Even in the modern "out of Africa" hypothesis, it is accepted that different groups interbred with Neanderthals, Denisovans, etc. that weren't part of the "out of Africa" group. So, as far as I can tell, even the most monogenic scientific view is only partially monogenic, since it only claims that we share some common descent from an original African homo sapien, but not our entire descent. Regardless, if we were not talking about humans, the debate would be nearly pointless. We are so genetically distant, morphologically different, and tend toward such predictably different social structure and average behavior, that if we were talking about any other organism, we would unquestionably be talking about at least different sub-species. Probably different species, despite the outdated, unscientific, colloquial idea that anyone who can produce fertile offspring are the same species. In any case, the evidence is strongly against a pure monogenic hypothesis, and there's no conclusive evidence against a polygenic hypothesis. It is purely the cultural zeitgeist which prevents us from honestly considering polygenism.