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| Yamila Diaz - melanchroi |
Natural selection in Britain during the last 2,000 years
The latest ancient DNA studies from the British Isles (Schiffels et al and Martiniano et al. and Cassidy et al.) support continuity over the last 2,000 years. Sure, there were continued migrations like the arrival of the Anglo-Saxons, but these were very similar groups in the grand scheme of things.
But, while ancestrally the modern Briton is probably a descendant of the Britons of 2,000 years ago with some admixture from similar continental European groups, he is not the same, as (apparently) substantial genetic adaptation has continued to operate in Britain over the same period. A new preprint by Field, Boyle, Telis et al. makes the case for adaptation in a variety of traits in the ancestors of Britons over this period. Mind you, the genetic underpinnings of many important human traits known to have high heritability are currently unknown, but there is little doubt that selection would have affected traits beyond those detected in this study. I am quite curious to see whether the striking efflorescence of cultural achievement in Britain over the last half millennium could have (at least in part) a genetic underpinning.
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| Candace Swanepool - Xanthochroi |
Depigmentation is a trait whose genetic architecture is as well as understood as any. The results of this study might surprise writers of decades and centuries past who supposed that the spectrum of pigmentation of modern Europeans was the result of admixture-in varying measure- between Xanthochrooi and Melanchrooi races of primordial antiquity. All indications seem to be that depigmentation of hair, skin, and eyes did not co-occur in such a hypothetical race, but rather in different parts of the Caucasoid range, only reaching a high combined frequency in northern Europe to form the distinctive physical type that is distinctive of the natives of that region. It would be quite interesting to see how these traits evolved in Fennoscandia and the Baltic, regions that sport an even higher depigmentation than the British Isles. Traditionally, these areas were viewed as refuges of the Xanthochrooi but it may very well turn out to be that for whatever reason selection has acted in that area as well, as it did in the Eastern European plain where rather dark Bronze Age steppe groups gave way to rather light pigmented living eastern Slavs.
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| Kelli McCarty - mixed |
OK, I sort of got what he meant from the context, but let's consult the wiktionary just to make sure:
It's interesting that the three distinctive features of the "Nordic" type, blond(e) hair, fair skin, and blue eyes appear to have originated (or at least originally proliferated) in different parts of the European peoples, but found a center in the north in which selection pressure for all three traits was so strong as to become predominant in the people of that region.
We think we know why light skin is favored in cold, dark regions and dark skin in tropical areas. Sunlight destroys folic acid in the skin, while it makes vitamin D. In areas where maximum clothing is necessary, and sunlight is minimum, fair skin allows production of adequate vitamin D with minimal skin exposure. In the tropics, minimal clothing is necessary for heat, but dark skin protects from folic acid degradation.
We're much less sure about the proliferation of fair hair and blue eyes. Human men, or maybe just American men appear to have developed a taste for women with both, so "sexual selection" is one hypothesis. Sexual selection is the force that has some male bird wearing fancy feathers and bright colors that make them more susceptible to predators, but that are favored by the females of the species.
Late Night With Rule 5 Monday done come on Tuesday (our time) at The Other McCain, thanks to Wombat-sochos participation as a delegate to the Nevada State GOP convention in Reno.
Xanthochroi: A division of the human population having fair skin and wavy blond hair.I'm not quite sure what the slight difference in spelling means, but maybe plural? Anyway, I think you can figure out melanochroi from there.
It's interesting that the three distinctive features of the "Nordic" type, blond(e) hair, fair skin, and blue eyes appear to have originated (or at least originally proliferated) in different parts of the European peoples, but found a center in the north in which selection pressure for all three traits was so strong as to become predominant in the people of that region.
We think we know why light skin is favored in cold, dark regions and dark skin in tropical areas. Sunlight destroys folic acid in the skin, while it makes vitamin D. In areas where maximum clothing is necessary, and sunlight is minimum, fair skin allows production of adequate vitamin D with minimal skin exposure. In the tropics, minimal clothing is necessary for heat, but dark skin protects from folic acid degradation.
We're much less sure about the proliferation of fair hair and blue eyes. Human men, or maybe just American men appear to have developed a taste for women with both, so "sexual selection" is one hypothesis. Sexual selection is the force that has some male bird wearing fancy feathers and bright colors that make them more susceptible to predators, but that are favored by the females of the species.
Late Night With Rule 5 Monday done come on Tuesday (our time) at The Other McCain, thanks to Wombat-sochos participation as a delegate to the Nevada State GOP convention in Reno.
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