There is a little Neanderthal in nearly all of us, according to scientists who compared the genetic makeup of humans with that of our closest ancient relatives.
Most people living outside Africa can trace up to four per cent of their DNA to a Neanderthal origin, a consequence of interbreeding between the two groups after the great migration from the contintent.
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 West Asia.
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.
Scientists led by Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig took four years to sequence the whole Neanderthal genome from powdered bone fragments taken from three females who lived in Europe 40,000 years ago.
The researchers found that modern humans and Neanderthals shared 99.7 per cent 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.