Saturday, May 8, 2021

Our Stone Age Ancestors

 From SciTechDaily:

In a paper published in the Yearbook of the American Physical Anthropology Association, Dr. Miki Ben-Dor and Prof. Ran Barkai of the Jacob M. Alkov Department of Archaeology at Tel Aviv University, together with Raphael Sirtoli of Portugal, show that humans were an apex predator for about two million years. Only the extinction of larger animals (megafauna) in various parts of the world, and the decline of animal food sources toward the end of the stone age, led humans to gradually increase the vegetable element in their nutrition, until finally they had no choice but to domesticate both plants and animals — and became farmers.

“So far, attempts to reconstruct the diet of stone-age humans were mostly based on comparisons to 20th century hunter-gatherer societies,” explains Dr. Ben-Dor. “This comparison is futile, however, because two million years ago hunter-gatherer societies could hunt and consume elephants and other large animals — while today’s hunter gatherers do not have access to such bounty. The entire ecosystem has changed, and conditions cannot be compared. We decided to use other methods to reconstruct the diet of stone-age humans: to examine the memory preserved in our own bodies, our metabolism, genetics, and physical build. Human behavior changes rapidly, but evolution is slow. The body remembers.” (Read more.)

 From Science News:

When some of the earliest human migrants to Europe encountered Neandertals already living there around 45,000 years ago, hookups flourished.

Analyses of DNA found in human fossils from around that time — the oldest known human remains in Europe — suggest that interbreeding between Homo sapiens and Neandertals, who were on the fast track to extinction, occurred more commonly than has often been assumed, two new studies suggest.

Genetic evidence in the new reports indicates for the first time that distinct human populations reached Europe shortly after 50,000 years ago. Neandertals interbred with all the groups detected so far, ensuring that some of their genes live on today in our DNA.

Remains of three H. sapiens individuals unearthed in Bulgaria’s Bacho Kiro Cave yielded nuclear DNA containing Neandertal contributions of about 3 to 4 percent, evolutionary geneticist Mateja Hajdinjak of the Francis Crick Institute in London and colleagues report April 7 in Nature. The ancient DNA came from a tooth and two bone fragments radiocarbon dated to between around 43,000 and 46,000 years ago. Stone tools typical of late Stone Age humans were found in the same sediment as the fossils. (Read more.)

From Science:

Bones and teeth are important sources of Pleistocene hominin DNA, but are rarely recovered at archaeological sites. Mitochondrial DNA has been retrieved from cave sediments, but provides limited value for studying population relationships. We therefore developed methods for the enrichment and analysis of nuclear DNA from sediments, and applied them to cave deposits in western Europe and southern Siberia dated to between approximately 200,000 and 50,000 years ago. We detect a population replacement in northern Spain approximately 100,000 years ago, accompanied by a turnover of mitochondrial DNA. We also identify two radiation events in Neanderthal history during the early part of the Late Pleistocene. Our work lays the ground for studying the population history of ancient hominins from trace amounts of nuclear DNA in sediments. (Read more.) 

From Atlas Obscura:

The more than 10,000 animal bones excavated from the site so far include at least 50 mammal species that reflect the region’s position at the crossroads of three continents: rhinoceros, elephants, deer, ostriches, and horses. And oh so many carnivores: the coyote-sized Etruscan wolf, two species of saber-toothed cat, lynx, bears, giant hyenas, the lion-sized European jaguar, and the ecosystem’s fearsome apex predator, Acinonyx pardinensis, a giant cheetah.

“Dmanisi has the strangest fauna,” says Ferring. It suggests, he says, “you’re looking at a patchwork of forest and grassland. There was something there for everybody, which explains the diversity.”

In this carnivore-rich ecosystem, the early humans were more likely scavengers than hunters—and also sometimes dinner. Some of the animal bones show signs that the hominins butchered them, slicing off meat with stone tools, and some of the hominin bones have gnaw marks. Ferring believes that resource-rich Dmanisi may have been a good spot for a carnivore to raise a family. There is evidence that many of the bones were deposited in burrows dug by animals or in natural, nest-like folds in the promontory’s basalt. “The carnivores found the perfect place for denning, which means they were bringing food to their young,” he says. (Read more.) 


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