posted
Tasmania has a temperate climate and is pretty high latitude (approx. 40 degrees from the equator), so why are the native peoples of Tasmania, who have lived on the island for 40,000 years, black-skinned? Why haven't they all died from lack of vitamin D?
Posts: 7069 | From: Fallbrook, CA | Registered: Mar 2004
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posted
It doesn't have to do with heat, firstly; otherwise Ethiopians would be white. Although they are at a latitude with lower UV levels than most of Africa, this doesn't mean that they should today be light-skinned. You can't just take into account what's beneficial but also what genes are present, since natural selection is a blind trend towards better suited forms for an environment, not a conscious adaptation to environments. Simply put, the mutations that caused lighter skin in East Asians (a separate mutation caused it in Europeans) had not yet occurred when the island was settled, and there wasn't any introduction of the gene from East Asia (or Europe) to the island after the mutation occurred. Therefore, the mutation could not be selected for as it was never present on the island. If the mutation had reoccurred or another mutation with similar effects had occurred, then it's possible that its inhabitants would have been lighter-skinned.
-------------------- "Oh the sons of Ethiopia; observe with care; the country called Ethiopia is, first, your mother; second, your throne; third, your wife; fourth, your child; fifth, your grave." - Ras Alula Aba Nega. Posts: 1024 | Registered: Jun 2006
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It doesn't have to do with heat, firstly; otherwise Ethiopians would be white.
It may be necessary to note why you say this, as it might not be immediately apparent to anyone who isn't familiar with the topography in that country...because many parts of Ethiopia lie on mountains.
Posts: 1947 | Registered: Sep 2005
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posted
^ This issue was addressed before and was addressed again in the North African climate thread.
Skin color has NOTHING to do with temperature and everything to do with UV rays of the sun. Tazmania lies only a little outside the tropics, so is therefore subtropical. Also, the Khoisan who are relatively light-skinned have been living in the subtropics (Southern Africa) for far longer than 40,000 years and so have adapted. There are other factors involved such a diet. The Inuit (Eskimos) are relatively dark-skinned for a people living in the arctic with little UV rays, because of their diet of fish and sea mammal blubber which is rich in vitamin D. Perhaps the Tasmanian diet was similar.
By the way, the Tasmanian people became extinct thanks to European colonists.
[ 24. June 2007, 08:37 PM: Message edited by: Horus_Den_1 ]
Posts: 26243 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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posted
Djehuti, the artic has damaging sun rays. You need a lot of sunblock and good sunglasses when you are in an open cold sunny area. Some cold places stays dark or stays darker longer than others while other cold places stays sunny with damaging sun rays longer than others.
Posts: 2088 | Registered: Feb 2007
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^ I don't have a clue as to what you are talking about. UV rays are only damaging if they are in high amounts and especially if the skin has low quantities of melanin.
Posts: 26243 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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