Rolf Quam, a Binghamton University anthropologist and member of an international research team, says study of ancient DNA suggests it wasn't competition from modern humans that caused Neanderthals to start disappearing in Western Europe around 30,000 years ago.
"The Neanderthals are our closest fossil relatives and abundant evidence of their lifeways and skeletal remains has been found at many sites across Europe and western Asia," he said. "Until modern humans arrived on the scene, it was widely thought that Europe had been populated by a relatively stable Neanderthal population for hundreds of thousands of years.
"Our research suggests otherwise and, in light of these new results, this long-held theory now faces scrutiny."
Their DNA analysis showed Neanderthal individuals from Western Europe show an extremely reduced amount of genetic variation, less even than the present-day population of remote Iceland, beginning about 50,000 years ago, the researchers said.
The finding suggests Western European Neanderthals went through a demographic crisis, a population bottleneck that severely reduced their numbers, leaving Western Europe largely empty of humans for a period of time, they said.
"The fact that Neanderthals in Western Europe were nearly extinct, but then recovered long before they came into contact with modern humans came as a complete surprise to us," Love Dalen at the Swedish Museum of Natural History in Stockholm said. "This indicates that the Neanderthals may have been more sensitive to the dramatic climate changes that took place in the last Ice Age than was previously thought."
Quam said he agreed.
"It may very well have been the case that the European Neanderthal populations were already demographically stressed when modern humans showed up on the scene," he said.