on west africans and their (on average) greater amounts of fast-twitch muscles:
“Peering Under the Hood of Africa’s Runners”
“…The differences don’t stop with body shape; there is also evidence of a difference in the types of muscle fibers that predominate. Scientists have divided skeletal muscles into two basic groups depending on their contractile speed: type I, or slow-twitch muscles, and type II, fast-twitch muscles. There are two kinds of the latter: type IIa, intermediate between fast and slow; and type IIb, which are superfast-twitch. Endurance runners tend to have mostly type I fibers, which have denser capillary networks and are packed with more mitochondria. Sprinters, on the other hand, have mostly type II fibers, which hold lots of sugar as well as enzymes that burn fuel in the absence of oxygen. In the 1980s, Claude Bouchard’s team at Quebec’s Laval University took needle biopsies from the thigh muscles of white French Canadian and black West African students. They found that the Africans averaged significantly more fast-twitch muscle fibers — 67.5% — than the French Canadians, who averaged 59%….”
i am totally going with my own personal theory for why west africans have more fast-twitch muscles, and that is because of sexual selection.
for how long have various west african populations been showing off their skillz — like this! — on the dance floor?:
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yup. sexual selection. that’s my theory (with a small “t”), and i’m sticking with it!
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