Blondes of the 'black islands'

By Razib Khan | August 18, 2010 4:07 am

Populations_first_wawe_migrRecently I was looking for images of the alpine biomes of the New Guinea highlands* and stumbled onto some intriguing, though not entirely surprising, set of photographs of individuals from Papua New Guinea. They were noteworthy because they manifested the conventional Melanesian physical type, but their hair had a blonde cast to it. For example, here is a charming blonde boy. The photographer has several other striking portraits of Melanesians with lighter hair at his website. In regards to the peculiar hair color of these people he says: “When you ask the people why there are so many blonde people on the islands, they answer 3 things: they have white ancestors, they receive too much sun, or they do not eat enough vitamins! – Langania village, New Ireland, Papua New Guinea.” There is more discussion in the comments about this issue, some claiming that likely it is the sea water and sun which is producing bleaching naturally. If you look around you will see references to bleaching of hair among some of these people as a cultural trait, though the references tend not to be concrete (many clearly assume they’re bleaching their hair, rather than reporting bleaching). The blonde being at the tips from what I can tell in some cases I certainly don’t reject the explanation that bleaching is a cultural practice among these peoples, albeit for children and women only.

But the peculiar hair color of these populations is noted in the scientific literature as if it is a biological characteristic of these groups, not a cultural artifact. From Molecular genetic evidence for the human settlement of the Pacifc: analysis of mitochondrial DNA, Y chromosome and HLA markers: “The Tolais of New Britain are phenotypically ‘Melanesian’, with fairly dark skin and frizzy hair, some-times almost blonde as in some highland Papuan groups.” Enter Tolai ‘New Britain’ into Google Images and the first few pages have several instances of blonde children, including this cute triplet.

Before we go any further, I want to express my skepticism at the idea that this is European admixture. The loci associated with higher odds of having blonde hair in Europeans, OCA2, KITLG, etc., also result in light skin, and secondarily blue eyes. In other words in Europeans blonde hair is to a large extent one effect of generalized depigmentation. There is no magic “blonde gene” which operates independently from the variants which produce lighter skin, or lighter eyes. Though the outcome is not deterministic, the probabilities make it so that someone who has naturally blonde hair is very unlikely to have dark brown skin, at least in any genetic architecture we’re familiar with in Europeans (e.g., African Americans with light eyes and/or hair, also tend to be light skinned).

But if you want more than my logic above, here’s a STRUCTURE plot from The Genetic Structure of Pacific Islanders:

melanesiastruc

I reedited for clarity. Remember that K = putative ancestral populations. So you’re looking for population substructure, and inferred admixture. I’ve compared the Oceanian groups to French from the HGDP sample. The Polynesians in the sample have clear European admixture, but the Melanesians generally do not. The aforementioned Tolai are one of the groups analyzed in this paper, and contrary to one of their explanations for their high frequency of blondness they do not some to have any European ancestry.

What about bleaching? I will be interested to hear what readers have seen, but to my limited knowledge dark skinned populations in other oceanic environments do not seem to have such bleached hair. But, relatively simple forms of hair bleaching do exist which would be possible for a less affluent population to practice as a rite of some sort, or perhaps for simple aesthetic reasons. I put a modest probability on this being the full explanation for this phenotype, and a high probability for it being some of the explanation.

So let’s move to the most novel explanation: that the populations of Oceania have an independent genetic architecture for the emergence of lighter hair color. For me the biggest factor to weight in this hypothesis’ favor is that to my knowledge there are only two population groups in the world which have an appreciable frequency of lighter hair which are not of West Eurasian origin, and they are the indigenous peoples of Melanesia and the Australian desert (this trait seems to be relatively common in the children of the Warlpiri people for example). As we noted last week these two populations form a natural phylogenetic clade, so it seems highly coincidental to me that both exhibit the unique phenotype of relatively dark general pigmentation, but lightness of hair. Additionally, like Europeans lighter hair color seems to be concentrated among children and women in both these groups, aligning with what we know are the correlations of pigmentation and hormones (males and adults are darker).

One obvious model for the blondeness of central desert Australian Aboriginals is European admixture. But the same problems emerge as in the case of the Melanesians: of presumed European traits only the blonde hair expresses, which is a highly peculiar phenomenon. Additionally, we have a relatively recent report from a scientific perspective on the genetics of this trait among these populations, Joseph Birdsell’s Microevolutionary Patterns in Aboriginal Australia: A Gradient Analysis of Clines. The book is from 1993, and no doubt most of the research was done earlier, so the techniques and analyses may seem a bit crude to us. Birdsell observed that the inheritance pattern of blonde hair among the desert Aboriginals exhibited “incomplete dominance.” He recorded that the frequency of the trait was rather high within these tribes, at least for children and women. Additionally, he observes that people with an eastern Aboriginal parent and European parent usually had brown hair of various shades. But among individuals who had one blonde (at least as a child) desert Aboriginal parent and a European parent the offspring tended to be disproportionately blonde, even if the European parent was a brunette! Finally, he observed that aside from head hair, only the body hair of the forearm was blonde. The rest was dark in these Aboriginals.

