By comparing sections of Neanderthal DNA with sections of DNA in modern humans that we think have come from Neanderthals, we can build up a very finely tuned model of the success, from an evolutionary point of view, of these hybridizations. When Graham Coop and his colleagues did this, they found that our genomes are slowly purging themselves of Neanderthal DNA, which suggests that these matings were not to our advantage, but not massively disadvantageous. Our DNA around Neanderthal chunks is undergoing weak negative selection,
