Understanding EDAR

The east Asian EDAR mutation is screwy: it does too many things. It causes increased scalp hair thickness, shovel-shaped incisors, an increase in the number of eccrine sweat glands, and smaller breasts. Which of these seem likely to confer a few-percent advantage?  Why, none of them, of course.

Normally, an advantageous mutation does something useful and not a whole lot of anything else.  That’s because change in a trait is usually bad – it moves you away from the Darwinian optimum.  Coming up with an improved version of one trait is unlikely enough, and usually happens only in a new environment, where the selective pressures have changed.  Coming up with multiple significant changes that are all neutral is most unlikely.

Now if the side effect is in a trait that doesn’t matter anymore, you might get away with it.  For example, a mutation that has a favorable effect X while making you pale works in northern Europe.  The paleness itself may even be advantageous.

Pardis Sabeti thought that extra sweat glands might have been the advantage.  Joshua Akey suggested sexual selection – a preference for thick hair and small breasts. Kamberov thought different effects of EDAR might have been favored at different times.

They are all wrong.  Am I really supposed to believe that you needed to sweat more in ice age China than in Africa?  Breast size already varies – if for some mysterious reason human sexual fashion came to favor smaller ones,  selection on standing variation could have done the job without changing your hair and teeth and sweat glands – changes  that would almost certainly be disadvantageous..  The idea that different effects  conferred advantage at different times is also a nonstarter: any single positive change is very unlikely, and I’m suppose to believe in several?

It’s gotta be something else, an effect that we don’t know, and it must confer a substantial advantage.

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111 Responses to Understanding EDAR

  1. Sandgroper says:

    The only things I could think of were: 1. China was humid throughout this period, so sweating the same way would be less efficient in body cooling. Chinese tend to sweat a lot less than Europeans and Africans, maybe because there’s no point sweating buckets when it’s too humid for the sweat to evaporate. 2. Something advantageous to do with lactation. I vaguely recall something about how Chinese mothers produce a smaller volume of milk than European mothers, but it has just as many goodies in it.

  2. Anonymous says:

    Yes , that Afghan girl with green eyes whose photo was included in 10,000 YE, because it was er, eyecatching novel. The gene for those eyes spread because it is for something else not a novel eyecatching appearance. That is why so many people have green eyes And Chinese women’s hair isn’t distinctive, just because you can, er, tell at a glance a girl is Chinese at 50 yards just by by her long hair. proves nothing. I could read that at Slate “Another Dingbat Sexual Selection Theory Beware of evolutionary explanations that rest on what men find attractive.”

    It seems I have read about some rather remarkable rumps (and other things) in the Bushman females, must be for something else, or Europeans would have it. Whoops, I forgot Europeans’ characteristics are for something else, as I read on Slate, and West Hunter.

  3. dearieme says:

    If in doubt blame pathogens. From what did they need protection?

    • Count Doofus says:

      Indeed, EDAR RNA is expressed particularly in T lymphocytes (which may explain retention of functional thymus in adulthood among Mongoloids) and would corroborate pathogenes hypothesis.

      It also looks to influence pancreas (I suspect interaction with Lipase activity) and adrenal cortex, which may be related to neuroticism levels reported in far eastern peoples.
      I remember news about increased Omega 3 content in Asian female breast milk, but i can’t find a source.

      Also them appear to have more sebaceous glands, along the increased sweat ones, explaining the greasy hairs and oily skin. I cannot tell the evolutionary purpose of such, but i think belong to neoteny. Probably also improved lipidic metabolism is related to neoteny.

      Since it appear to have rise in a warm and humid environment, probably similar to the currently inhabited by pygmies, I say it was useful to extract more resources from a calorie-poor environment and protect from the fast replicating microorganisms tipical of that place.
      Certainly modern south-east Asia is a huge colture for plagues.

      Do bamboo forests are rich or poor in nutrients?
      Do almond-shaped eyes Khoisan hold a mutated variant of EDAR too?

      • Sean says:

        “EDAR RNA is expressed particularly in T lymphocytes”

        Just noticed that. I should have realised that only someone really smart would choose the name Doofus.

