Well, mg, much of your comment, while containing some truth, is oversimplification and not really addressing Watson's argument nor some of the more serious responses to it.

Myopia (at least the optical if not the cultural version) has some genetic input and may have negative selection pressure applied to it but it still recurs in the human population, probably because as a human population our culture is not quite as red in tooth and claw as the more biassed social Darwinists might portray society.

Watson's proposition about "equal powers of reason" was an implied attempt at categorising the whole of the population with black skins by comparison with the whole of the population with white skins. At such a gross level it is patently nonsense, even though some cultures "may" have more of a reason to cultivate some types of thinking in preference to others. We can all delight in east African long distance runners having a genetic predisposition favouring such activities, putting us mere mortals at a disadvantage for medals in marathons but it is only a predisposition. Not all people with the whole of their ancestry in east Africa have such genetics and I've yet to see any evidence that properly and precisely supports the proposition that selection pressure has had any effect on any population's (let alone an individual's) "powers of reason".

With his achievements great as they are, you'd expect Watson to raise his public heuristics above the level of a middle high school debating topic.

Cheers, Rowan