[adorno]

I think in this case interbreeding species to create “Mules” might come to mind as a comparison?

But, did the the Neanderthal/Homo Sapiens relationships yield any offspring capable of further offspring?

If so, the comparison to the mule is not correct. If offspring were capable of reproducing further, then, Neanderthals and Homo sapiens were of the same species.

[Openurmind]

I’m going to guess most could not, or there was an extremely high infant mortality rate and just a few reproductions and births actually resulted. We are talking about a time line of tens of thousands of years. If given that amount of time to adapt and evolve, Mules might become fertile and be able to also reproduce at sometime in the future.