Wednesday, June 24, 2015

Neanderthals Interbred with Modern Humans

What happened to the Neanderthals, that now-extinct group of stocky, big-boned ancient humans who lived in Europe and Asia until about 30,000 years ago? Were they wiped out by conflict with modern humans who arrived later in Europe or by some other unfavorable environmental condition? Did they interbreed with modern humans, ultimately "disappearing" as a distinct group because their genes were incorporated into a much larger gene pool of modern humans?

Several years ago I reported (this blog May 12, 2010) that Neanderthals shared a number of genetic variations with modern Europeans that they did not share with modern Africans. These findings at least suggested, but did not prove, that interbreeding occurred when Neanderthals met modern humans.

More recently, DNA analysis reveals that up to 3% of the DNA of modern Eurasians is similar to the DNA of the Neanderthals. And according to a paper published this week in Nature, DNA analysis of a bone of a modern human who lived in present-day Romania around 40,000 years ago revealed that 6-9% of his genes were from Neanderthals. In other words, he may have had a great, great-grandparent who was a Neanderthal.

Of course, this does not prove that interbreeding was the cause of the disappearance of the Neanderthals. Interbreeding can occur between groups in conflict, as the behavior of modern-day humans clearly shows. But at least it indicates that interbreeding did occur, at least occasionally.

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