The science on the question of whether modern Homo sapiens interbred with Neanderthals, or came out of Africa and overran their cousins, has gone back and forth a few times over the years. In fact, I was just talking about this with someone at the Beltane festival over the weekend. (One gets into the most interesting discussions at Pagan gatherings -- ritual magic, evolutionary biology, BDSM, technogeekery, martial arts...)
When I look in the mirror and see my brow ridge, and feel that bit of an occipital bun on the back of my head, it seems sensible to me that my umpity-great grandpappy might have passed on a few genes from the Neanderthal part of the family tree, but -- I said a few days ago -- the evidence wasn't really there.
Well, now it is. Recent analysis of the Neanderthal genome, from bone fragements, reveals that those of us whose ancestral group developed outside Africa, may have from 1 to 4 percent of their genome from Neanderthal ancestors.
David Reich, a geneticist at Harvard Medical School, notes that this implies that "Neanderthals aren't quite extinct. [They] all live on a little bit in many of us."