I know that there is higher genetic diversity in Africa, and lower genetic diversity in non-African populations. That doesn't mean that there is greater differe

I know that there is higher genetic diversity in Africa, and lower genetic diversity in non-African populations. That doesn't mean that there is greater difference between Africans and other Africans than between Africans and non-Africans; that only means there is greater difference between Africans and other Africans, than there is between non-Africans and other non-Africans. To put it another way: there is extremely low genetic diversity in peregrine falcons; housecats have much higher diversity. But the two most-different individuals, when taken from a sample that contains both housecats and peregrine falcons, will certainly be a housecat and a peregrine falcon. Despite falcons having lower genetic diversity, they are still more-different from a housecat than any given housecat is from another. Of course, humans are the same species, so it won't be as dramatic. But high genetic diversity amongst sub-Saharan African populations doesn't mean that sub-Saharan Africans are more different from each other than they are from East Asians (for example) — it only means they're more different from each other, than East Asians are from other East Asians. Pick any two people in China, and they're probably pretty genetically similar; pick any two people in sub-Saharan Africa, and they're probably pretty genetically different. That doesn't imply anything about how different the two Chinese people are from the two African people. Additionally, non-sub-Saharan populations typically have some non-Homo-Sapiens ancestry: Neanderthal and Denisovan, for East Asians, and just Neanderthal, for Europeans. While genetic diversity within those groups is low, it doesn't mean that genetic distance from any given sub-Saharan group is low.