  4. Erik Sieven says:

    Maybe it is just part of the larger picture about “domestication” which took place in East Asia more than in Europe, West/South Asia and Africa. Smaller breasts, less body odor at least hint to the direction of neoteny.
    Talking about sexual selection I would have names less body odor instead of small breasts and thicker hair…but I understand the statistical argument, so it has to be something else

    • Count Doofus says:

      I disagree.
      EDAR mutation is prehistorical.

      Human gracilization is genotipically and fenotipically different from human neoteny.
      The former follow agricolture and enlargement of community, and subsequent increased mutation rate and transmission of deseases along with reduction of interpersonal violence.
      The latter is correlated with increased consumption and following need of fat, due the well know positive feedback between bone marrow and brain growth in pre-humans

      It’s more probable that a preistoric established mutation favoured civilization in Neolitics and historical times, as Cochran hints in the article.
      Which would explain how human beings can survive in the overcrowed environment of Hong Kong, Tokio and Chiba City.

  5. Andrew says:

    Scalp hair thickness is an advantage in cold climates. I know. I slept at 11,000 feet a few times last month and I got cold when my hat came off.

    • Michael says:

      These people could obviously have made all the hats they wanted. So, I don’t think that’s it.

      This allele is especially prevalent in the Americas, so perhaps that is a clue. They seem to have spent thousands of years in Beringia at somewhat low population density.

      If it was a pathogen causing the selection at thus step, that would be a very interesting pathogen. Unless the founding population was already totally EDAR, in which case the pathogen must have been very prevalent wherever the Amerindian population originated.

      So… I will go with a lice or flea associated pathogen. Because these parasites are much more easily seen and picked out of black coarse hair over paler skin, people with the EDAR mutation would have a slight advantage. This could be much more important in cold regions where keeping your clothes on all the time also had a significant selective advantage.

      In fact, this could also explain why only the farmers in Europe were very light skinned. Farmers kept close to animals that carried parasites. Light skin makes for higher contrast.

      • adadwa says:

        “In fact, this could also explain why only the farmers in Europe were very light skinned. Farmers kept close to animals that carried parasites. Light skin makes for higher contrast.”

        But those farmers also had dramatically lighter, thinner hair.

        HBD theorizing never stops being spergy as can be.

  6. BB753 says:

    Erik Sieven:
    “Maybe it is just part of the larger picture about “domestication” which took place in East Asia more than in Europe, West/South Asia and Africa. Smaller breasts, less body odor at least hint to the direction of neoteny.”
    I agree. Gracilization points to domestication.
    Not totally off-topic: Asian phenotypes display adaptations to both sub-tropical (everted noses, slenderness, sweat glands, etc) and subartic (short limbs, vascularity, thick hair, pale skin, epicanthic fold, etc) environments, which I always have found disturbing. The typical bundle of Asian traits doesn´t seem coherent, and yet it´s been very succesful.

    You could either argue that these traits have mingled in the past millenia and now coexist because they aren´t selected against, or explain them away with EDAR, at least partially.

    • Toad says:

      They left tropics before the invention of fire and weaving, so they had to be better at ‘roughing it’?

      • bb753 says:

        It was more like a back migration to the tropics from the North. Asians look like a tropical adapted population fresh from the Subartic area, or rather, like a population that needs to be ready to survivr in both environments.

        • Matt says:

          An idea, but East Asians seem adapted to (and historically inhabit) a mixture of arctic (dry, cold) in the north (and Himalayas) grading through cool continental grading through to humid, subtropical climate (wet, hot) in the south.

          West Eurasians seem adapted to (leaving aside mixture with ASI) and have inhabited arctic (dry cold) in the north grading to cool temperate grading to arid climate (dry, hot) in the south.

          Each group could be somewhat adapted to all of the climatic areas in their range, either by being cosmopolitan within them, or by being relatively recently admixed by groups specialised for subregions.

          The northern regions of each area are somewhat similar in selection pressures – larger yet also stouter versions of southern people in line with Bergman and Allan’s rules, with breathing and other adaptations for retaining warmth and moisture.

