Anthropology.net calls my attention today to this paper:
Eimear E. Kenny et al., Melanesian Blond Hair Is Caused by an Amino Acid Change in TYRP1. Science 2012. Pay per view.
Naturally blond hair is rare in humans and found almost exclusively in Europe and Oceania. Here, we identify an arginine-to-cysteine change at a highly conserved residue in tyrosinase-related protein 1 (TYRP1) as a major determinant of blond hair in Solomon Islanders. This missense mutation is predicted to affect catalytic activity of TYRP1 and causes blond hair through a recessive mode of inheritance. The mutation is at a frequency of 26% in the Solomon Islands, is absent outside of Oceania, represents a strong common genetic effect on a complex human phenotype, and highlights the importance of examining genetic associations worldwide.
Actually natural blond hair is also found in West and Central Asia and North Africa, and red hair even in the Horn of Africa now and then. But I guess that's what the authors mean by "Europe", duh! It's also found occasionally among South Asians, specially the young, and among SE Asians regardless of age.
Whatever the case with the authors ethno-geographic misconceptions, the results are still most interesting: the gene causing blond hair among Melanesians (and some relatives like Fijians) is not the same as those involved in blond hair in Europe. Mind you that it is not clear yet which are these European genes of blondism but it is clear that the Melanesian allele is not it either.
There is also an article at New Scientist.
"the gene causing blond hair among Melanesians (and some relatives like Fijians) is not the same as those involved in blond hair in Europe".ReplyDelete
Haven't I been trying to tell you that all along?
"Actually natural blond hair is also found in West and Central Asia and North Africa, and red hair even in the Horn of Africa now and then".
Now, that could be the same as European blondism, and the product of movement into Africa.
"It's also found occasionally among South Asians, specially the young"
As is the case in Australian Aborigines. Probably a different gene yet again.
By the way, my mother has always said that a family of Maoris she went to school with had red hair, but they had no known European ancestry. Presumably that was the same recessive gene covered in this post.
Nice work by the authors. Of course, we would all have been gobsmacked if the result has been different. Surely there must be dozens of possible mutations which could result in light coloured hair. The odds of the same one happening on opposite sides of the planet had to be very low.ReplyDelete
We did not know. I suspected indeed that there could be a single shared mutation with random founder effects here and there. Something related to mtDNA N for example. It's not like Australasians and Europeans are that remotely distant, only somewhat.Delete
Weren't there already a study saying that several years ago? I'm pretty sure I've read it a long time ago.ReplyDelete
AFAIK not: the matter was open. I have more than once speculated that blond hair or variants of it could have a single origin at the OoA/Great Eurasian expansion and nobody has ever thrown any such study to my face, which would have been quite relevant.Delete
One of the study authors estimates that "5-10%" of the island's children have noticeably blondish hair. (This is from glancing at a large group of kids playing on the beach). If anything like Europe, this darkens with age.ReplyDelete
What share of adult Melanesians have blond hair?
For that matter, what share of Europeans with blond hair as children have non-blond hair by adulthood?
IMO (and particularly for SW Europe) hair darkens with age (and/or falls down, goes white) but does not become black. Blond people as children can be ash-blond or vaguely brownish as they age but their hairs do not go black. Eventually they go grey instead and get dyed and it becomes impossible to evaluate.Delete
However my mother swears that I was born blond and my hair darkened within days. So there may well be exceptions to that general rule. But still if I leave my hair long it goes dark brown, not true deep black as my cousins', a difference that is very difficult to measure without the appropriate contrast and light (I was not aware of it until a few years ago, when a Portuguese argued that true black hair was very rare in Iberia, that what we call "black" is actually very dark brown - he seems to be right).
Yeah, there are a ton of differences not resolved, to date.Delete
My hair was quite fair and bright blond until about 5, then turning straw blond and dirty blond to age 11, from then first turning dark blond to later brown at age 20 or so, but always receptive to getting more blondish due to UV and sea water (= mild natural peroxide) exposure.
Today, much of my hair is white, especially at the fringe and bottom, where otherwise it is very dark brown to almost black. At the top, it is still naturally dark blond or light brown. It is interesting to have 4-5 natural colors in ones hair.
