There is natural talent, which can come from genetics or environmental conditions (like riding bikes to and from work most of the year etc). There is working at improving that talent (training). You can't have one without the other. And given a choice between the two, I am inclined to think most coaches would opt for the latter.

Those people you mentioned in Africa, for the most part, have the "body" i'e. lightness of bones, tall and rangy, or small and compact etc, you get my drift.

I once read a quote along the lines of "Talent alone won't do it b/cos the world is full of derelicts with talent, and that perseverance and hardwork is the ticket".

I once found myself talking to a successful Olympics athlete and coach (he had won a gold medal and coached another successful gold medalist) about the most important characteristic of a champion. He listed about three other qualities b/4 he mentioned talent. The very first quality he mentioned was courage, which he interpreted to mean "the capacity to go way beyond your comfort zone in training, and then adding a little extra in competition.

Just my two cents.