So, is slavery responsible for the athletic performance of African Americans?

[Retrograde]

67. At world-class levels we see people who have been selected to be especially good in their sports

People of any background who love to run but have shorter limbs will, given the same opportunities and levels of training, generally not do as well as people with longer limbs, especially in the sprints. For the same reason, pro basketball players tend to be tall. In longer races, where endurance takes the edge over sheer speed, the favored body types are different.

Since athletics is an area where Black American athletes have excelled, there's probably a lot more encouragement for talented Black youngsters to go into track and field - it also doesn't require as much financial outlay as a lot of sports. So, I think it's a combination of good genes with development of native talent.

If I were breeding people for field work, I'd go for stamina and endurance rather than quick starts.