Even if we accept that the lack of black swimmers is down to social factors raised in that article, it is still clear the black people dominate many events where there are no barriers to white people such as sprinting. I find it hard not to put it down to black people just being superior genetically.
And Black people are very successful in the long distance events, obviously not the caribbean nations/north America, what is this attributable too, whereas European nations very rarely if at all win in these marathon events.