these differences across racial lines are not an inhibitor for Black Americans to compete at high levels in sports.
Lord knows how much more staggering the difference could be if all Black Americans actually grew up with good nutrition, education, and training. I mean, the NBA is already 75% African American.
What if it is the case, that all of things you mentioned, and more were provided to lessen the disparity, and yet it still came out as predominately one or two races?
I won't repeat my claims here, but I'll add that at this point, at least part of that overrepresentation is self-perpetuating. Many people expect the next Michael Jordan to look like Michael Jordan. That's why Armon Johnson was almost a first round draft pick in 2010 while Jeremy Lin got passed over completely despite the fact that Jeremy Lin is clearly talented by any objective measure.
I'm also uncertain that: 1) cognitive and physical development have the same inhibitors and 2) those inhibitors affect cognition and physical development to the same extent. I wouldn't be surprised to learn that lead hurts the brain more than the rest of the body.
re: cognitive vs physical development, I think at the level of star athlete most of the difference in performance is, for lack of a better word, mental
If you look at Michael Jordan, Tom Brady, Jeremy Lin, Tiger Woods ... they're very physically gifted, moreso than a typical pro player ... but it's not like they win by being drastically more physically gifted than their competition.
The thing that helps them to win may not be exactly conscious thought, but I think it's effectively a mental/behavioral advantage — certainly to me it seems like a better fit than attributing their success to their physical build (compared to competitors). Michael Phelps on the other hand ... well, some people are just born with the bodies to play certain sports :)
However, sports can differ in what they are in need of when it comes to traits and skills, and like you pointed out, many would negligently exclude that intelligence can also be a factor.
Take American Football - the running back and wide receiver position will ask for almost exclusively physical traits. Players like DK Metcalf fits his position so well almost solely based on his physical performance and players in these positions are predominately Black. However, the Quarterback asks less of the physical and more on decision making, and players in these positions are predominately White.
I believe it to be a mixture of both, although physicality and athleticism takes a lion share of what factors are needed to be successful in sports, whereas intelligence is required in selected sports.
As you mentioned, Michael Phelps has an physical anomaly where he has the legs of someone with a height of 5'10 and the torso of someone who is 6'7, which is what propelled him to become to greatest - but to your point, swimming does not ask much for the mental. Maybe reaction time for starts, and strategies for 400im and anything longer than 400m freestyle, but doesn't ask for much compared to other sports out there.
these differences across racial lines are not an inhibitor for Black Americans to compete at high levels in sports.
Lord knows how much more staggering the difference could be if all Black Americans actually grew up with good nutrition, education, and training. I mean, the NBA is already 75% African American.
What if it is the case, that all of things you mentioned, and more were provided to lessen the disparity, and yet it still came out as predominately one or two races?