From what I can tell Birdsell’s monograph is the only recent scientific exploration of this particular topic of blondism among the peoples of Oceania. Many physical anthropologists record the observation of non-black hair among these peoples, but for most their interest did not go beyond cataloging the fact, or it was an incidental result in a bigger project. There’s still a lot about human variation we don’t know. In regards to human pigmentation most of the puzzle has been completed. This is one piece which remains to be found.

Addendum: Some work on the pigmentation genetics of Melanesian populations has been done. They resemble Africans more than any other non-African group in their genetic architecture of loci implicated in the variation of pigmentation. That would basically eliminate the European admixture model to my mind to explain light hair, and increase the probability of bleaching and/or a different and unknown locus.

Note: Blondism among North African, Middle Eastern, Central and South Asian populations is I believe either simply part of the natural continuum of West Eurasians, or, admixture from Europeans or other blonder groups. I believe that this is even the source of blondism among groups like the Hmong, who have a legend of migration from deeper in Asia, where they may have mixed with West Eurasian populations on the fringes of China proper.

Related: Blondism in Melanesia.

* The highest peak in New Guinea is ~14,000 feet above sea level, and in the higher reaches of the uplands it snows periodically.

Image Credit: Wikimedia

CATEGORIZED UNDER: Genetics, Genomics
  • Pingback: Tweets that mention Blondes of the ‘black islands’ | Gene Expression | Discover Magazine -- Topsy.com()

  • Ponto

    I suppose to those who live in the Old and New Worlds who have never seen other people from other parts of this planet, dark skinned peoples with blond or reddish brown hair must seen extraordinary. To Australians who see many of these darker peoples with lighter hair colors, it is all rather mundane, nothing to write home about.

    I don’t live in the deserts of West Australia but in the arid zone of the Centre in the Territory. Quite a few of the Aborigines here are light haired, mostly children, and some women but it is not rare in men. The Aborigines actually exhibit a wide range of hair colors but mostly in the brown hues to black with some reddish haired people. The skin tone is always dark. It is easy to spot hair bleaching as the trend now with dark haired Aborigines who were never blond is to lighten the hair with peroxide, which gives a color quite different to the normal Aboriginal blond color. I guess they do it to make themselves look young and full of life, like children. I am guessing as I don’t really understand why people bother to dye their hair.

    There must be a genetic reason for the large number of blonds in Aborigine children, and for its usual lack of fastness after puberty with only a few retaining the blondness into adulthood. However whatever the gene involved, Aborigines in the Centre have a natural range of hair colors.

  • Yawnie

    It’s possible the extremes of white skin seen today in Europeans only became necessary when light eye colours appeared (necessary in order to maintain the contrast between the facial skin colour and the lips and eyes ).

    Ancestral Europeans may have had blonde hair before they had white skin or light eyes and hence an archiac strain of dark skinned and dark eyed European with blonde hair may have been responsible for the admixture which has produced blonde hair in Melanesians.

  • Arthur

    Could this blondism in children but not adults be related to the vitamin D requirements in childhood? If so, the incidence should be a bit higher with diet; agriculturalists would show a highe frequency because of the low D content and high interference of grains with D metabolism.

  • Insightful

    Razib, I don’t know much about genetics but is it true that these people of Melanesia are among the least related people (even more so than Europeans) to sub-saharan Africans genetically??

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    Ancestral Europeans may have had blonde hair before they had white skin or light eyes and hence an archiac strain of dark skinned and dark eyed European with blonde hair may have been responsible for the admixture which has produced blonde hair in Melanesians.

    they don’t have european admixture. i already told you that. even if it was ‘archaic’ it would have shown up presumably in more genetic closeness to europeans. as for european genetic architecture, the blonde hair they have now seems conditional on the same genes that cause light skin and eyes.

    http://blogs.discovermagazine.com/gnxp/2007/10/why-white-people-are-so-colorful/

    Razib, I don’t know much about genetics but is it true that these people of Melanesia are among the least related people (even more so than Europeans) to sub-saharan Africans genetically??

    no. the rest of the world is ‘least related.’ no-africans are all on one branch.

