That "early humans and Neanderthals " _could_ "mix" , mate and produce fertile offspring , means they were the same species by the perfect definition of "same species" : ability to mate and produce fertile offspring . Neanderthals were Homo sapiens Neanderthals same species as us , Homo sapiens sapiens.

That "early humans and Neanderthals " _could_ "mix" , mate and produce fertile offspring , means they were the same species by the perfect definition of "same species" : ability to mate and produce fertile offspring . Neanderthals were Homo sapiens Neanderthals same species as us , Homo sapiens sapiens.