I heard this about a year ago but just saw it on NOVA July 2015. We have one to three percent Neanderthal in our DNA. The only people that have no Neanderthal DNA are sub-sierra Africans. None.
So, this begs the question, 'Why did Neanderthals decide to mate with Cro-Magnum and not Africans?
I believe this is instinctive. The Neanderthals were an intelligent species, as were the Cro-Magnum, where we come from. If not for this interbreeding between Mangum and Neanderthals, we probably would not have survived.
Just something to think about.