And East Africans have the best bodies for endurance running. Asians, on the other hand, happen to have more flexible body types, so they excel at gymnastics, ice skating and diving. In evolutionary terms, West Africans were also more insulated than other people on the continent and other populations throughout the world, and so have a more common gene pool. Environment and culture, in fact, becomes embedded in the genes. You cannot bifurcate culture and genetics.
All genetic changes are the result of environmental adaptations.
All the scientific and anecdotal evidence are in accord. I was trying to ensure that I was clearly and calmly conveying the science, and putting it into political and social context. What has heartened me is that the African-American response has been remarkably positive. For hundreds of years, blacks have been subjected by some to the racist belief that they are more animalistic and, so, less intelligent. But that's ridiculous.