Neanderthals survived for thousands of years longer than scientists thought, with small lingering bands finding refuge in a massive cave near the southern tip of Spain, new research suggests.
The work contends that Neanderthals were using a cave in Gibraltar at least 2,000 years later than their presence had been firmly documented anywhere before, researchers said.
"Maybe these are the last ones," said Clive Finlayson of the Gibraltar Museum, who reported the findings Wednesday with colleagues on the website of the journal Nature.
The paper says charcoal samples from fires that Neanderthals set in the cave are no older than 28,000 years and may be only 24,000 years old.
But experts are divided on how strong a case made by the paper, called Late Survival of Neanderthals at the Southernmost Extreme of Europe.
Eric Delson of Lehman College in the Bronx and the American Museum of Natural History, who did not participate in the research, said the paper's 28,000-year-old date seems secure but that its case for Neanderthal presence after that is shaky.
Even the older date is the only clear evidence of Neanderthals anywhere after 30,000 years ago, he said. But there have been prior claims of "the last Neanderthal" that were eventually shot down, and whether this one will hold up remains to be seen, he said.
Last days of Neanderthals a lingering mystery
Neanderthals were stocky, muscular hunters in Europe and western Asia who appeared more than 200,000 years ago. They died out after anatomically modern humans arrived in Europe some 35,000 to 40,000 years ago and spread west into Neanderthal territory.
Scientists have long been fascinated by the last days of the Neanderthals.
Were they doomed because they couldn't compete with the encroaching modern humans for resources, or because they caught new germs from the moderns, or because of climate change?
Did the two groups have much contact, and what kind?
Neanderthals, moderns likely didn't meet
They didn't appear to encounter each other in Gibraltar at Gorham's Cave.
More than 5,000 years separate the last traces of the Neanderthals from the earliest evidence of modern humans, Finlayson said.
He believes the area near the cave contained small bands of Neanderthals and of advancing moderns at the same time, but over a large and varied landscape. So it's not clear whether the two groups ever met, he said.
The Neanderthals probably roamed a large area and used the cave periodically as a place to cook, eat and sleep, he said. The cave has yielded butchered bones of such animals as wild goat and deer, and remains of mussels and shellfish.
At the time of the Neanderthals, the Mediterranean was about three miles away; rising sea level has since brought the water to within a few dozen yards.
Experts said the region is a likely place to find the last vestiges of Neanderthals, because it's the tip of a geographic cul-de-sac that leads away from central Europe.
Experts question age
Paul Mellars, a professor of prehistory and human evolution at Cambridge University, said he believes the range of radiocarbon dating evidence in the paper suggests ages more like 31,000 or 32,000 years for the charcoal.
Contamination by younger material might have skewed some radiocarbon results toward more recent dates, he observed.
Even with the older dates, the paper would be important because it would represent one of the last Neanderthal occupations in Europe, he said.
But paleoanthropologist Richard Klein of Stanford University said it's questionable whether the charcoal fragments really date Neanderthal presence.
Neanderthal artifacts appear to be sparsely distributed in the deposit, and their spatial relationship to the charcoal needs to be specified more clearly, he said.
Finlayson said he's comfortable with the 24,000-year figure and called the 28,000-year estimate conservative. There's no evidence of contamination with younger material and chemical analysis argues against it, he said.
As for the Neanderthal artifacts, he said, their location within the excavated site shows they're associated with the dated charcoal. And there aren't any artifacts from modern humans associated with the charcoal, he said.