Wet or dry ear wax?

By Razib Khan | January 30, 2006 2:20 pm

Life can be really funny. When I was in college I was incorrigibly curious and I asked a Korean American friend if his ear wax was dry (I’d read that East Asians had dry ear wax once) and his response was, “Isn’t everybody’s?” When it comes to interpersonal differences there are many things we take for granted and extrapolate to others that aren’t necessarily true.1 Nick Wade in The New York Times has an interesting write up about the genetics of the ear wax phenotype. While the populations of Europe and Africa have wet ear wax, those of East Asia have dry ear wax. Other populations are somewhere in between. Nature Genetics has the original paper (don’t be surprised if the link takes a while to load).
Here are the worldwide distribution of the alleles:
earwaxmap.jpg
The trend is pretty clear, modal in Northeast Asia and decreasing everywhere else. These figures show why the authors assume that selection is at play here, linkage disequilibrium implies that recombination has not had time to break apart the correlations as neighboring portions of the genome were dragged along with the increase of frequency on the single nucleotide of interest. Wade finds a quote from a scientist who says this could be the result of random genetic drift. I don’t buy it, because drift is a default explanation offered by many when they don’t have any other plausible model on hand (runaway sexual selection is another explanation of this sort). The LDE noted above suggests that positive selection was occurring at that locus. One can posit models that generate these distributions via drift, perhaps fixation in a small population which has an enormous demographic expansion into the surrounding populations. This would have had to have happened before 8-10,000 years BP because the New World populations in North America possess the allele. It just seems more parsimonious, along with the LDE data, that selection is at work (rather than reinvent the wheel, here is RPM’s “Detecting Natural Selection” series, I, II, III, IV, V, VI, VII).
The authors posit many hypotheses for why selection for dry ear wax, or, more properly for the allele, A, which in the homozygotes generates dry ear wax, should have increased its frequency in Northeast Asia. To them it seems likely that the ear wax phenotype is a byproduct of pleiotropy, that is, another trait was generating the fitness differentials correlated with this allele, and the fact that it had other phenotypic effects was incidental. I found this “fact” amusing:

They write that earwax type and armpit odor are correlated, since populations with dry earwax, such as those of East Asia, tend to sweat less and have little or no body odor, whereas the wet earwax populations of Africa and Europe sweat more and so may have greater body odor.

The adults I have known who do not need to make recourse to deodorants to ward off body odor have all been East Asian females. No surprise.
Addendum: One point made Wade’s article is that South and Central Asians who exhibit intermediate frequencies of the alleles might have gotten them via admixture. In the case of Central Asians this is plausible, genetically and historically they tend to bridge East and West. I am skeptical in the case of South Asians, it seems more plausible to me that the same selection pressures which benefited the allele in East Asians might have some advantage in Southern Asia, as Indians are not a recently admixed population (at least that the balance of the current research).
Via John Hawks.
Reference: Yoshiura et al. 2006, An SNP in the ABCC11 gene is the determinant of human earwax type, Nature Genetics.
1 – Another example seemed to be that many of the females in my dorm assumed that men had an urge to urinate when they laughed hard, while most of the males were pretty confused about this.

CATEGORIZED UNDER: Genetics
  • http://www.indiancowboy.net/blog IndianCowboy

    funnily enough, in neuro a couple weeks ago we learned theneuroanatomical/physiological basis for women ebing more likely to pee when they luagh than men

  • Ick of the East

    Hmmm, about this dry wax/no BO correlation….According to the chart, Thais are almost totally wet inside the ears. Yet I’ve never met any people with less body odor.
    And how weird is it that Siberians and Australians have no ear wax at all! :-}

  • http://www.scienceblogs.com/gnxp razib

    Yet I’ve never met any people with less body odor.
    i assume there are other factors at work. amt. of washing, use of deodorants and diet come to mind.

  • http://world.std.com/~mmcirvin/ Matt McIrvin

    North America is interesting. How wet is wet? My ear wax is wetter at some times than others, but I’d probably describe it as more dry than wet. My ancestors are mostly European but some are North American.

  • Big Bill

    So Africans have wet earwax/more sweat/more body odor than Asians? Do Asians think Africans have a strong body odor?
    If so, do lefties consider this racism?
    Or is it only racism when white people say it?
    What a fascinating concept: some races really are stinkier than others.

  • http://www.scienceblogs.com/gnxp razib

    Do Asians think Africans have a strong body odor?
    i believe so, though in general i think there is a tendency by the japanese to think foreigners (gaijin) are stinky. south asians often joke that they are particularly stinky FYI.
    oh, and yes, in general P(racism|white) > 0, while P(racism|non-white) = 0. that is, many people think that being white is a necessary precondition to being racist :) i disagree, but what do i know, i’m only a poor colored, racism = race + power, and i by definition have no power!

  • Mark Paris

    Body odor may, indeed, be related to a number of factors, including diet. I seem to remember reading that people who eat a lot of red meat may have a tendency toward greater body odo. That might also help to explain why Japanese, who, I think, do not or used to not consume lots of red meat, might not have as much body odor. There is also the possibility that what is noticed is not a lack of odor on the part of Japanese or the presence of strong odor in Westerners, but rather the presence of different odors in both populations.

