(FORTUNE Magazine) – With the summer swimming season now hard upon us, it is time to testify on the issue of racial differences in buoyancy -- the ability of would-be natators to stay afloat without water wings. As you are already intuiting, we got interested in this previously nonburning issue as a result of the famous remarks of Al Campanis on the Ted Koppel Nightline program last April 6. In the course of trying to explain why there had been few black managers in baseball, Campanis -- then an official of the Los Angeles Dodgers and now retired -- made a number of rambling remarks about black-white differences and at one point came out with: ''Why are black men, or black people, not good swimmers? Because they don't have the buoyancy.'' Our initial surmise about those words was that Campanis might well be right. It is uncontested that people with some kinds of muscular physiques have trouble staying afloat, and it seemed plausible that the black race might be over-represented among the ''sinkers'' (as swimming coaches call them). In any case, we had some trouble viewing the issue as controversial. Why is it prejudicial to suggest that blacks are below-average in buoyancy? After all, whites are below-average in basketball. So we were startled to see the buoyancy theory branded ''racial claptrap'' in the Washington Post and ''unfortunate'' in the more restrained New York Times editorial. With the recent appointment of Harry Edwards as an affirmative-action arm-twister for major league baseball, we've been reading more editorial replays of Campanis's remarks, and more op-ed fire-breathing about buoyancy. The party line is that any suggestion of differences among races betokens rampant bigotry. Having now looked into the issue, we depose that contrary to everything you have been reading, Campanis was right about buoyancy. The science of physiology tells us that buoyancy is affected by body density (weight in relation to mass) and body fat. Body fat helps you float because it weighs less than water (about 0.9 grams per centimeter squared, vs. 1.0 grams for water), while bones, muscles, organs, etc., weigh more (averaging perhaps 1.1 grams.) Numerous studies have shown that black bone density is higher than that for whites -- about 5% to 10% higher. It also seems likely, although here the data are less clear-cut, that young athletic blacks have lower body-fat levels than young athletic whites. Says Professor Richard Mazess, professor emeritus of medical physics, at the University of Wisconsin: ''Basically, blacks have heavier bones and lower body fat. That combination makes for an overall higher density.'' Needless to say, these data are for broad population averages, and there is plenty of overlapping among the races. So many blacks are good swimmers. And many whites are still making it in the NBA.