Neanderthals were the stocky, low-browed hunters who dominated Europe until 30,000 years ago. They died out and were believed to have been replaced by modern humans, though the two species did live side by side for about 14,000 years. Now it looks like that Neanderthals and modern humans may have interbred. The New York Times reports that Neanderthals not only mated with humans – they left their print on the modern human genome.

Scientists have been working to decode the Neanderthal genome for quite some time and are believed to be 60 percent there. Biologists have been extracting the fragments of DNA from Neanderthal fossil bones. They recently reported the first detailed analysis of the Neanderthal genetic sequence. And the findings were surprising to biologists. The team compared parts of the Neanderthal genome with those of different modern humans. They discovered that about 1 percent to 4 percent of the genome of non-Africans today comes from Neanderthals. Neanderthals and modern humans are believed to have split species around 600,000 years ago.

The biologists have found that the Neanderthal DNA does not seem to have played a great role in human evolution. The team has identified just 100 genes that have contributed to the evolution of modern humans since the split. Biologists believe that these genes are significant for bone structure and cognitive function.

Nonetheless, biologists are extremely excited about the findings. Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, is the lead biologist on this new discovery. As Paabo announced at a news conference, “Seven years ago, I really thought that it would remain impossible in my lifetime to sequence the whole Neanderthal genome.”

But the idea that Neanderthals and humans actually interbred is being met with trepidation by archeologists. Some archeologists think that interbreeding happened in the Middle East, not Europe. Further, they feel interbreeding happened around 100,000 to 60,000 years ago. Archeologists also feel, as reported by the New York Times, that geneticists “depend heavily on complex mathematical statistics that make their arguments hard to follow. And the statistical insights, however informative, do not have the solidity of an archaeological fact.”

But Paabo and his colleagues feel that their discovery disproves the “out of Africa” idea that everyone comes from the same population in Africa. Further, they feel that Neanderthals intermixed only with the people who left Africa. This concludes that only non-Africans drew from a second gene pool.

For further reading:

Modern humans and Neanderthals likely mated
New evidence shows that some Neanderthals have left their imprint on the human genome.