Thanks for the question Ken. This is a sensitive and controversial topic. Author Jon Entine, in his book Taboo: Why Black Athletes Dominate Sports and Why We're Afraid to Talk About It (PublicAffairs, 2001), writes that, "anyone who attempts to breach this taboo to study or even discuss what might be behind the growing performance gap between black and white athletes must be prepared to run a gauntlet of public scorn, survival not guaranteed."
Even so, the proof would seem to be overwhelmingly in the affirmative. This article from 2002, discussing the positive impact of black athletes in the sport of bobsledding states that "athletes of West African ancestry... hold 494 of the 500 top, all-time, 100-meter times." A quick look at the top list on Peter Larsson's fabulous statistics database shows that this fact still holds true in 2007.
Jon Entine states in this article that "every men's world record at every commonly-run track distance belongs to a runner of African descent." Take a look at the chart (in the section titled The Rise of the African Athlete) to see for yourself. All but a handful of world records are held by athletes of West or East African descent. (Note: the article was written in the late 1990s. Six of the records on the chart have since been broken, 4 by East Africans, 1 by a West African, and 1 by an Chinese Asian.) Proof like that, again, would seem to be incontrovertible.
Not everyone agrees, including sociologist Harry Edwards of University of California/Berkeley:
"What really is being said in a kind of underhanded way... is that blacks are closer to beasts and animals in terms of their genetic and physical and anatomical make up than they are to the rest of humanity. And that's where the indignity comes in."
Indignity, or incontrovertible proof? I've presented both sides. I'll leave it to you to make your own decision. If you want to dig a little deeper into this subject, including taking a look into the science, here's a good place to start.