it seems there were very few Neanderthals or humans around in Europe (https://en.wikipedia.org/wiki/Neanderthal#Population https://en.wikipedia.org/wiki/Neander

it seems there were very few Neanderthals or humans around in Europe (https://en.wikipedia.org/wiki/Neanderthal#Population https://en.wikipedia.org/wiki/Neanderthal#Population: “Like modern humans, Neanderthals probably descended from a very small population with an effective population—the number of individuals who can bear or father children—of 3,000 to 12,000 approximately. However, Neanderthals maintained this very low population, proliferating weakly harmful genes due to the reduced effectivity of natural selection”) Given that Neanderthals were found from Spain to Libanon and even deep into Asia, chances are most humans never saw Neanderthals or vice versa. Also, I don’t see how that article counts interspecies sex, pregnancies or even live births. It counts number of births who grew up to reproduce. I can easily see early humans stigmatizing or even killing kids of mixed descent or, even easier, children from such encounters being less fertile or even infertile.