Seveneves

by Neal Stephenson

Africans carried more genetic diversity within their genomes than non-Africans, as a simple result of the fact that humanity had originated on that continent and spread outward. Non-African races had been founded by isolated groups of adventurers. Breeding among themselves, they had created gene pools that were necessarily limited to what they had brought with them: only a subset of what was to be found in Africa. This idea had been used to explain, for example, why Africa contained both the tallest and the most diminutive people in the world, and why so many top athletes were African. It wasn’t because they were naturally better athletes but because the bell-shaped curve of random genetic variation was wider. For every African who was a great athlete there was presumably another who was miserably uncoordinated, but no one paid any notice to the latter.