Ian Sample “Neanderthals live on in DNA of humans” http://www.guardian.co.uk/science/2010/may/06/neanderthals-dna-humans-genome
Most people living outside Africa can trace up to 4% of their DNA to a Neanderthal origin, a consequence of interbreeding between the two groups after the great migration from the contintent(sic.).
Anthropologists have long speculated that early humans may have mated with Neanderthals, but the latest study provides the strongest evidence so far, suggesting that such encounters took place around 60,000 years ago in the Fertile Crescent region of the Middle East.
Small, pioneering groups of modern humans began to leave Africa 80,000 years ago and reached land occupied by the Neanderthals as they spread into Eurasia. The two may have lived alongside each other in small groups until the Neanderthals died out 30,000 years ago.
To see how similar the Neanderthal was to modern humans, the team compared the ancient DNA with the genomes of five people from France, China, southern Africa, western Africa and Papua New Guinea. The study is the first to attempt a whole-genome comparison between Neanderthals and modern humans.
The researchers found that modern humans and Neanderthals shared 99.7% of their DNA, which was inherited from a common ancestor 400,000 years ago. Further analysis revealed that Neanderthals were more closely related to modern humans who left Africa than to the descendants of those who stayed. Between 1% and 4% of the DNA in modern Europeans, Asians and those as far afield as Papua New Guinea, was inherited from Neanderthals.