Next Saturday afternoon, in less time than it has taken me to type this sentence, the fastest man at the Olympics will take the 100m gold medal. That man may be the pre-Olympic favourite, the American Maurice Greene. It may be Trinidad and Tobago's Ato Boldon. It may even be Britain's Dwain Chambers, who has run in to impressive form in the past few weeks. But whoever it is, of one thing we can be certain: he will be black. The last time a white athlete even appeared in a final, Jimmy Carter was still in the White House. Over the past decade, the ten-second barrier in the 100m has been broken 200 times - but not once by a white athlete. Nor is it just at the 100m that white runners are so noticeably absent. Every men's world record at every commonly run track distance from 100m to the marathon now belongs to a runner of African descent.
Nor is there any respite for white sportsmen away from the Olympics. The American Basketball Association is 80 per cent black; 60 per cent of American footballers are black. France won the football World Cup of 1998 and Euro 2000 with teams in which more than a third of the players were black. In boxing, the two world heavyweight champions - Lennox Lewis and Evander Holyfield - are black.
What lies behind black domination of sport? The traditional liberal answer points the finger at social factors. Black people, so the argument goes, have been driven into sport because racism has excluded them from most areas of employment. Racism also makes blacks hungrier than whites for success. In the postwar world, largely as a consequence of the Holocaust, there has been a great reluctance to see human differences in biological terms. Human beings, we have come to believe, can be explained purely in terms of culture.
Increasingly, this antipathy to biology is wearing away. Biologists, anthropologists and athletes themselves are looking to nature, not nurture, for an explanation of black dominance. "Blacks are made better," argues Carl Lewis, the African American athlete who won four golds at the 1984 Olympics. The American journalist Jon Entine dismisses the environmentalist theory of black athletic prowess as "political correctness". Entine's book, Taboo: why black athletes dominate sports and why we're afraid to talk about it, was published in America this year to great controversy.
The liberal consensus, Entine argues, has served only to disguise the truth about the black domination of sport - which is that black people are built to run and jump. It's an argument that's winning a hearing on this side of the Atlantic, too. On 7 September, the BBC broadcast The Faster Race, produced by its Black Britain team, which argued the case for a natural black athleticism. Channel 4 shortly begins a three-part series, The Difference, which explores genetic differences between races in sport, among other areas. It's time we put away our fears of talking about racial differences, the series argues, and face up to the facts of genetic diversity.
The view that black sportsmen and women have a natural superiority rests on the evidence of physiological research, largely into two groups of athletes: East African long-distance runners and West African sprinters. East Africa, and Kenya in particular, is the powerhouse of middle- and long-distance running. The top 60 times in the 3,000m steeplechase were all set by Kenyan athletes, who also hold more than half the top times at 5,000m and 10,000m. Most remarkably, the majority of top Kenyan runners come from one area in the country - the Kalenjin region, along the western rim of the Great Rift Valley, adjacent to Lake Victoria. Kalenjin athletes have won more than 70 per cent of Kenya's Olympic medals at running events and all but one of all Kenyan-held world records.
A number of lines of research suggest that the secret of such spectacular success lies in superior biology. All muscle contains two kinds of fibres - fast-twitch and slow-twitch. The former is good at producing explosive bursts of energy, the latter at sustaining muscle effort over long periods. Physiologists have shown that the muscles of Kenyan athletes have a higher proportion of slow-twitch fibres than those of white or West African athletes. Kenyans also enjoy a slighter body profile, have relatively long legs and large lung capacities, and possess more energy-producing enzymes in their muscles, which are thus better able to utilise oxygen.
Athletes of West African descent - and that includes most African American, Caribbean and black British athletes - have, on the other hand, a physique that is suited to explosive events, disciplines that require sprinting and jumping. Such athletes possess what biologists call a mesomorphic physique, with bigger, more visible muscles such as a larger chest. Their muscles contain a higher proportion of fast-twitch fibres than those of white people or East Africans. Athletes of West African descent also have less body fat, a higher centre of gravity, narrower hips and higher levels of testosterone in their blood.
For Entine, such physiological and biomechanical differences demonstrate the natural superiority of black athletes. For Entine's critics, on the other hand, the very search for such differences betrays a racist outlook. "I don't think it matters what the biological conclusions are," argues the former footballer Garth Crooks. "It forges a distinction between black and white athletes which is unhealthy, unhelpful and untrue." According to the prestigious scientific journal Nature, "the danger that interracial comparisons will be inhibited by considerations of political correctness is less serious than that interracial studies will be wrongly used".
These critics are responding to a long history of racism in which black athletic superiority has often been seen as evidence of intellectual backwardness. "The Negro excels in the events he does because he is closer to the primitive than the white man," claimed Dean Cromwell, the head coach to the US team at the 1936 Berlin Olympics. "It was not long ago that his ability to sprint and jump was a life-and-death matter to him in the jungle."
