Parent said: > As I understand it, all Neanderthal genetics that modern man has came in through the X chromosome. This could indicate that male offspring of Ne

Parent said: > As I understand it, all Neanderthal genetics that modern man has came in through the X chromosome. This could indicate that male offspring of Neanderthals and Homosapiens were infertile, which would be a cut-and-dry indicator that they're two separate species. Castration is an alternative (or additional) explanation.