          While the south in each area is divergent, for humid and jungle adapted phenotypes in East Eurasia (think semi-pygmy), and dry empty climates with long range foraging and moisture preservation in West Eurasia (think semi-Nilo-Saharan/Australian Aborigine).

        • Jason says:

          The primary adaptations of humans to colder environments are cultural though – tools, fire, clothing, etc., rather than physiological. If people relied on physiological adaptations, they wouldn’t need things like clothes and would have things like thick, dense fur covering their entire bodies. But no humans can survive even mildly chilly conditions without clothes and other tools. Even exposure to temperatures as high as 60 degrees F without dry clothes is dangerous to humans – you start getting things like chillblains and trench foot. Physiological features don’t necessarily map perfectly to climatic conditions.

    • Erik Sieven says:

      “It’s been very succelful” yes, up to know. Comparing todays fertiliy rate of east asians (1-1.5) with that of caucasians (2.5-3) and subsaharan africans (around 6.0), one has to wonder if it is still succesful

  7. Anonymous says:

    Long thick luxuriant head hair, lack of body hair. lack of body odour, and smooth skin. Oh, and pert mammaries that may be smaller but have a smaller proportion of milk producing tissue, like they are there for show. The disease is called Yellow Fever.

  8. pauljaminet says:

    Although primarily involved in ectodermal embryonic development, http://www.ncbi.nlm.nih.gov/pubmed/24070496, this gene is expressed in all epithelial cells during development, http://www.ncbi.nlm.nih.gov/pubmed/12972005, including brain epithelial cells, which are essential to the development of the brain, http://en.wikipedia.org/wiki/Neuroepithelial_cell.

    So I would look to selection on brain development for this one.

    • Count Doofus says:

      Undoubtly EDAR gene is a relevant, perhaps the most relevant to qualitative and quantitative brain differences between Asian and the rest of the world.
      But positive selection for nervous system appear to have happened in most of the northern hemisphere without a major phenotipical change like mongoloid one.
      There are very high chances that this mutation was selected multiple times for various advantages, cognition as the last and most know.

      http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756549/
      This paper evidence a relative reduction of EDAR expression among prehistorical Jomon (Ainu) and Yayoi (modern japanese).
      It also hypothize continuity between shovel dentated Erectus and modern Asian.
      Which would be similar to EPAS gene diffusion among Sherpa peoples.
      In case of Erectus-Sapiens continuity I wouldn’t bet that the first wave of mutation’s diffusion was due selection for intelligence and correlates.

      Unless Go and Tangram are endemic.

      • Count Doofus says:

        Errata corrige: This paper evidence a relative reduction of EDAR expression among prehistorical Jomon (Ainu) “THAN” Yayoi (modern japanese).

    • dave chamberlin says:

      “So I would look for selection on brain development for this one.”
      I favor that over protection from pathogens. 30,000 years ago the population was so small and spread out that pathogens weren’t nearly the problem they are today. If it did influence brain development and it only spread among this regional population than it would become another in a growing list of “don’t ask, don’t tell” subject matters that are best left to trouble making blogs. 🙂

      • Count Doofus says:

        Pathogens have always been a problem, if Red Queen Hypothesis is true.

        Population increase accelerate mutation rate of parasites.
        That condition force living beings to gain more immunitary “velocity/voltage” and loss part of relative “pressure/amperage” , meaning the ability to develope new antigenes quickly in exchange of a more robust response to already know diseases.

        The innovation against the tradition, the possibility against the certainty, the city against the country.

      • gcochran9 says:

        Zoonoses matter, sometimes.

        • Count Doofus says:

          The only way to survive zoonoses is a repeated, short lasting exposure to the equivalent animal pathogen.
          Exactly what fast-digestion predator do after every hunt.
          The human equivalent are Edward Jenner’s milkmaids.

          Current Ebola diffusion naturally ask: we should introduce Africans to fried bat-wings.
          This could doom the rest of non bat-eater, I admit.
          Things could end in the same way of Native Southern-Americans.

  9. dave chamberlin says:

    Have they yet checked to see if this gene came from Denisovans.?

