I know that there are hints of a “bottle neck” in the human population in the ancient past. Probably, Ice Age climate change caused humans to drop down to less than 10K and perhaps as few as a few hundred world wide.
A smaller base population in the colder climates of Europe would cause less diversity there. Some have suggested that this also caused selection for higher intelligence and other cultural and genetic changes in order to survive the near extintion level conditions.
This is esoteric and highly speculative stuff. Trying to read into it is tough, and not exactly responsible science.
However, I think it is interesting to bring up that we all evolved from an original African population.
Ultimately the human species originated in Africa.
The discussions center around the when and how.