the-BA : Neanderthals not killed

By Claire Witham

"Abrupt climate change was not responsible for Neanderthal demise," said Dr Katerina Harvati who presented novel research at the BA Festival of Science on Wednesday.

One of the hot debates in science is whether Neanderthal man died out because of competition with modern humans or because of a colder climate. Dr Harvati's result flies in the face of other research that says Neanderthals had to face the worst weather conditions of the last 250,000 years.

Harvati suggests that, instead of having a direct role in the extinction, colder temperatures in Northern Europe may have caused Neanderthals to migrate further south. This would have increased population levels and intensified competition for land and food.

"Their extinction could have been due to competition with modern humans," said Dr Harvati from the Max Planck Institute for Evolutionary Anthropology in Leipzig.

The study, published in this week's Nature, focuses on Gorham's Cave in Gibraltar. This was the home of the last surviving Neanderthals.

Radiocarbon dates from archaeological remains in the cave were compared to those from environmental deposits dug up in the seas off Venezuela. These deposits show what changes in climate were occurring at the time of the extinction.

"This new method enables us to assess the climatic background at the time of the Neanderthal extinction much more accurately than was previously possible," explained Dr Harvati.

Her method avoids problems with conventional radiocarbon dating of artefacts from this time that are experienced in other studies.

"Our approach goes straight from radiocarbon years to climate," she said.

Three possible dates for the extinction of Neanderthal man have been proposed. These are 30,000 BC, 26,000 BC and 22,000 BC. Climates at the earliest two dates were not particularly different from the rest of the last glacial period, which was generally climatically unstable. This means that the climate wouldn’t have played a role in extinction at either of these times.

The 22,000 BC date is much more controversial and places the end of the Neanderthals just before a major environmental change. Ice sheets expanded and cold conditions set in across much of northern Europe. But Gibraltar's climate would have remained unaffected, due to warmer waters off the coast.

The study, led by Polychronis Tzedakis at the University of Leeds, eliminates sudden catastrophic climate change as the cause of the Neanderthal extinction, but does not provide the final explanation as to what caused their disappearance.

Other possibilities include direct or indirect competition with modern humans, disease, and demographic changes.

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