Chris Rock is not an anthropologist, but he plays one on TV. His musings on the human condition are loud, irreverent and laugh-out-loud funny. But if you turn down the volume, excuse the profanity and weed out the humor, you might just discover a morsel or two of truth.

So it is with Rock's bit mocking the dearth of white boxers.

Name a great white fighter, Rock asks a grizzled trainer.

"Alive?" the gentleman responds.

Why can't whites box? Rock wonders later.

"Ever seen 'em dance?" the gentleman says.

In sending up the stereotype that whites inherently lack rhythm, Rock, perhaps unwittingly, treads on a sensitive question with even more sensitive overtones: Are blacks genetically predisposed to success in sports?

Jon Entine, an Emmy-winning television producer, is more direct in his book "Taboo: Why Black Athletes Dominate Sports And Why We're Afraid To Talk About It."

Entine and one of his critics, Wharton School professor Kenneth Shropshire, lectured Thursday at Old Dominion University, and their provocative exchanges, which included a video of Rock's "Great White Hope" bit, transcended sports.

Entine, who first explored this topic in a 1989 NBC documentary narrated by Tom Brokaw, believes blacks' dominance of athletics, especially the core sports of football, basketball and track, is rooted in genetics. He outlined patterned physiological differences that some scientists say explain why athletes of western African heritage excel at sprinting and jumping, while athletes of eastern African heritage excel at endurance events such as the marathon.

"The basis for the success of black runners is in the genes," Bengt Saltin, a physiologist and director of the Copenhagen Muscle Research Institute, says in Entine's book. "There is no question about that."

Shropshire, a Columbia Law School graduate, former NFL agent and author of "In Black and White: Race and Sports in America," does not dispute the science.

"It's just not that important," he told an audience that included ODU President James Koch, basketball coach Jeff Capel and several of Capel's players. "I am not losing any sleep over it."

He is, however, quite concerned that the conversation will degenerate rapidly into the racist "brains vs. brawn" exercise, the notion "that blacks are more animal like and less intelligent." So in Shropshire's mind, Entine does a disservice merely by disseminating the genetic research.

Entine dismissed the blame-the-messenger argument and countered with a quote from Walter Williams, a professor at George Mason: "If decent people don't discuss human biodiversity, we concede the turf to black and white racists."

Neither Entine, who is white, nor Shropshire, who is black, came off as even marginally racist. In fact, they seemed to have more in common than either realized.

Both respect the genetic research. Both cringe at the yahoos who might use the research to promote supremacy causes. Both appreciate the roles opportunity, economics and good, old-fashioned hard work play in forging athletes of every race.

For example, whites dominate golf, tennis and swimming because they have more access to courses, courts and pools. Michael Jordan may have genetic advantages over John Stockton, but neither would have attained greatness without grueling workout regimens.

"Nurture and nature," Entine said, "are inseparable."

Naturally, there are exceptions. Jason Sehorn is the NFL's only white starting cornerback. Brent Barry is the only white to win the NBA's slam-dunk contest. Tiger Woods is the only golfer of African ancestry to win a major championship. Venus and Serena Williams are the first black women since Althea Gibson in the late 1950s to win major singles tennis championships.

But the numbers are overwhelming. More than 70 percent of the players in the NBA, WNBA and NFL are black, and blacks own every world outdoor running record, from 100 meters to 26.2 miles. Complicating the debate: the predominance of whites in the stadiums and boardrooms of sports.

The debate itself speaks to our obsessions with sports and race. But Shropshire is right when he says such obsessions cheat worthier pursuits such as AIDS and cancer research. And Entine is right when he says the obsessions satisfy our natural curiosities and just might teach us a few things about ourselves.

"This is not," Shropshire said, "an easy issue."