  • http://www.scienceblogs.com/gnxp razib

    vegetarians swear by the red meat difference.

  • pconroy

    FWIW, I am from Ireland, and have dry, whiteish and somewhat flaky ear wax, I also happen to sweat a lot, and have been told by at least 2 females that when I sweat, I smell like a horse – don’t know if that qualifies as “stinky” or not, as it depends on whether you like the smell of horses?! But it does seem to contradict some of the findings.
    BTW, I read somewhere when the first Westerners started arriving at the Chinese court in the 16 centuary, the Chinese felt they all stunk of meat. Of course the Spaniards, when they first met the Aztecs, were shocked that they bathed at least daily and often more, as they considered this practise unhealthy, in that it would make a person weak.

  • http://www.scienceblogs.com/gnxp razib

    BTW, I read somewhere when the first Westerners started arriving at the Chinese court in the 16 centuary, the Chinese felt they all stunk of meat.
    i have read this as well. also, i have seen references that dairy products change body odor. i need to do some research and post it!

  • http://letterfromgotham.blogspot.com diana

    I think the 16th century Europeans stunk of bodystench. Has anybody here ever taken a camping trip? It’s amazing what you smell like after three days away from hot running water.

  • Gemma

    Im an english girl (ancestors scottish, irish, english and a tiny bit of swedish) and i have dry ear wax. Ive also never needed to use a deodrant (even when camping!) much to the puzzlement of all my friends, so i find this research quite interesting. I also however have hardly any hair under my arms (literally like two mini ones, again to my friends annoyance) does anyone know if this is related??

  • Horatio

    FYI
    My girlfriend is Caucasian (mostly French) and she never needs to wear deodorant. Even after running a couple of miles she doesn’t smell. She’s also 1/16 Cherokee and she has straight hair similar to East Asians, though much thinner. Along with Gemma, now you know of two non-Asians who do not require deodorant. Unfortunately, I am a sweaty Spaniard who needs to use a lot of old spice to keep my BO bearable.

  • nick green

    i am glad to find out i am not a freak.i am a white english male hard working gardener.i never sweat or wear deodorant.girlfriends have said its not normal,not to sweat.meybe i am not so english?

  • rose

    This is very interesting. My oldest daughter has always had the dry, white flakey ear wax. Early in her life, the doctor recommended ear drops. she hated them. As a young adult, she continues to suffer from dry skin. Her heritage is german, with the exception of a Great-great Irish grandmother. She rarely uses deodrant, while my youngest daughter sweats heavily with an ordor. Does this dry earwax hurt a person???

  • Colleen

    Too funny… I am Irish and Italian, I too have the dry flaky ear wax, and very little body odor. I have to work out really hard to break a sweat. Ironically, I ran across this while researching another topic – the genetic link in susceptability to fungal infections and grain intolerance (which many Irish seem to have).
    If anyone has any evidence of a link between these seemingly random physical traits, please send me an email at:
    gaelgal2005@yahoo.com
    Thanks!

  • BC

    I’m from Singapore. Both my parents are mixed Malay and Chinese and trace of Dutch heritage, though most people would pass me off as either Malay or Chinese. I think I have the dry earwax too. It gets very distracting and annoying to feel the layers flaking, like paint from the wall. I also have dry skin which flakes when I rub my fingers through it.
    Why isn’t it classified as a heridatary disease yet? I’m currently pushing for gene therapy for this condition as opposed to the use of oils, creme, ear drops or drugs. I do not want to be dependant on those for the rest of my life. I rather take the risks associated with that approach for a lifetime cure.
    Brendan

  • daniel

    I’m Korean (male) both ethnically and nationality-wise. I do have BO but barely compared to my other non-Korean friends. I sweat extremely, but this is somewhat of an unusual condition, as far as I know, and have dry earwax.
    Friends of Middle Eastern, British, Irish, French & German ancestry seem to have a similar BO that I recognize immediately, and it’s much stronger BO, which is why it’s recognized. But not all of them have this distinctive smell. Should’ve asked about their earwax. I didn’t know about this until recent and its very interesting!
    I don’t think BO and earwax has too much in correlation to food we intake. But could be true if were talking about food consumed for generations after generations. But, then again, not many people got to eat much meat thousands of years ago, and anyone living on a coast was bound to eat fish. Rose, it doesn’t hurt. Brendan, move to a cooler region and it’ll probably stop.

  • Joe

    At 58 I had a heart attack, and they found I was “Combat Related” diabetic w/Pancreatic disease (all related to Agent Orange poisoning in Vietnam). I am German/English and Irish by ancestry – born in Philly, Pa., spent 30 years globe trotting in the Military, now retired, living in Texas. I am currently on Insulin. Suddenly, within a year of my health degrading, my earwax changed from very wet and gooey to dry and flakey. Also, I never sweated much, and never needed deodorant. Now, I have a BO that wakes me up at night. I must say, I’ve been taken off Red Meat – Beef/Ham forbidden to me. Matter? Also, I had a Vietnamese girl-friend once who told me I tasted sweet and bloody, while she tasted oily and Fishy. That I am certain is related to our standard meals. Not ancestry.

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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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