Yeah, I know the interaction between proto-humans and Neanderthals has been the subject of a lot of fiction, but I've always felt that paleontologist Björn Kurtén's Dance of the Tiger was the best—not least for its tender/hot scenes of Cro-Magnon/Neanderthal sex. Dance speculated that Neanderthals did not so much die out as much as become "bred out." Kurtén called Dance "paleo-fiction" because he was convinced things must have developed along the lines he proposed, but he lacked a fossil record confirming it.

Maybe that evidence was just discovered down a rabbit hole in Portugal.