"However, I am allergic to people making claims that are based on formulations like...well, isn't it possible that X could have happened."
I'm not making any claims.
I'm saying this
http://realhistoryww.com/world_history/ancient/Misc/Common/India/Indian_Albinos/The_Bhatti.jpg
and this
http://en.wikipedia.org/wiki/Xirong#Ethnicity
"The 7th century commentary to the Hanshu by Yan Shigu says: "Among the various Rong tribes in the Western Regions, the Wusun's shape was the strangest; and the present barbarians who have green eyes and red hair, and are like a macaque, belonged to the same race as the Wusun."
may be related.
Other people are saying they *can't* be related because of the SLC genes - which makes no sense.
Maybe they're not related. Maybe the Wusun, Libyans, Thracians, Hyperboreans got the skin color from the SLC genes and the red hair, green eyes from MC1R although that begs the question why should the MC1R gene have been more widespread in the past than now?
Either way there's a piece of the puzzle missing.
I haven't recently looked at the genes which cause albinism, but it's my recollection that the MCIR gene is not one of them. You might want to look that up.
The fact that there are so many descriptions of red haired people in ancient literature and a relative paucity of this phenotype in modern Europeans is something that I do consider interesting. I wonder if part of it is caused by less than subtle translations of ancient languages. For example, the Ligures, from whom I am at least partly descended, were described as red-haired. However, I'm not sure whether that is the way that the Latin should be translated. I'm basing that on the fact that in Italian, brown haired people are often described as having chestnut colored hair. An actual chestnut is a reddish brown, and brown hair which has been exposed to intense sun has a definite reddish hue. Mine certainly does. Perhaps the ancient authors meant that the people they encountered had reddish brown hair. By October, a great many people in Liguria could be so described. (If anyone has a link to the actual Latin I would appreciate it, so I can see for myself which exact word was used. I haven't been able to find it.)
Assuming for the moment, however, that the ancient authors, at least in the case of the Ligures, meant actual red or red gold hair, it is certainly not common in Liguria today. You do find it, however, in the Apennines of Emilia, which were also Ligure territory. I happen to know because my father's family comes from there, and half of them have red hair, ranging from red-gold, to awful carrot orange, to auburn. They also are heavily freckled, particularly in childhood. My tentative speculation is that it's the result of a founder effect and then drift in very isolated populations where phenotypes based on recessive alleles can survive.
I don't think the fact that this phenotype is most common today in the areas of Europe most isolated from population flows is an accident (also the cloudiest, of course). There's also the case of the Ashkenazim, a 'very' bottlenecked population, where this phenotype has persisted in rather surprising numbers.
I think other factors 'might' also be involved with the diminution in numbers. The kind of skin which is frequently although not always found in red-haired people is extremely prone to sunburn, and the resulting dangers, in primitive societies, from infection. (Anyone with this kind of skin can attest to the absolute mess you can get in if you blister badly and then the blisters break.) In a climate with a strong sun, that's hardly an optimal adaptation, and I wonder if it might have impacted survival. People who carry it are also very prone to melanoma, although that appears later in life and so people would presumably already have had a chance to reproduce. Then there's the fact that at least in Italy, and I think more widely in Europe, red-haired women, in particular, were considered head strong, temperamental, and altogether not very good marriage material. In some places, it was even considered an indication of an association with the "dark" arts and they were actively persecuted. Perhaps all of these factors have caused the decrease in numbers.
As for albinos, it is absolutely 'not' an adaptive trait. They often have other physical ailments in addition to terrible vision problems. I can't think of a more maladaptive trait in a hunger-gatherer society than bad vision.
Also, I don't want to leave the impression that I think everything is crystal clear in terms of the occurrence and spread of the mutations causing de-pigmentation, because I don't. While the scientists have made a good start, there's a long way to go in understanding this and many other aspects of our genomes.
