While this might not sound like much, we don’t all have the same bits of Neanderthal DNA and when we pool all these gene variants they account for about 40 percent of the Neanderthal genome[53]—providing incontrovertible evidence that the two species not only met, but had sex and reproduced. Neanderthal males coupled up with Homo sapiens females and vice versa.[54] Interbreeding happened over tens of thousands of years, but the most active period of mating was between about 50,000 and 60,000 years ago.[55]
