&gt; Maybe there is a culture of long distance running in East Africa and West African value short distances over long distances.

The problem with the cultural explanation is that most of the best runners train in the West. Indeed, many of them were born in Western countries like the US or Jamaica to immigrant parents (or are the descendants of former slaves; most slaves were taken from West Africa, because the slave states along the coast there would raid inland and then sell them to white traders in exchange for guns and other goods). If it was a cultural thing, we'd expect white college athletes in the US who train with these people to do just as well. They don't.

&gt; Also there are probably a lot of great West African Distance runners like the San people who don’t participate in competitive running

Very possibly, but we won't know until they actually do.