140triguy wrote:
Which black people have higher bone density? East Africans, who are the best distance runners in the world? Genetically, there is more diversity in all the populations of Africa than there is in the rest of the world combined. There is greater genetic diversity between Kenyans and Ethiopians than there is between Swedes and Italians, for example. Arvidas Sabonis, who played for the USSR and the Portland Trail Blazers, was 7'4". Manute Bol was 3-4" taller: who had the greater "bone density?"
I'm going to say that skeletal density has NOTHING to do with swimming. Just a cursory search found that the skeleton weighs an average of 10% of female body weight and 14% of male body weight. How much would a "denser skeleton" weigh?
Bone structure is a matter of genetics, yes, but inthe real world, there is also the impact of stress loading on bone structure modeling. This modeling doesn't happen uniformly over the body, more just in the area where stress is acting on the bones. For example, my distal humerus, at the elbow where my triceps terminates, has a protuberance from years of swim strokes and the tendons stressing that part of the bone. My rib cage has similar protuberances where my pecs insert into the chest. In runners, you'd expect greater bone modeling in the pelvis and proximal hip (especially the greater trochanter). Conversely, my hips are probably a bit less built up than a runner, and that runner has smaller insertion points in the arms and chest than I do. Even after all that, what is the difference in weight and density?
Even with this greater bone modeling, it doesn't happen uniformly everywhere. It also doesn't significantly raise the weight of the skeleton. In terms of "race," If you assume that there is a greater bone density in a population, you'd first have to examine how significant that density is, which bones are affected, how much the total weight gain would be, and, MOST IMPORTANTLY, how would this affect buoyancy? Very very little.
I agree with everything said above. Does anyone even have a reference for this claim that bone density varies with race? I find it hard to take seriously, especially given that we now understand that what we perceive as "race" does not map in much of a meaningful way to the actual biology of H. sapiens.