  10. Matt says:

    Pendatically I would say the Asian EDAR morph’s a general gland development increase – it does that same thing, but for lots of traits.

    At the same time as offering a substantial advantage, we can date admixture for Uyghurs at around between 0 AD and 1000 AD.

    Yet, frequency doesn’t seem to sit any higher among the Uyghurs than if you made a mix of the same proportions of present day West Eurasians (or Iranians if you prefer) and Han Chinese.

    Likewise the Hazara people. Potentially also Maris and others with “low” (relatively speaking) levels of Siberian admixture and long enough admixture time for selection to happen.

    • Count Doofus says:

      This lead to the trivial deduction that EDAR mutation is positive for fitness just in a EDARm dominated environment.
      Probably EDARm is correlated to an agreeable and submissive personality, evolutively nefarious in a high competitive and low communitarist situation.
      The reason chinese are communist and have not already sized Earth.

      The body glands provide flexibiity in respect of ambiental stressor, from heat to coldness, from diseases to famine.
      BB753 pointed to the apparently contradictory mixed-environment adaptation of Asians, which can stem from a general increase in the aptitude to adjustment.

      Probably EDARm underlay the differences in personality between Asian and non-Asian newborns.The general tendency of Chinese to accept unpleasant condition like tin-mining and rail-building without opposition may be part of a global proclivity to habituation.

      I can just wonder what Mongolian Hordes would have been without EDARm.

      A question for experts: do central Asia is characterized by large climatical excursions year long?

      • Matt says:

        Leaving aside West Eurasians, one of the real interesting comparisons is to compare Native Americans with South East Asian populations.

        The Karitiana are about 50% North East Asian, and about 50% Ancient North Eurasian.

        They are about 100% Asian EDAR.

        Malays are at around 30% Asian EDAR.
        (frequencies – http://genetiker.wordpress.com/2013/07/25/mongoloid-edar-snp-rs3827760-allele-frequencies/)

        What trait, cognitive or otherwise, of plausible selective advantage is such that Koreans and Karitiana are the ingroup and Malays the outgroup? Such a trait must, I guess exist, but what do we know about the groups in question to say what it is…?

        Are Malays the outgroup for selection for or the trait of cooperative personalities compared with Yanomami, Cheyenne and Northern Han Chinese? If so, it certainly doesn’t follow the pattern of other putative “warrior genes”, where IRC the fierce people like Yanomami are fairly far separated from the Chinese.

        Could always do an admixture study on Uyghurs (like this one for teeth) – http://link.springer.com/article/10.1007%2Fs11427-014-4654-x

        • Count Doofus says:

          Valuable data.

          Karitiana specific case could be ascribed to Founding effect.
          320 people insulated in Amazzonia could very likely be endogamic.
          If this was the case, it would be interesting to check the statistics about unviable offspring and correlated mutation load.

          But Pima make case for 100% prevalence of EDARm in precolumbian Americas.

          Mongoloid phenotype (associated to EDARm) seems the only one diffused from polar regions to equator.
          I remark the increased adaptability and subsequent psychological coping abilities.
          Accepting the hypothesis that body is not separated by mind, that personality stem by same gene that shape muscle, bones and guts.

          The reduced diffusion among Malays may descend by increased competition between mongoloid and australoid, the latter more specialized for peri-equatorial condition, the former more adaptable in general.

          Yanomami/Han case can be easily solved accounting that different genes can and necessarly have different and often opposite effects.
          I.e.we know that Chinese, Korean and Japanese undergone similar selection for civilized behavior as European and we can say that CKJ peoples look much more tamed than German, French and English. Particularly looking individual behavior in respect of group needs.
          See also the cult(ure) of rights and freedom.

          I used to think witnessing centuries of exploration and colonialism:
          “black man belong to Africa, yellow man belong to Asia, to white man belong the world”.
          But it seem that the dominant race is also the meekest one.

          • Sandgroper says:

            Meek??? You obviously haven’t met my wife 🙂

            But I get you on the adaptability thing – the world’s most successful ethnic group are the Han.

