Wednesday, May 25, 2005

Why were Tasmanian Aborigines Dark-Skinned?

Scientists, especially those who live in the Northern Hemisphere, often suggest that it is anomalous that the Tasmanian Aborigines were dark-skinned. Here is an example from the prominent Gene Expression blog:


" One point people bring up is the relative darkness of Australian Aboriginals even though much of the continent is in the "temperate" zone. It could be fairness (or the genetic variants that result in it) is not in the "genetic" background of this population, but blondeness among Aboriginals of the deep desert seems to falsify this thesis, and one supposes that the original populations that exited northeast Africa were also rather small and lacking in genetic diversity. But, Australia is mostly dry, and so rather sunny, in comparison to Europe. Only Victoria is really in a temperate maratime climate. And, to my knowledge, no group of Aboriginals wore very much clothing.

A more interesting case is that of Tasmanian Aboriginals. This group, now extinct in an un-admixed state, was very dark skinned, and had been isolated on Tasmania for about 10,000 years. Tasmania does have a cool maratime climate like much of Europe. My impression is that Tasmania aboriginals were not totally naked. "


My comments on this are as follows. Australia straddles the Tropic of Capricorn, so Australia is only partly a temperate zone country. Tasmania itself is at the same latitude in the South as Corsica is in the North. It is not that far South, really. It has a mild climate. Why did the Tasmanian Aborigines have dark skin? Well, one reason, as I've already indicated, is that Tasmania is fairly sunny. It is certainly not Norway, or even Vermont. It is hard to be certain, but some early accounts suggest that the Tasmanian Aborigines did not wear a lot of clothing. Another point is that they were hunter-gatherers, with access to meat and seafood, which could have provided good sources of vitamin D. Oddly enough, there seemed to be a taboo on fish, but they certainly ate seals, seabirds and shellfish. Many of the tribes would have had access to such coastal resources.

In summary, the dark skin of Tasmanian Aborigines is something of a puzzle, but there are some possible explanations that can be fitted into the usual model of human skin colour that relates skin colour to the local levels of sunshine and other sources of vitamin D.


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