The conventionally acceptable view of blacks in sports would stress culture and environment. Blacks have risen to such paramountcy in so many sports because they are denied access to opportunities in other areas of life, this argument goes, or because the sports heroes who have already made it are compelling role models. Entine says, by contrast, that environment is only one factor. His view is that men and women from Africa or of African ancestry possess genetic attributes that make them superior in certain sports.

"The decisive variable is in our genes," he writes. "There is extensive and persuasive research that elite black athletes have a phenotypic advantage -- a distinctive skeletal system and musculature, metabolic structures and other characteristics forged over tens of thousands of years of evolution."

Entine makes a careful and reasoned case for this point of view, and he argues forcefully against whatever tendency there may be out there in the world of racial politics to misinterpret it. This does not mean that he sweeps away all contrary arguments once and for all. Indeed, reading "Taboo: Why Black Athletes Dominate Sports and Why We're Afraid to Talk About It," I was not convinced that environmental and cultural explanations are inadequate to account for the phenomenon under discussion. Other instances in which a population dominates an area of activity -- Jews (and increasingly Asians) on stringed instruments, Russians in chess, Cubans in Olympic boxing -- are clearly not explained by evolutionary divergence, and the utter domination by blacks of basketball and track might not be either.

Still, Entine thoroughly covers the ground. He begins with an overview of the current sports situation to show the extent of black supremacy, citing, for example, the remarkable fact that "every world record at every commonly run track distance now belongs to a runner of African descent." Even in more racially mixed sports like baseball, Entine produces studies showing that blacks are, on average, better than whites by an important statistical margin.

Along the way he includes accounts of major episodes in the morally and politically rich American history of blacks in professional sports, including the troubled career of Jack Johnson, the first black heavyweight boxing champion; the triumphs of Jessie Owen and Joe Lewis; and the explosion of black power at the 1968 Olympics.

But the heart of Entine's study is an examination of the debates that rage in the fields of genetics and evolutionary biology. Here he does not accept the idea that race is merely a subjective quality, a social construct corresponding to no physical reality. In several chapters he advances the theory that while all humans have a common ancestor, there are several racial lineages within that family, lineages that have some different and even measurable characteristics, described in detail in this book.

This is, as Entine suggests in his title, not a politically easy subject, and he makes every effort to distinguish himself from the long European history of crude race theorizing. He is fully aware of the nasty double bind that blacks, especially in the United States, have always been in when the subject was sports. During the long years when sports were mostly segregated, the common assumption was that blacks didn't have the reflexes or the character to be as good as whites.

Entine in this regard cites the immortally ill-advised words of the sports columnist Jimmy Powers who, commenting in 1945 on the news that Jackie Robinson had been hired to play for a Brooklyn Dodgers farm team, wrote, "The Negro players simply don't have the brains or the skill."

Once black athletes had made cinders of that notion, a different but also racist assumption took its place, namely that the natural athleticism of blacks was a corollary to other supposed attributes: a more primitive nature, greater brutishness, less intelligence. The problem is that once you have isolated one genetic distinction in a racial population, even an advantageous one, the field is open to find other racial attributes, including disadvantageous ones. For this reason many people both black and white have not only felt uncomfortable with arguments about genetically based athletic prowess, some have denounced as racist those who have expressed opinions about that prowess.

"Although people accept the role of genetics in individual differences -- not many of us would expect to survive a one-on-one game of hoops with Allen Iverson -- any evidence that innate differences exist between races or the sexes is considered inflammatory and inadmissible by the prevailing intellectual zeitgeist," Entine writes. He then repudiates the common equation of "natural athleticism" with intellectual inferiority.

"It cannot be stated too strongly that the data that conclusively links our ancestry to athletic skills have little or anything to say about intelligence," he writes. "Differences on the track or basketball court do not necessarily mean differences between the ears."

Overall, the argument can be summed up in a quotation that Entine provides from Joe Morgan, the black Hall of Fame baseball player, now a broadcaster: "Blacks, for physiological reasons, have better speed, quickness and ability. Baseball, football and basketball put a premium on these skills." Entine, illustrating this point, cites the experience of a Swedish researcher who brought a half-dozen top Swedish runners to Kenya, where they were soundly trounced by East African schoolboys at every distance. The Swede concluded that there were 500 boys from that one small area in Africa who could beat the best his country had to offer.

The possibility remains, nonetheless, that culture has more power than Entine realizes, that such things as habitat, childhood experience, local custom and the unavailability of alternative avenues to fame and fortune (Swedes, let's face it, have more nonsports chances than Kenyans) can be decisive. Still, Entine's conclusion that racially distinctive features are an essential element of the picture is part of a sophisticated argument that, whether entirely persuasive or not, cannot be dismissed.