Evolution of fair skin color

[Irbis]

I got yet another questions, directed mostly at people knowledgeable about evolution ( CharonY, Arete, chadn737 etc.)

 

How did fair skin color evolve and got fixed in the population? The trait is dominant pretty much only in two regions of the world - Europe and East Asia.

 

One dude whom I know from another (Polish) discussion forum says that the prevelance of fair skin and blonde hair in Europe is due to sexual selection - it is easier to spot various skin imperfections and aging signs on a lighter skin than it is on a darker one + blonde hair are (I don't know what he based his opinion at) thinner and more pleasant to touch.

 

He wrote an entire lenghly essay (which was to be a refutation of racists) but unfortunately it's written in Polish and I doubt anyone here is capable of reading Polish. I will try to translate it soon

 

However, what is certain is that other populations living in similar climatic conditions did not evolve these traits. Aboriginal Tasmanians have been living in isolation in an Europe-like climate for more than 10000 years, yet they were as dark as the darkest African populations. Given the fact that there are albinos born every generation in all parts of the world (including India and Africa) I doubt that not a single allelic variant for light skin/hair arise during these thousands of years in Tasmania.

Edited July 17, 2014 by Irbis

[chadn737]

Light skin is not the same as albinism. Albinism is typically a single gene trait resulting from a mutation in tyrosinase. In contrast, white skin color is a complex quantitative trait controlled by numerous genes.

 

Secondly, blond hair color is not related to skin color. Blond hair is actually quite common in some Aboriginal populations of Australia, the Solomon Islands, and this region of the world.

 

The most prevailing theory is that white skin is an adaptation to more Northern climates, allowing for increased Vitamin D production in the body. While lacking in Inuit populations, the Inuit diet also consists primarily of fish, and so is already rich in Vitamin D. There is not really any evidence that white skin is itself due to sexual selection, although this has been suggested in the case of blond hair.

[Ten oz]

Aboriginal people are believed to be the oldest living isolated population on earth. They left Africa and traveled through Asia 20,000 years before Asia was populated. There migration out of Africa was a seperate one they have remained isolated.

http://www.australiangeographic.com.au/news/2011/09/dna-confirms-aboriginal-culture-one-of-earths-oldest/

 

Race is skin deep. All humans have shared DNA and go back far enough and we are all related. The prevalence of one trait vs another has a lot to do with who killed whom, who raped whom, and who thought whom was attractive.

http://web.mit.edu/racescience/in_media/what_dna_says_about_human/

[overtone]

 

 

However, what is certain is that other populations living in similar climatic conditions did not evolve these traits. Aboriginal Tasmanians have been living in isolation in an Europe-like climate for more than 10000 years, yet they were as dark as the darkest African populations.

 

Tasmania is an island (the majority of its aboriginal human habitat is coastal, with an ocean moderated climate) north of the 45 degree line (its sunlight regime similar to that of Spain or Italy).

 

Humans can live in Tasmania with minimal or no clothing in sunlilght equivalent to the beaches of a Mediterranean island, and maintain access to seafood fairly easily.

 

It does not impose the severity of Vitamin D selection pressure the inland regions of continental Eurasia impose - with dependence on complete bodily clothing, months of very low sunlight, and little if any access to seafood.

 

In addition, we have some indication that the social regimes of midcontinental Eurasia at the transitional time might have been unusual: the degree of dependence on hazardous and long range big game hunting that seems to have characterized human life there for thousands of years is possibly unique among human evolutionary pressures. It's possible that there was a sexual selection regime in which a relatively small number of surviving and successful expedition hunting men routinely chose from a competing oversupply of economically borderline and unusually dependent women. (That sounds kind of normal these days, but in pre-agricultural human populations all over the planet women have usually been the major providers of food and the like, and they have held significant counterbalancing power of sexual choice from an oversupply of competing men accordingly.) That situation, if it existed as seems indicated, would put a small but possibly significant extra value on striking features such as eye and hair color in the very situation in which alterations of melanin-production genetics were otherwise finding most advantage - the region inland from the Baltic Sea. http://en.wikipedia.org/wiki/Eye_color

Edited July 17, 2014 by overtone