Sleeping with the Other

Advances in the study of ancient DNA have led to the finding that modern non-African humans have 1-2% of our DNA coming from Neanderthals, and the Neanderthals also had human DNA.

This exchange, the scientists conclude, took place about 100,000 years ago. That’s a puzzling date, because a great deal of evidence indicates that the ancestors of today’s non-Africans did not expand out of Africa until 50,000 to 60,000 years ago.

 Neanderthals are either a closely related species, or subspecies of our own Homo sapiens.  They split off from the last common ancestor about 600,000 years ago, and left African for Europe.   Studies suggest they had a distinct culture including the burial of the dead.

And these genes have effects on our health:

Snippets of Neanderthal DNA contribute to the contemporary risk for myriad ills, including heart attack, nicotine addiction and mood disorders as well as incontinence, foot callouses and precancerous skin lesions.

The identification of these sequences is made because they exist in the Neanderthal genome, and not in the genomes of Africans.

So, you have to wonder;  how did it happen?  what sort of communication occurred between these different groups of early humans that they interbred, and did so sufficiently to leave permanent records in the genomes of both?

I mean, we can't even get along with one another.