The BBC website has a fascinating article on a scientific study of human ancestry that strongly supports the notion that all humans come from Africa — and that at some point in the past there was some interbreeding between Homo sapiens and Neanderthals. The evidence of interbreeding is found in many of us, because humans of Eurasian stock carry a small percentage of Neanderthal genes.
The conclusions are the result of a four-year study, in which numerous universities from around the world participated, that sought to sequence Neanderthal genomes. The project suggests that a hardy band of humans left Africa between 50,000 and 60,000 years ago, did some limited interbreeding with Neanderthals, and then spread across the globe, eventually reaching and populating every continent. The fact of interbreeding should not be surprising, because the fossil record indicates that humans and Neanderthals lived together in Europe for some 10,000 years, before Neanderthals died out.