Nah, the human species fucks each other too much, even in the most extreme cases of segregation. The Neanderthal-Human divide is a weird case that supports some idea of a diversity gulf...except I don't think you want to jump to the species level. Anyhow, the idea of qualitative differences based on ethnicity is one of those persistant racial biases in science, & one that has been thoroughly put down time & time again; maybe it is the Franz Boas admirer in me, but I don't cotton to it. I say: it IS a huge leap, & it is one the breaks the suspension of disbelief for me.