Curious indeed but it's all gradations of eumelanin after all. I mean that in a sense it should not surprise us: the body (the hair in this case) produces eumelanin and does so in different amounts depending on genetics, age and maybe other factors. It explains all the range of colors you have described: from white (zero eumelanin) to dark brown/black (plenty eumelanin) going through various intermediate shades of yellow/brown (intermediate amounts of eumelanin).Delete
If pehomelanin would be involved, reddish colors would appear, specially with the lighter shades.
And that's all the biological "mystery" of human pigmentation. Another issue is what genes and pseudogenes (epigenetically modified genes) control it.
"I was born blond and my hair darkened within days".ReplyDelete
Mine stayed b;ond until I was about 12. It is not very dark now though.
"IMO (and particularly for SW Europe) hair darkens with age (and/or falls down, goes white) but does not become black".
In Australian Aborigines it becoames black.
Making claims with no base again.Delete
Maju, you idiot. I lived in Australia for four years, and have visited several more times. I've spent a fair amount of time with Aborigines in various regions within Australia.ReplyDelete
The "super-expert" forgets the many pics of adult Australian Aborigines with blond, brown or red hair we have discussed previously.Delete
And I either said at the time (or couldn't be bothered saying) that the girl especially did not look like a 'pure' Aborigine. She probably had some European ancestry, as many Aborigines do. The other blond ones were very young.ReplyDelete
I don't think so. Find us a photograph of a blond-haired Aboriginal adult male. The only 'blond' Australian Aboriginee I've ever seen are children. There are a few photographs of blondish Aboriginal women on the Net, but they all look to have bleached their hair in some way or another. They are not naturally 'adult blond'.
http://jasonchu.com/images/samsonposter.jpg (same couple)
http://rockladyremembers.blogspot.com/ (several pics on the right side of one or two blond-haired adults)
Whatever the case I see brown-haired and white-haired but not really so many black-haired AAs, which was your claim.
Also it is false that many aborigines have some European ancestry. As with the "Captain Cook" gene among Melanesians and Fijians, it is a total misconception: mixed AAs look vaguely Mediterranean or like George Clooney more or less, they are easily spotted as such mixed people.Delete
"Whatever the case I see brown-haired and white-haired"ReplyDelete
The first two links are the subjects of a book cover and I have no idea what region they are from. I agree that the male looks fairly 'pure' Aborigine however. As to the last link the two women with 'blond' hair were exactly the sort I was thinking of when I mentioned bleaching. If you look at the photographs you will notice that the roots of the hair are basically black. That is the natural hair colour of the individual.
'Also it is false that many aborigines have some European ancestry".
That commnet is complete rubbish. i know several Aborigines who claim to have some 'white' ancestry and many 'white' Australians who claim to have Aboriginal ancestry.
"mixed AAs look vaguely Mediterranean or like George Clooney more or less, they are easily spotted as such mixed people".
Rubbish again. That may hold for the 'first cross', but most have several generations of back-crossing with one group or the other.
Not "black" but "dark" (ash or brown).Delete
Could this be a genetic contribution of the Denisovans?ReplyDelete
Not likely because it'd be in the news all around (the Denisovan genome is very well preserved so direct comparison is possible). This issue of pigmentation is still ill-understood via genetics and hair is the less understood of all (not just pigmentation, also texture).Delete
A lot of things have re-evolved, for example we know that some Neanderthals had red hair but that their "red hair allele" is not found in modern humans (also modern "red hair alleles" are found in Africa, although darker pigmentations hide their effects). Red hair alleles do not just affect hair but also skin and in one common case effect of some anaesthesics (lower, they need extra doses).
What we do know is that some Neanderthal alleles have been selected for in non-Africans, notably one for keratin (which should affect skin, nails and hair). My pet hypothesis here is that straight hair, which is clearly not ancestral in H. sapiens (Afro-curly is) quite probably was incorporated from Neanderthals and selected for for unclear reasons (aesthetic maybe, maybe better protection against rain and cold).