Today, too, scientific racists, such as the Canadian psychologist J Philippe Rushton, argue that there is a trade-off between brain and brawn, and that black athletic superiority has been purchased at the price of lower intelligence. In The Faster Race, Rushton argued that Asian and white children are born with bigger heads than black infants. Hence, he said, Asian and white women have a bigger pelvic girdle than do black women. A smaller pelvis, Rushton claimed, is better suited to running. Ergo, Asians and whites are brainier, blacks more athletic.
Such claims may seem deeply offensive, but that is no reason to ignore science or censor data. The debate about differences in sporting ability is part of a wider debate about the meaning of new knowledge regarding genetic diversity. Channel 4's The Difference links racial variation in physical attributes to racial variation in intelligence. The final programme in the series is largely given over to Charles Murray, the co-author of The Bell Curve, to argue that black people are naturally less intelligent that whites and Asians. Liberals who refuse to engage in the debate about natural difference are simply leaving the terrain open to the likes of Rushton, Murray and Entine.
The real problem with the "blacks are born to run" thesis is not that it is politically incorrect, but that it is factually incorrect. The most basic difficulty with it is its confusion of racial and population differences. Different population groups are clearly physically distinct. The Masai of Kenya tend to be taller and longer limbed than the stocky, short-limbed Inuit in the Arctic, because the body forms of both have been shaped by natural selection to suit their particular environments. But that there are physical differences between human groups does not mean that such differences can be reduced to racial distinctions, nor need they necessarily have a consequence in human endeavour, whether that be sport or IQ tests.
It is certainly possible to divide humanity into a number of races, as we conventionally do, according to skin colour and body form. However, it is also possible to do it many other ways - using, for instance, blood group, lactose tolerance, sickle cell, or any other genetic trait. Genetically, each would be as valid a criterion as skin colour. The distribution of one physical or genetic characteristic - say, skin colour - is not necessarily the same as that of another - such as blood group. The current division of the world into black, white, Asian and oriental races is, in other words, as rooted in social convention as in genetics.
Entine rejects such criticisms as mere "semantics", but his own argument shows why it is not so. According to Entine, East Africans are naturally superior at endurance sports, West Africans at sprinting and jumping, and "whites fall somewhere in the middle".
But if East and West Africans are at either end of a genetic spectrum of athletic ability, why consider them to be part of a single race, and one that is distinct from whites? Only because, conventionally, we use skin colour as the criterion of racial difference.
To understand why genetic notions of population difference are at odds with social ideas of race, consider the Australian athlete Cathy Freeman. Freeman, an Aborigine, is the hottest Australian athlete, and a good tip for the 400m Olympic gold. Because of their skin colour, Aborigines are often bracketed with sub-Saharan Africans as a "black" race.
Racial scientists have often argued that Australian Aborigines and black Africans are the two most primitive races in the world. Since Freeman's rise to prominence, there has been much speculation that Aborigines, like black Africans, are natural athletes. Genetically, however, there is no population in the world more distinct from those of sub-Saharan Africa than Australian Aborigines. Freeman is genetically closer to white athletes such as Britain's Katherine Merry than to black athletes such as America's Marion Jones. Here, as in so much else, appearances can be deceptive.
Not only are genetic notions of population differences distinct from political concepts of race, but the physiology of human differences is not easy to interpret in sporting terms. Jon Entine suggests that West Africans have relatively slender calves compared to whites, and that this helps their sprinting ability. It is difficult to see how, because muscle power increases with cross-sectional area; smaller calves should make it harder, not easier, to excel in explosive sprinting events.
Indeed, slender calves are the main biological reason given for the feeble presence of African Americans in ice hockey. Yet the same attribute is seen as enhancing their performance on the track.
It is true that athletes of West African descent living in North America, western Europe and the Caribbean dominate many sports. But contemporary West Africans do not. This is the opposite of what one should expect if athletic ability were predominantly determined by genetics.
In the United States, considerable intermixing between black and white has meant that the African American population embodies, on average, roughly 30 per cent of genes from populations of European descent. Hence, African Americans should be poorer athletes than West Africans. The reverse is true.
What all this suggests is that the relationship between sport, culture and genetics is much more complex than either liberal anti-racists or conservatives such as Entine and Murray will allow. Athletic talent is at least in part inherited, and there are undoubted genetic differences between regional populations. Nor should we dismiss the possibility that West Africans and Kenyans have a genetic advantage when it comes to sprinting or long-distance running.
There is no reason to assume that all populations have physical characteristics equally suited to every athletic activity. But are blacks naturally better athletes than whites? Not necessarily. After all, how many African Pygmies have you ever seen climbing on to the winners' rostrum?
The writer's Man, Beast and Zombie is published by Weidenfeld & Nicolson next month