On Saturday the world will witness the latest chapter in sport's most vivid narrative. The sense of expectancy is notching ever higher as three extraordinary human specimens await their opportunity to do battle for the mythic title: fastest man on the planet.

Usain Bolt, the talented Jamaican, smashed the world record in June but will face muscular competition from Asafa Powell, the former world record-holder, and Tyson Gay, the American who stormed to the World Championships title in Osaka last year. Pundits are sharply divided as to the outcome. The only thing that can be said with certainty is that the winner will be black.

As will all the other finalists. And most of the semi-finalists. Disagree? Then look at the evidence. Black athletes have monopolised every Olympic 100metres for the past quarter of a century, without a white man making the final. The same dominance asserts itself at the World Championships, in which every sprinter in eight of the past nine 100metres finals has been black. The last white athlete to win the Olympic title - Allan Wells, of Britain - did so during a boycott that deprived the Moscow Olympics of the world's top black sprinters.

What conclusion should we draw from all this? That blacks have a genetic advantage over whites when it comes to sprinting? It would seem a natural inference except for a nagging voice giving warning about the consequences. If we were to acknowledge systematic genetic differences between the races, where would it lead us? To the conclusion that the superior performance by whites in education is genetic? These are deep waters indeed. The most famous argument for the reality of black genetic superiority is to be found in Jon Entine's Taboo: Why Black Athletes Dominate Sports and Why We Are Afraid to Talk About It. Entine's principal argument is not that all blacks are gifted at sprinting, but rather those that can trace their ancestry to West African coastal states. Indeed, Entine makes the point that “no white, Asian or East African has broken ten seconds in the 100metres”.

East Africans, by contrast, find their metier in distance running. As John Bale points out in his book, Kenyan Running, athletes from specific regions of the Rift Valley have had amazing success in distances of more than 3,000metres. Up until 1993, the Kalenjin tribe won 317 medals and the neighbouring Gussi people won 78. These figures amounted respectively to 63 per cent and 15 per cent of the 506 medals won by Kenyan athletes in leading competitions.

Entine remorselessly presses home the point that the probability of such a geographically tiny area dominating distance running by mere dint of chance is roughly equivalent to the world self-destructing in the next few minutes. So let us grant that the success of West Africans in sprints and East Africans in distance running has genetic causes. Does that mean that blacks are naturally better athletes than whites?

No it does not. What it means is that West Africans are naturally better at sprinting and East Africans are naturally better at distance running, with whites probably somewhere in between. So why make the further claim that blacks in general are better at sprinting and distance running? The fallacy may not seem obvious, so let us apply Entine's logic to the Central African Bambuti, a tribe more commonly known as pygmies. With an average height of 4ft, we can safely assert that pygmies have a natural advantage at ducking under low ceilings. Does that mean that blacks in general have a natural advantage at ducking under low ceilings? Entine's error lies in his compulsion to generalise.

Finding genetic variation between populations (such as the Rift Valley) is to be expected. Small populations have distinct traits because nature has selected physiques that suit their natural environments. Such genetic differences exist across the planet. But why lump together all the diverse populations that happen to share similar skin pigmentation? Or, to put it another way, why bundle West and East Africans together when, according to Entine's own arguments, they lie on either end of a genetic continuum of athletic abilities?

It is surprising that Entine fails to spot his error when he goes on to discuss the success of the Pacific Islands in producing rugby and American football stars. He seems to think this supports his argument that blacks have a genetic superiority at such sports because they have been “bred to run”. It actually does the reverse: there are few populations more genetically distinct from sub-Saharan Africans than Pacific Islanders.

The one thing Entine is correct about is that the general reluctance to talk about “black” athletic success has bolstered the idea that there is a truth about racial differences that is being suppressed by political correctness. This has done untold damage to blacks in areas in which the stereotype says they are inferior - a suspicion that, in the case of IQ, can be exploded with a few minutes' research.

The conclusion is clear: to invoke race as the explanation for the inevitability of a black man winning on Saturday is not merely unscientific, but also a good 100metres wide of the mark.