    Could this blondism in children but not adults be related to the vitamin D requirements in childhood? If so, the incidence should be a bit higher with diet; agriculturalists would show a highe frequency because of the low D content and high interference of grains with D metabolism.

    if its malnutrition, it has to be a gene-enviro interaction. there are many malnourished people in the world with black hair. also, the central desert aboriginals aren’t agriculturalists, nor they lack for sun. the people of highland papua are gardeners, and physically quite robust.

    it seems bleaching is the most plausible explanation for enviro.

  • pconroy

    In terms of bleaching, the ancient Celts used to bleach – or at least whiten – their hair with lime. It was the fashionable thing to do.

    As a child growing up on a farm in Ireland, I saw people “white washing” the internal walls of out houses (aka barns etc) with a lime/water mixture – the reason was to sanitize the dwellings and to cut down on the transmission of infections in close quarters.

    So it could be that some lime or other treatment is used to cut down on head parasites, and that it is mixed by hand in a tub/calabash/container, then applied to the head. This would account for the fact that the forearms were also bleached – which is very curious IMO?!

  • Yawnie

    “as for european genetic architecture, the blonde hair they have now seems conditional on the same genes that cause light skin and eyes”.

    Yes they are linked now (although red hair goes with noticably lighter skin far more than blonde) but that doesn’t mean they were always linked, does it?

    Ancestors of the Melanesians were in a environment where blonde hair was being selected for, if blonde hair was initially a side effect of selection for light skin how did it become disconnected ? And how did the gene for blonde hair survive? Once it had become disconnected from the advantagous trait of skin lightening genes for blonde hair would be neutral in respect to fitness.

    The alternative is that blonde hair was actually the focus of selection and if that is the case it’s difficult to see what the advantage was apart from attracting attention – sexual selection.

    By the way here is the best evidence for the switch to agriculture being the cause of skin lightening.

    Meat consumption reduces the risk of nutritional rickets and osteomalacia.

    “The mechanism by which meat reduces rachitic and osteomalacic risk is uncertain and appears independent of revised estimates of meat vitamin D content. The meat content of the omnivore Western diet may explain its high degree of protection against nutritional rickets and osteomalacia from infancy to old age in the presence of endogenous vitamin D deficiency.”

    And here is evidence that people with fair skin don’t have higher vitamin d levels ( within Caucasians ) Europeans have higher Vitamin D levels than other people but the fairest skinned Europeans have lower Vitamin D than the rest Pigmentation and Vitamin D Metabolism in Caucasians: Low Vitamin D Serum Levels in Fair Skin Types in the UK

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    Yes they are linked now (although red hair goes with noticably lighter skin far more than blonde) but that doesn’t mean they were always linked, does it?

    what you’re suggesting isn’t logically impossible. it seems unlikely from what i know though. but yeah, who knows?

    Ancestors of the Melanesians were in a environment where blonde hair was being selected for, if blonde hair was initially a side effect of selection for light skin how did it become disconnected ? And how did the gene for blonde hair survive? Once it had become disconnected from the advantagous trait of skin lightening genes for blonde hair would be neutral in respect to fitness.

    just to be clear, we don’t know it was selection for blonde hair. if it’s genetic, we just know that the genes which underlay blonde hair are being selected for. but it is unlikely to impact only one trait. i also didn’t say anything about blonde hair genes in melanesians being connected to skin color ever. we don’t know anything about the genetic architecture (if you do, point me to the research) or gene expression (OCA2 seems to have tissue specific expression variation for example, larger effect in eyes than skin).

  • http://www.evoandproud.blogspot.com Peter Frost

    There is a common genetic condition in New Guinea (called ‘red skin’) that leads to reddish skin and blond hair:

    Walsh, R.J. (1971). A distinctive pigment of the skin in New Guinea indigenes, Annals of Human Genetics, 34, 379–388

    Walsh concluded that “the gene is present in high frequency in some areas in which it must possess a significant survival advantage.”

    This condition would not, of course, account for the photo at the top of this post (a blond-haired individual with dark skin). But the same selection pressure may be responsible, whatever it might be.

    What I find surprising is the co-existence of blond hair with dark skin. We normally see the opposite in our species,i.e., dark hair co-existing with lighter-colored skin.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    What I find surprising is the co-existence of blond hair with dark skin. We normally see the opposite in our species,i.e., dark hair co-existing with lighter-colored skin.

    yep. as you know if you look at the map the area with light skin as modal is far larger than the area with blue eyes as modal which is far larger than the area with blonde hair. it looks like there’s a dosage difference in response across specific tissues. this makes sense developmentally, many individuals who have brown skins as adults have white skin as young infants, but still have dark hair and eyes.

    the pedigree which birdsell reports indicates a really different genetic architecture.

