Shadows of phenotypes lost

By Razib Khan | July 22, 2011 11:58 pm

I have posted on the existence of blonde hair amongst some Melanesians before. There are natural chemical treatments as well as extreme malnutrition which can result in blonde hair in dark skinned people. The latter seems unlikely from the photos I’ve seen (the lightening of hair due to lack of food has been reported in African refugee camps). In regards to the former I’m confused as to why chemical treatments would be common among Oceanian people as disparate as Solomon Islanders and central desert Australian Aborigines, and yet not among many other east Eurasian populations.


In any case, in response to this comment below on Negrito appearance, I started using google images, and I stumbled upon something strange. In my Malaysian Negrito sample there’s a division between two ethnic groups, Kensiu and Jehai. The Kensiu have hardly any Austro-Asiatic or Austronesian admixture compared to the Jehai. When I looked for images of the Kensiu I came upon on this page, which seems to relate an experience of an aid worker in an isolated Malaysian village. The inhabitants were ethnically diverse, some Malays, but indigenous Negritos a well. Well, it turns out that some of the Negrito children don’t have black hair.

I have no explanation for this phenomenon. The Pan-Asian SNP data set is rather thin on markers, so looking for functional variants isn’t usually fruitful. At least not manually.

Below are some blonde Solomon Islander children singing about Jesus…. ((via Western Confucian)

  • EmmaZunz

    Hi Razib.

    Where I’ve lived in Vanuatu, blonde hair is not uncommon among the children but very rare among the adults. I don’t know if different islands or villages have different rates of blondeness.

    There are also quite a few albino people in Vanuatu – don’t know if that is somehow related.

    EZ.

  • Joe

    Some Hmongs have blond hair too.

  • Garvan

    Cambodians also dye children’s hair with reddish brown colors, so it can be very difficult to tell if the light colored hair you commonly see in children is caused my poor nutrition. Black hair in adults can also fade if up-protected from the sun, giving shades like those you see in the photographs.

    Garvan

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

    so it can be very difficult to tell if the light colored hair you commonly see in children is caused my poor nutrition.

    it’s not poor nutrition. unless different populations react differently to poor nutrition. the hair lightening occurs under extreme deprivation. i’ve seen plenty of people with poor nutrition in bangladesh, and none have non-black hair.


    Where I’ve lived in Vanuatu, blonde hair is not uncommon among the children but very rare among the adults. I don’t know if different islands or villages have different rates of blondeness.

    that’s what you’d expect for a real genetic trait. melanin production tends to increase with age, especially in males.

  • http://blogs.scientificamerican.com/crude-matter/ EcoPhysioMichelle

    melanin production tends to increase with age, especially in males.

    What causes it to happen the other way, then, especially in half-Asians? I am thinking of several exes in particular, who had nearly black hair as children that lightened to merely dark brown during puberty. (Mine went from blonde to brown. I was full-on blonde until about ~8, then dirty blonde, then finally dark brown around junior high.)

  • steve

    I’ve seen blond hair in Samoans, with no known history of European ancestors. The Samoan phrase is “ulo pa’ave” if I remember correctly. The color is dark blond shade, a little different from anything I’ve ever seen elsewhere

  • Justin Giancola

    Maybe Neanderthals/Denisovians had hair shades verging on yellow more than orange… or had the super fair hair as children trait…the mystery continues…dun dun da…

  • Sandgroper

    Please get our name right – it’s Denisovans.

  • Justin Giancola

    your name?! ;p did you coin it? or do you live in the cave?

  • Sandgroper

    Denisova -> Denisovans

  • Justin Giancola

    I know man it was a slip. ya gotta call me out in public? you couldn’t pull me aside? ;)

  • Sandgroper

    My ancestors, bro.

    I’m sensitive, you know? They mean so much to me.

  • http://washparkprophet.blogspot.com ohwilleke

    While the case that this could be a shadow phenotype are real, so is the possibility of cryptic Northern European ancestry. There was interaction with Europeans for several centuries on a sporadic but regular basis before birth record data was established and there would be reasons for records to be falisified or denied. Negrito-European mixes are rare enough that there isn’t a lot of good intuition about what a normal mixed race kid looks like in that context.

    Until a light hair gene in light hair Negritos is pinned down, the admixture v. deep ancestry is hard to resolve.

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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

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