from the same sediment layers as H. naledi fossils, says paleoanthropologist W. Andrew Barr of George Washington University in Washington, D.C., who wasn’t involved in the work.
“That’s an absolutely critical first step before it will be possible to speculate about who may have made fires for what reason,” Barr says.
