One of my many sketches featuring different species of humanity. Species, not races. Any interbreeding would have result in sterile children. I’m fascinated with the idea that Homo Sapiens is just one of, perhaps, many forms of human beings. What would the world have looked like if the other species had not died out?
Would the child of a human & a chimp be infertile? Nobody really knows. Lots of species can interbreed but choose not to, which is what makes them functionally separate.
If the races actually refrained from interbreeding there would eventually be separate human species. Despite violent coercion, no separated human populations, once connected, have refrained. One might say the violent coercion was one aspect of the interbreeding.
Still, it is interesting contemplating the Africa that supposedly existed once upon a time — an Africa with several different, closely related great ape & hominid species. How human were they?
Have you ever heard of someone trying to interbreed different subspecies of chimps or gorillas? Or interbreed chimps and bonobos?