Neanderthals in Europe Died Out Thousands of Years Sooner Than Some Thought, Study Says,2014

Neanderthals in Europe Died Out Thousands of Years Sooner Than Some Thought, Study SaysThe new york time

The finding, aided by advances in radiocarbon dating, sharply narrows the period in which Neanderthals and modern humans overlapped in Europe.

Neanderthals, our heavy-browed relatives, spread out across Europe and Asia about 200,000 years ago. But when did they die out, giving way to modern humans?

A new analysis of Neanderthal sites from Spain to Russia provides the most definitive answer yet: about 40,000 years ago, at least in Europe.
 humans spread outward.
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The Neanderthal Inside Us
The Neanderthal Inside Us

Svante Paabo is a Swedish biologist who studies evolutionary genetics.
Video Credit By Erik Olsen on Publish Date June 23, 2014. Image CreditDavid Reich/Nature

“This is a very strong compilation,” said Chris Stringer, who leads research on human origins at the Natural History Museum in London and who was not involved in the research. “I think it kind of replaces the picture we had before.”

In 1995, researchers including Jean-Jacques Hublin, now at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, announced fossil evidence of Neanderthals living 30,000 years ago in a cave near the southern Spanish city of Málaga.

Dr. Hublin said he had changed his mind as better radiocarbon dates became available. “To me, I’m ready to buy the new date,” he said.

Modern humans migrated out of Africa at least 60,000 years ago, and anthropologists have been trying to figure out what happened when the two groups encountered each other.

One of the reasons some researchers think Neanderthals survived longer on the Iberian peninsula is that there are no signs of modern humans living there at that time.

A recent analysis of Neanderthal DNA shows that Neanderthals and modern humans not only crossed paths, but interbred. For non-African people living today, 1 to 4 percent of their genome has Neanderthal origins.

The genetics suggest that interbreeding occurred about 50,000 to 60,000 years ago, somewhere in western Asia.

“You’ve kind of got two parts of the story,” Dr. Stringer said. “There must have been a western Asia coexistence, which included interbreeding. Then there was a later coexistence in Europe, for which we have no evidence of interbreeding but possible evidence of some cultural contact between the groups.”

Dr. Higham, the lead author of the Nature paper, and his colleagues took advantage of advances in radiocarbon dating in testing samples of bone, charcoal and shell from 40 sites, mostly in Western Europe. The dating method takes advantage of unstable, radioactive carbon 14 atoms produced from the bombardment of the atmosphere by cosmic rays from outer space. The radioactive carbon combines with oxygen atoms to form carbon dioxide, and plants and animals take up some of it as long as they are alive.
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But when they die, they absorb no additional radioactive carbon, and the carbon 14 disappears over time. The ratio of carbon 14 to carbon 12, which is stable, thus tells the age and can be used to date bones and artifacts up to about 50,000 years ago.

Contaminants containing younger organic molecules can distort the dating. Dr. Higham said just 1 percent of modern carbon infiltrating a 50,000-year-old fossil would make it look 7,000 to 8,000 years younger. The researchers prepared samples that would extract collagen in the bone and remove the contaminants.

“What we find is often the dates get older,” Dr. Higham said. “We’ve managed to chip away at these erroneous younger Neanderthal dates to come up with a more refined, and we think accurate, estimate for when Neanderthals disappeared.”

Dr. Higham said his team would like to expand the research to Neanderthal sites in Eastern Europe and across Russia to Siberia. It is possible that Neanderthals survived later in those areas.

Some of the conclusions are tentative because many of the sites do not have bones of the actual inhabitants, and paleontologists are still debating whether it was Neanderthals or modern humans who made the tools found at some sites.

“This gives us a framework, basically, which allows us to ask more interesting questions,” said William Davies of the University of Southampton in England, who wrote an accompanying commentary in Nature. “About what the tools might mean, how they were used, what they tell us about Neanderthal interactions.”

The findings so far indicate that Neanderthals did not disappear all at once.

“I think we’ll see patchy disappearance prior to extinction,” Dr. Higham said.

A version of this article appears in print on August 21, 2014, on page A11 of the New York edition with the headline: New Estimate on Demise of Neanderthals in Europe. Order Reprints|Today's Paper|Subscribe

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