10 may 2011

New evidence for when Neanderthals died out


Radiocarbon accelerator unit
Improved methods of dating are directed by the Oxford Radiocarbon Accelerator Unit

Direct dating of a fossil of a Neanderthal infant suggests that Neanderthals probably died out earlier than previously thought.

Researchers have dated a Neanderthal fossil discovered in a significant cave site in Russia in the northern Caucasus, and found it to be 10,000 years older than previous research had suggested. This new evidence throws into doubt the theory that Neanderthals and modern humans interacted for thousands of years. Instead, the researchers believe any co-existence between Neanderthals and modern humans is likely to have been much more restricted, perhaps a few hundred years. It could even mean that in some areas Neanderthals had become extinct before anatomically modern humans moved out of Africa.

The research, directed by the University of Oxford and University College Cork in collaboration with the Laboratory of Prehistory at St Petersburg, Russia, and funded by Science Foundation Ireland is published today in PNAS Online Early Edition. The research centres on Mezmaiskaya Cave, a key site in the northern Caucasus within European Russia, where the team directly dated the fossil of a late Neanderthal infant from the Late Middle Paleolithic layer and a series of associated animal bones. They found that the fossil was 39,700 years old, which implies that Neanderthals did not survive at the cave site beyond this time. 

This finding challenges previous claims that late Neanderthals survived until 30,000 years ago in the northern Caucasus, meaning that late Neanderthals and modern humans were not likely to experience any significant period of co-existence.

The new dating evidence throws new light on when the Neanderthals became extinct and why. The research team believes that Neanderthals died out when the modern humans arrived or that they had already become extinct before then, possibly because of climate change, dwindling resources, or other scenarios.

The research suggests that if we are to have accurate chronologies the data needs to be revised, improved and corrected so possible associations between Neanderthal extinctions, dispersals of early modern humans and climatic events can be properly assessed. Previous dating processes seem to have ‘systemically underestimated’ the true age of Late Middle Paleolithic and Early Upper Paleolithic deposits, artifacts and fossils by up to several thousand years, says the paper.

The latest dating techniques mean we can purify the collagen extracted from tiny fragments of fossil very effectively without contaminating it

Dr Tom Higham

Co-author of the paper Dr Tom Higham, Deputy Director of the Oxford Radiocarbon Accelerator Unit, said: ‘The latest dating techniques mean we can purify the collagen extracted from tiny fragments of fossil very effectively without contaminating it. Previously, research teams have provided younger dates which we now know are not robust, possibly because the fossil has become contaminated with more modern particles. This latest dating evidence sheds further light on the extinction dates for Neanderthals in this key region, which is seen by many as a crossroads for the movement of modern humans into the wider Russian plains. The extinction of Neanderthals here is, therefore, an indicator we think, of when that first probably happened.’

Lead author Dr Ron Pinhasi, from University College Cork, said: ‘It now seems much clearer that Neanderthals and anatomically modern humans did not co-exist in the Caucasus, and it is possible that this scenario is also true for most regions of Europe. Many of the previous dates for late Neanderthal occupation or sites across Europe are problematic. This is simply an outcome of the fact that the association between the dated material and late Neanderthals is not always clear because we cannot always be certain whether archaeological stone tool assemblages, such as the Mousterian, that has been attributed in the case of Europe to Neanderthals, was not in some cases actually produced by modern humans. We have to directly date Neanderthal and anatomically modern human fossils to resolve this.’