Geeks and Freaks
Probably the most usual way race is identified is by skin color. Of course there are a number of dark skinned peoples in the world who aren't especially related: Africans, Australian natives, Melanesians, and some South Asians. It's also true that Africans as a group have more genetic diversity than the rest of the world combined.
However, ancestry related differences are not imaginary. About one third of the humans, mainly from Europe, the Middle East and parts of Africa, have adult lactase persistence - the ability to digest milk sugar as adults. Not coincidentally, this reflects ancestral keeping of milk producing livestock. Tibetans and Andean Indians have genetic mutations that allow them to live at high altitudes, and people whose ancestors lived in malarial climes have red blood cell mutations which provide some protection against malaria.
I forgot to mention that this post is partly about the NBA. Aside from the fact that this year's series have often been fabulous competitions, especially those involving finalists Toronto and Golden State, it's pretty hard to miss the fact that NBA basketball is a game mostly played by persons with some African ancestry. This invites the question: is this genetic, cultural, or something else?
A slightly less obvious observation is that the relatively few whites on the court are more likely to be European than from the US.
One crucial point is that NBA players tend to be freakishly tall. The average American male is 5' 10" and the standard deviation is 3". Since the average NBA player is 6' 7", they average three standard deviations taller than the mean - about three in every thousand men are this tall. Six foot eleven guys like Giannis Antetokounmpo and Kevin Duran are in the one in a hundred thousand range. Which wouldn't be anything special in the NBA if they weren't both freakishly athletic and skilled in basketball.
Probably even more important than height is wingspan - the distance from fingertip to fingertip with arms fully extended. The average man has a wingspan about two inches greater than his height, but Giannis has a 7' 3" wingspan and Durant's is 7' 5". Other superstars have exceptional wingspans, 7' for the 6' 8" Lebron James and 7' 3" for the 6' 7" tall Kawhi Leonard.
It's a familiar biological principle that animals nearer the equator, where dissipating heat is a priority, have longer and more slender limbs and bodies, while their high latitude relatives have shorter thicker limbs and bodies, suitable for conserving heat. Humans also seem to fit this pattern. During the first 40,000 years or so of modern humans time in Eurasia, ice ages were often present, adding impetus to heat conservation.
As it happens, long slender limbs, especially forelimbs, are very effective for running, jumping, and several other skills necessary in basketball. Take a look at how slender the lower legs of Giannis and KD are - it's almost shocking. My guess is that if you were designing a perfect basketball player, or at least a perfect small forward, he would look a lot like these two guys. Lebron and Kawhi are more muscular, but they also have relatively slender lower legs compared to their muscular bodies.
So could these sorts of biogeographical evolutionary pressures account for the dominance of persons with African ancestry in basketball and other speed and jumping sports? I would give it a definite maybe. At the same time, one should not discount the role of cultural factors.
Of course blacks have also done well in other sports like gymnastics, where the biomechanical constraints are quite different, if just as specialized. In this regard we need to remember that Africa has more genetic diversity than the rest of the world combined, so it's entirely possible that opposite physical extremes could be lurking in African genomes.
I didn't get to the geeks part, so to be continued.