It seems we were genetically incompatible with our ancient relatives – and male fetuses conceived through sex with Neanderthal males would have miscarried. We knew that some cross-breeding between us and Neanderthals happened more recently – around 100,000 to 60,000 years ago. - in https://www.newscientist.com/article/2083381-missing-y-chromosome-kept-us-apart-from-neanderthals/
