Interbred? How so?
If early Homo Sapiens bred with others, and they produced others, then, they were of the same “species”, meaning, they were all of the human species. Never mind calling the Neanderthals or Denisovans or Africans or whatever; they were all of the same species of animals.
Probably alcohol....................
Do you honestly think that wolves, coyotes, and dogs are the same?