Everyone should read Erectus Walks Amongst Us. It's very good.
Human fossils are rare because the conditions needed to preserve them are rare. 1 Early humans did not bury their dead, so animals, decomposition, and the weather soon erased all traces of them. To be preserved, a body must be buried soon (hours, days, or months, depending on circumstances) after death in a way that excludes oxygen. This can happen if a catastrophic event, such as a volcanic eruption, a landslide, or a flash flood caused the death, or the person dies in a river that is depositing silt. So, if non-Africans were the first moderns, but did not die in areas where preservation was likely, an early African skull may not be from the first modern humans. Also, northern Africa is, and was, quite accessible to Eurasians and, as we shall see in Section IV, it is likely that modern humans arose outside of Africa, then migrated in to Africa, where they and their descendants died.
Where their descendants mixed, more likely. My guess is that hss humans migrated into Africa where they mated with the primitive descendants of hominid-like creatures such as Lucy and Rhodesia "man", who were neither human or ape. This resulted in the Negro Race, which by all measure is a primitive race of human. That would explain a lot about natural African behavior (the propensity to steal, rape and murder) and their lower intelligence.
Negros are, basically, modern Australopithecus with a boost from Eurasian genes. Just my wild theory.