          • minoritymagnet says:

            “But I get you on the adaptability thing – the world’s most successful ethnic group are the Han.”

            What abot the Jxxs?

          • Sandgroper says:

            In numbers – from a small beginning, Han have become the largest ethnic group in the world.

          • The fourth doorman of the apocalypse says:

            You don’t really know many Chinese women that well, do you?

            Agreeableness and meek are not traits I would use to describe many of them …

  11. O'Nonymous says:

    Are there any plagues / diseases which hit Europe significantly harder than Asia?

  12. dave chamberlin says:

    On a very slightly related note we have Russian giant Nikolay Valuev, http://news.rin.ru/eng/news///20539/ set for search of Yeti in Siberia. He says he just wants to just talk to one but by the looks of Nikolay tps://www.google.com/search?q=nikolay+Valuev+pictures&client=firefox-a&hs=A4I&rls=org.mozilla:en-US:official&channel=np&tbm=isch&tbo=u&source=univ&sa=X&ei=rw4FVNKnE5CmyATbsYKwCA&ved=0CB0QsAQ&biw=1920&bih=868 my guess is there might be some need for some companionship from his own kind.

  13. DdR says:

    Greg,

    In your post about EDAR in March 2013 one commenter theorized that the advantage could be increased DHA in breast milk.

  14. Greying Wanderer says:

    I think it’s breast milk – admittedly almost entirely based on gut instinct.

    The simplest way to raise average IQ among a population if it was required would be to increase the average skull / brain size (easily done by the people on the righter parts of the skull size bell curve surviving as they moved north.and the others not) but that has a physical limit due to child birth so a plated skull with a small brain at birth that grows rapidly would be a more flexible solution.

    So seems to me that breast milk ought to be a miracle food as far as baby brains are concerned.

    • Sean says:

      Underarm odour is sexual, a smell that is due to testosterone derivatives, and this is most strikingly epitomised by Koreans “WHILE only 2 percent of Europeans lack the genes for smelly armpits, most East Asians and almost all Koreans lack this gene, ”

      Koreans also have very low tetstoterone and other related shortcomings. East Asians have a reduced difference between male and female. and a suite of traits that show rather clearly that sexual selection is involved.

    • Sandgroper says:

      I don’t believe in miracles, but as Foteini Hassiotous says, all those stem cells must be doing something: https://www.youtube.com/watch?v=AdRaBv1A3Mo

    • Kate says:

      Buri, the first Norse god, grandfather of Odin, the grey wanderer, was licked from the salty ice of the void by Auoumbla, the cow (who also suckled the first giant).

  15. karch_buttreau says:
    1. “thick” hair means individual hair strands being thicker, and it is really thick / sparse hair and not dense, which most people associate with “thick” hair.
    2. People are apparently confusing the Asian dry ear wax / low body odor thing with EDAR. They’re separate traits. I’d be interested to find out which came first, though.
    3. Small boobs are advantageous in archery. Big boobs get in the way of a bow, hence the Amazon legends of cutting off the right boob.
    • Sandgroper says:

      Coarse is a better descriptor than thick.

    • TWS says:

      Good gravy how many times do I have to read this? My mom was a ‘c’ cup and my wife is a ‘d’ and both are decent archers.

    • Matt says:

      Yes, there is that confusion with the effect of ABC11. The EDAR variant in East Asians seems to look like it increases development, density and robusticity of glands whereever we’ve looked (albeit East Asians have a low hair count compared to West Eurasians, with a hair count / density like Africans, just much more robust hair).

      As far as I know, at the moment we’ve looked at eccrine glands, salivary, sebaceous, hair, mammary and teeth* and all of them become more robust or dense in some fashion (although to be representative, some of these effects only show up in some studies).

      The ABC11 variant in East Asians seems to decrease apocrine glands activity specifically, or to affect apocrine secretions in a way to make them less volatile. Dry earwax has low lipid content, so has a higher melting point and is crusty and solid unless heat greater than body temperature is applied.

      We haven’t looked specifically at specific effects of the East Asian EDAR variant on apocrine glands. Maybe it increases density / activity? Is it likely that the East Asian EDAR variant makes virtually every gland type it touches more dense except for these?