  • Georg

    Hello Razib,
    what is known about the genetics of the “aboriginees” of
    the canary islands, or the Berber people in Morocco?
    (Both were closely related afaIk)
    In both populations there were/are a lot if blondes .
    For the canary island people at least, there never was
    a european admixture befor the invasion of the spanish.
    Georg

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    the canary people were berbers:
    http://www.sciencedaily.com/releases/2009/10/091021115147.htm

    blondism may be a common feature of an end-point in the continuum of west eurasian people. the berbers as just a branch of that.

  • http://entitledtoanopinion.wordpress.com TGGP

    I recall you earlier mentioning some oriental populations near the arctic (cousins of our Eskimos) who had rather European-looking hair, though they may have been just brown rather than black haired.

  • Nador

    I definitely lean toward genetic reasons for the blondness of Melanesians, nevertheless i cant help noticing the grade of the colour of their hair. For example on the photo of the triplets you linked at least two of them have darker hair close to their head/skin than at the outer end. This is somewhat similar to how dyed or bleached hair looks, however i can not see a sharp demarcation that is usual for dyed hair.
    The gradual lightening of their hair towards the end could be explained by melanin not properly binding to their hair. Though i am not sure if that is possible.

  • pconroy

    Yeah, but what about the forearms arms being bleached??

    I have dark brown/black hair on my head, and a red/black beard, so I’m aware that it’s possible to have different colored hair in different areas of the body – but who has ever heard of the forearms being different hair colored to other parts of the arms??

  • Nador

    Well, having different hair coloured forearm is indeed strange for a European, nevertheless inhomogeneous hair colour is pretty common: for example reddish beards among otherwise brown or blonde Europeans are rather frequent. I also exhibit many hair colours: I have dark blonde hair, blonde moustache, reddish beard with some brown parts which also includes some dark brown threads. The hair on my scrotum is blonde while my pubic hair is light brown. I have some lone pieces of hair on my back and shoulders that are black. So i guess it is not so strange to have different hair colours on different body parts.

  • Sandgroper

    TMI.

    Gradual lightening from root to tip is from sun bleaching (prolonged exposure to strong sunlight). Chemical bleaching gives a sudden colour change as it grows out, as you noted.

  • Yawnie

    OK it’s about mice but ‘Skin and hair pigmentation variation in Island Melanesia’is cited by the following paper ( can’t access the full text) so they must think it has some relevance

    Estrogen Increases Hair Pigmentation in Female Recessive Yellow Mice
    ” high dose of androgen increased total melanin content exclusively in male hairThese results suggest that estrogen is the main factor in determining the higher content of eumelanin and pheomelanin in female hair of Mc1re/Mc1re mice”.

    If estrogen or the balance of estrogen with androgen affects the blonde hair of Melanesians that would explain why the males are usually blonde only while they are still children and why women are more often blonde than the men.

  • vuvuvuvuvuvu

    Razib:

    I don’t get why you’d put so much weight on the ideas of european admixture or bleaching to begin with. Melanesia and Australia are a very long ways from western eurasia, so an ancient migration would be astoundingly unlikely. (especially how recently light hair and eyes arose) And recent admixture? Wouldn’t that be really obvious? You mention the following as well, for example:

    “(e.g., African Americans with light eyes and/or hair, also tend to be light skinned).”

    My impression has long been that the expression of most eurasian light hair alleles are diluted beyond a certain point when it comes to darkness of skin. That’s why you so very rarely see light hair among european populations, unless they themselves are also light. It would probably work something like this- the lighter the hair, the more easily it’s expression is diluted by darker skin, where platinum blonde hair can’t really express itself except in very light skinned individuals. (I say this in relation to the normal variation in human skin color, so it excludes red heads and albinos.)

    In fact, I’ve seen references to some eurasian light hair phenotypes, in combination with relatively darker skin tones, to produce copper colored hair. I remember, in 9th grade, knowing a “black” boy with light brown skin, green eyes, and copper colored hair. He had it all year around, so I doubt it was artificial.

    Light eyes don’t seem to follow this pattern whatsoever, (I’ve never gotten much of an impression of it being so much more common in light skinned african-americans either) considering how you see alot of south asians with dark skin and blue eyes. Granted, some dark skinned humans can have a yellowish tone to their sclera. It’s most common in very dark skinned humans, and I’ve seen it in africans, south asians, and dark arabs. I’ve seen older texts refer to this as an ancestral trait, because gorillas have a yellow sclera, but I’ve read it’s simply a pleiotropic effect where some dark skinned individuals can see an excess of melanin in their eyes. It’s an interesting and exotic feature.

