Think, it's a bred condition. You swim in Africa then you are eaten by Crocs or Hippo's or other predators that are far faster in the water than you could ever be. I'd avoid the swimming in Africa also if I lived there unless the boat capsized then I'd swim my ass off to the closest shore without Crocs visible on or near it and the snakes are so unseen till the fangs penetrate. So I can give them swimming since there were never pools to just take the lesson at for their ancestors. Besides are you going to be the one to accidentally splash water on a black womans hair, fuck no.