Genetic diversity within continental races, including that of Sub-Saharan Africans, are mostly a consequence of genetic drift.
While genetic diversity between races are from selection. Thus the inter-racial genetic differences are more likely to manifest in trait differences that humans find more meaningful (which I use purely in a descriptive manner, not prescriptive), such as physiological (medical, metabolic), psychological & behavioral (personality), cognitive (intelligence), and of course physical (appearance, athletic).
The intra-racial differences that arise from genetic drift result in things that are still tangible genetic differences, e.g. ABO blood group frequencies, but don't map well onto characteristics that human societies place emphasis on as much.
And to address your point that:
>The genetic diversity of "black" alone exceeds the rest of the world combined.
This is because the level of genetic diversity as influenced by genetic drift is primarily a function of population size, and Africa being the origin of the Homo sapien species, and probably the Homo genus as a whole, has always had the highest level of effective population size. Thus genetic drift in Africans is least likely to be able to cause allele fixation on particular genes, and so such diversity is better preserved. But as already mentioned, these forms of genetic diversity is less likely to impact the observed traits that most humans, both academics/social scientists and your average joe, find "meaningful".
While genetic diversity between races are from selection. Thus the inter-racial genetic differences are more likely to manifest in trait differences that humans find more meaningful (which I use purely in a descriptive manner, not prescriptive), such as physiological (medical, metabolic), psychological & behavioral (personality), cognitive (intelligence), and of course physical (appearance, athletic).
The intra-racial differences that arise from genetic drift result in things that are still tangible genetic differences, e.g. ABO blood group frequencies, but don't map well onto characteristics that human societies place emphasis on as much.
And to address your point that:
>The genetic diversity of "black" alone exceeds the rest of the world combined.
This is because the level of genetic diversity as influenced by genetic drift is primarily a function of population size, and Africa being the origin of the Homo sapien species, and probably the Homo genus as a whole, has always had the highest level of effective population size. Thus genetic drift in Africans is least likely to be able to cause allele fixation on particular genes, and so such diversity is better preserved. But as already mentioned, these forms of genetic diversity is less likely to impact the observed traits that most humans, both academics/social scientists and your average joe, find "meaningful".