    (the similarity with gorillas is probably due to them having jet black skin. Those references probably took place before we were sure chimpanzees were our most recent ancestor.)

    Bleaching is an even more peculiar explanation to give weight to. Wouldn’t it be really, really easy to attest to this being a cultural practice, eliminating any need for a genetic explanation?

    The malnutrition explanations are also peculiar. This trait seems to be very constant, and nowhere else has blonde hair been accompanied by certain forms of malnutrition. Granted, you’ve got Kwashiorkor giving people red hair, but that’s probably seldom seen in whites because the vast majority of whites aren’t born with black hair.

    By the way, which polynesian sample had european admixture? How much was it? When did it come in?

    Yawnie:

    I’m guessing you’re referencing an older Peter Frost post with that. He himself mentioned how there’s virtually no sex linkage with eye color, and either way, that form of sexual selection just sounds ridiculous.

    Peter Frost:

    I’ve of red hair among australo-melanesians, but never it working in a fashion similar to the eurasian red hair phenotype. The eurasian phenotype is well known to typically create very light skin that shows significant blood flow, among other things. What else does the papuan one do? What do it’s effects look like?

    Does anybody know how the eurasian red hair trait expresses itself for individuals who are homozygotic, or heterozygotic for it? (those who are heterozygotic for the red hair trait often experience increased UV sensitivity.)

  • vuvuvuvuvuvu

    Specifically, I’m wondering about there being photographs of papuans with this red hair trait. I’ve heard of red hair being among aborigines, but does it work similarly?

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    #20, #21, there’s a large literature on the genetics of pigmentation now. you should refer to it. as it is, your comment is hard to parse so i won’t try. btw, there are two pigments in hair. one is brown and one is red. the balance between the two determines color. my personal experience is that the brown bleaches out first, so i have copper hair unless i do a second bleach.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    If estrogen or the balance of estrogen with androgen affects the blonde hair of Melanesians that would explain why the males are usually blonde only while they are still children and why women are more often blonde than the men.

    that’s the same explanation for europeans.

  • vuvuvuvuvuvu

    Quick corrections, but when I said “That’s why you so very rarely see light hair among european populations, unless they themselves are also light.”, I meant to say “That’s why you so very rarely see light among populations mixed with europeans, unless they themselves are also light.” And when I asked “Does anybody know how the eurasian red hair trait expresses itself for individuals who are homozygotic, or heterozygotic for it?”, I meant this in relation to people with dark skin. Sorry for that faulty questioning- I obviously know that light skinned people who carry the alleles either have red hair and such, but what I was wondering were it’s effects on people with normally dark skin. Is it anything like what’s seen with the trait in papuans?

    But to the point, why are you so dismissive? Yes, I know about the genetics of hair color. All I’m pointing out is how eurasian light hair seems to be poorly expressed beyond a certain benchmark of skin color, due to a pleiotropic effect, in relation to your point about the genetic architecture of light hair, eyes, and skin among europeans, (it seemed simplsitic) among other things.

  • vuvuvuvuvuvu

    And in regards to your point with copper hair, I was only referring to how I’ve seen references- references I don’t remember, sadly- that, in relation to the pleiotropic effect of darker skin on eurasian light hair, the hair color will sometimes be expressed as having a copper color that’s distinct from the brunette or red hair variation seen among europeans and the like. The african-american individual I knew with this hair color had it the entire time I knew him, so, in relation to the references I’ve seen for it, I doubt it was just due to him bleaching or whatever.

    To specifically clarify, my whole point about the pleiotropic relationship with eurasian light hair phenotypes and skin color, has been your treatment of the possibility of this light hair among australo-melanesians being due to european admixture. You even gave this some consideration back in 05 on your first post on this subject. This, in addition to the paucity of historical evidence for european admixture, and even genetic evidence, is another reason to doubt this trait being due to european admixture.

  • vuvuvuvuvuvu

    Also- I admit I’ve never seen much in the way of academic substantiation for this pleiotropic effect, but think about it. As you yourself note, how often do you see dark skinned individuals with light hair, including brown hair? How often do you see populations with significant european admixture as exhibiting light hair with the sole exceptions of some light skinned individuals?

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Gene Expression

This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

ADVERTISEMENT

See More

ADVERTISEMENT

RSS Razib’s Pinboard

Edifying books

Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »