That was my thought too, if I had to venture a guess as prolific as people are, any species that we could have interbred with are already part of us and you'd b

That was my thought too, if I had to venture a guess as prolific as people are, any species that we could have interbred with are already part of us and you'd be able to find it on the genome just as we have neanderthals. That's probably the best way at this point to test for it, if it's there or not.