The undoubted genetic advantage that athletes of West African descent have in the speed events is without question. But that is a different body type from the East Africans, who are more clearly suited to the distance events. However, their advantage over other racial types may have as much to do with living at altitude than genetic advantage. Thus Caucasian - and a few Asian - athletes have often been able to compete on a par in the distance events, with comparable training. (This is not so in the sprints). What we don't know is how much the bias in favour of any particular racial type has been skewed by the incidence of doping in the countries those athletes have come from or reside in. We do know some countries are poorer at anti-doping control than others.