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?:
yup. sexual selection. that’s my theory (with a small “t”), and i’m sticking with it!
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…they can work that out from your mtdna. with a fr*ckin’ 80-90% accuracy rate! awesome. (don’t ask me what a ‘support vector machine’ is, but it sounds awesome, too!)
it’s “coarse ethnicity” — for instance caucasian, asian, african, hispanic — but still:
Inferring ethnicity from mitochondrial DNA sequence
“Background: The assignment of DNA samples to coarse population groups can be a useful but difficult task. One such example is the inference of coarse ethnic groupings for forensic applications. Ethnicity plays an important role in forensic investigation and can be inferred with the help of genetic markers. Being maternally inherited, of high copy number, and robust persistence in degraded samples, mitochondrial DNA may be useful for inferring coarse ethnicity. In this study, we compare the performance of methods for inferring ethnicity from the sequence of the hypervariable region of the mitochondrial genome.
“Results: We present the results of comprehensive experiments conducted on datasets extracted from the mtDNA population database, showing that ethnicity inference based on support vector machines (SVM) achieves an overall accuracy of 80-90%, consistently outperforming nearest neighbor and discriminant analysis methods previously proposed in the literature. We also evaluate methods of handling missing data and characterize the most informative segments of the hypervariable region of the mitochondrial genome.
“Conclusions: Support vector machines can be used to infer coarse ethnicity from a small region of mitochondrial DNA sequence with surprisingly high accuracy. In the presence of missing data, utilizing only the regions common to the training sequences and a test sequence proves to be the best strategy. Given these results, SVM algorithms are likely to also be useful in other DNA sequence classification applications.”
(but don’t forget — race doesn’t exist. it’s juuuust a social construct….)
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