When the earliest animals hauled themselves out of the ocean and evolved legs, they began flopping and eventually walking down the evolutionary path toward terrestrial life as we know it. The fossil remains of these first four-legged creatures, called tetrapods, have played a crucial role in understanding this sea-to-land transition. The spine is of particular interest, but it turns out that paleontologists had it backward.
Tetrapod fossils have long proven difficult to study since the bones often can’t be separated from the petrified material that surrounds them. Using a new modeling method, researchers bombarded these 360-million-year-old fossils with high-energy X-rays in order to make 3-D models of the ancient remains. The new method, reported in Nature this week, allowed researchers to isolate the otherwise-hidden bones and see them in their original orientation.
A stash of stones uncovered in a prehistoric dwelling in Panama could be the earliest evidence of traditional healing, or shamanic practice, in lower Central America.
Archaeologists used radiocarbon dating of charcoal samples located directly above and below the stones to estimate that the stones were left in the dwelling sometime between 4,000 and 4,800 years ago. Since the stones were clustered together, the researchers say the collection was probably deposited in a container that has since decomposed.
This Stone Age human jawbone contains a tooth with the
oldest filling ever found
We’re lucky to live in a modern age, an age when, instead of ripping out a painful cavity-ridden tooth, we can have dentists drill away the rotten bit and plug up the hole with a filling. But a new discovery reveals that fillings aren’t just modern conveniences: they date back to the Stone Age. Researchers have discovered that a tooth on a 6500-year-old human jawbone has a large cavity covered by a beeswax cap—making that wax the oldest dental filling ever discovered.
The Mayan rain god Chac
Droughts do far worse than brown our lawns—the water shortages and crop damage they mete out, and the fires fed by dry conditions, have effects that last long after rain returns. These events may even have civilization-destroying powers: although doubts remain, many researchers consider drought one of the leading contributors to the collapse of the Maya. And a new study published in Geophysical Research Letters finds that by cutting down forests, Mayans may have directly contributed to the droughts that brought about the downfall of their society.
Like modern civilizations, Mayans felled trees in order to harvest the raw material and clear land for cities and crops. Researchers modeled how this deforestation affected local climate conditions with computer simulations. Cleared land absorbs less solar energy, which means it releases less moisture to contribute to rainfall. By comparing untampered or regrown forest to reconstructions of the tree cover during Mayan occupation, researchers found that razed land could have reduced annual rainfall by 5 to 15 percent. This means that of the estimated drought during the height of Mayan civilization, 60 percent of the rainfall decrease was likely due to deforestation.
Back in the day, in the northern part of modern-day Laos, an early modern human died and its corpse washed into a nearby cave. Sure, it doesn’t sound like a particularly noteworthy event. But researchers dated the remains of this human’s skull to at least 46,000 years ago, making it the oldest modern human ever discovered in Southeast Asia.
Scientists discovered the skull fragments back in 2009, but have only this week published their findings in the Proceedings of the National Academy of Sciences. Features not found in any earlier specimens of the Homo genus, such as the absence of a brow ridge on the skull’s frontal bone, mark it as a modern human.
A cranium found in 1972 and the lower jaw of a newly discovered fossil,
shown reconstructed and combined above, are believed to be from
the same ancient hominid species.
The big-brained, upright primates of the genus Homo—the group to which we modern-day humans belong—evolved in East Africa around 2.4 million years ago. By half a million years later, Homo erectus, from whom we’re directly descended, was walking the plains near Lake Turkana in what is now Kenya. But anthropologists have increasingly come to believe that Homo erectus wasn’t the only hominid around. Three newly discovered fossils, detailed online this week in Nature, confirm that at least two other Homo species lived nearby—providing the strongest evidence yet that several evolutionary lineages split off in the genus’s early days.
Beakers found at Cahokia in the Midwest contain
traces of tea from the southeast
Some teas are not as soothing as others. “Black drink,” brewed from the holly Ilex vomitoria by Native Americans on what is now the southeastern coast of the United States, had the lovely side effect of inducing vomiting (though perhaps from ingredients other than the holly) and was a key part of a 16th-century religious purification ritual, according to European accounts. Researchers were recently surprised to learn, however, that it also seems to have traveled quite a bit: traces of black drink have now been found over 200 miles out of Ilex vomitoria’s coastal range at the site of Cahokia, an ancient city near modern-day St. Louis.
The Crusades were a time of religious conflict, when territory and castles were won with bloody battles and then quickly lost again—and with all that brouhaha, who had time to make new coins? When the Christian Knights Hospitaller buried a jug of 108 gold coins at the castle of Apollonia, a now-deserted stronghold north of modern-day Tel Aviv, they were probably hoping to preserve their hoard from the Egyptian soldiers then besieging the fortress. Although they never returned for their money, its recent discovery is telling researchers a lot about Crusader economics and raising new questions—like why the Christians used primarily gold dinars forged by the Fatimids hundreds of years earlier, rather than minting their own currency, something that would have demonstrated their wealth, power, and cultural identity. Many of the coins found in the crusader castle, oddly enough, are emblazoned with the names of Muslim sultans.
Image courtesy of the American Friends of Tel Aviv University
The healthy little brown bats roosting close to the bat
with white-nose syndrome risk infection with the fungus
The deadly fungus that causes white-nose syndrome is sweeping through North American bat populations, and little brown bats are adapting their behavior to avoid it. Although these bats typically clump together in large groups, they are now spreading out to roost separately, a change in behavior that may be helping the bat populations rebound. So what does a bat-killing fungus have to do with human prejudice? The bats’ trick of splitting up to survive contagion may also have led humans to divide into tribes and respond hostilely to members of different, potentially diseased groups.
In a post on Scientific American’s Guest Blog, biologist Rob Dunn writes about the link between infectious diseases and human prejudice.