And Africa has the least amount of human progress and probably more preservation opportunity. The white sands footprints are throwing a major wrench into human migration theories as well.
We also see this among animals that evolved to evade humans (in Africa and to some extent Eurasia) and those that didn't - in the Americas and Australia.
Also genetically we are one species down to the genetic level. But the MOST divergent people, genetically speaking, are the Khoi-San (Bushmen) -- they are genetically more distinct from West Africans than those West Africans are from Irish people
The "Out of Africa" hypothesis seems valid so far - note that this means NOTHING in terms of modern-day peoples.
Clearly, that is quite obvious.
One only needs to read the Bell Curve to understand Herrnstein and Murray's explanation of why that is so true.