      • 1540C (the Asian variant of EDAR) doesn’t just lead to shovelling on teeth- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756549/“The 1540C allele also significantly affected PC1 (p = 4.9 × 10−3), which denotes overall tooth size” and “The larger tooth size and the shovel shape of incisors result in greater structural strength, which might have been adaptive in a certain culture in which people use their teeth as tools. “ (is this another dopey hypothesis? – probably. it would fit with how Eskimaux use their teeth and the fact that selection seems to be Pleistocene and not Holocene, but that’s about it.). This result makes sense given that the EDAR variant North East Asians (and in also the EDAR variant carrying particular Native Americans) have pretty large teeth compared to the Jomonese, who appear to have a lower frequency.
  16. RT says:

    Really random shot: Hepatitis C?

    PS: I know it is also prevalent in Africa.

  17. John Hostetler says:

    Specific instances of climate change may be an overly convenient explanation for specific adaptations but it’s no surprise that mammals, terrestrial homeotherms par excellence, possess a protein like EDAR, that helps control a suite of somewhat related traits, relevant to adaptability to climate change in general.

    In cooling trends, a mammal benefits from finer, less sparse hair (a wooly undercoat), larger breasts commensurate with higher body fat and higher nutritional storage capacity, and fewer eccrine sweat glands.

    Conversely in warming trends, thicker, sparser hairs, smaller breasts and more eccrine sweat glands are better.

    The East Asian variant of EDAR apparently arose in central China during a warm, humid period. Makes sense to me. The hair benefits are minor compared to all our unclothed mammalian brethren, but are not totally vestigial in humans. It may even turn out that sinodonty is basically a vestigial form of an ancient mammalian dentition pattern related to differing types and sources of food in warmer versus cooler zones. Alternatively, that may the phenotypic trait that truly came along for the ride.

    Greg has stated, “Normally, an advantageous mutation does something useful and not a whole lot of anything else. . . Coming up with an improved version of one trait is unlikely enough, and usually happens only in a new environment, where the selective pressures have changed. Coming up with multiple significant changes that are all neutral is most unlikely.

    I am speculating that the traits conferred by changes in EDAR, in its mammalian variants anyway, can be seen less as particular things like thicker hair, smaller breasts or more sweat, but better heat or cold tolerance in general. As such few or none of the sub-trait components of a beneficial mutation would be neutral.

    • gcochran9 says:

      China was never warmer than Africa. That matters because anatomically modern humans evolved in Africa, capiche? Nor was China hotter back tens of thousands of years ago than it is now. All of the ideas suggested for the EDAR advantage in that paper were silly, but the sweat gland idea was the worst.

      I think that authors didn’t have the nerve to say that they just didn’t know – but sometimes that’s the best thing to say.

      • Sandgroper says:

        In fact, it’s the opposite effect – China was always humid, and in very high humidity, sweating just doesn’t work at all as a cooling mechanism because it can’t evaporate.

      • Engineer Dad says:

        Yet the African desert contains dry heat.

        I enjoyed my college gym’s dry heat sauna with friends. It’s thermostat was usually set at 170 degrees Fahrenheit.
        Some days, it was set higher. We usually sat motionless in the heat up to 30 minutes at a time, while sweating very little.
        It was not too uncomfortable.

        Ten days ago, I returned from humid Shanghai, China (population: 28 million) to California and was miserable the entire two weeks.
        I felt like a boiled frog.

  18. misdreavus says:

    The comments on this post were exactly what i expected them to be.

    Didn’t even bother reading after the first fifteen or so.

    • Anonymous says:

      Well some people make lots of comments on a thread before they come up with anything worth reading.

      Smell is actually very imporant to women in choosing a partner. So why do Koreans (who can be regarded as an extreme East Asian type) have no testosterone smell, and low testosterone? Is it compensated for by other things? No not really; east Asian men are not especially masculine in other ways. I think there may have been selection for monogamous hard working rice farmers (note EA have a special anti alcohol adaptation) . Chinese anthropologist claim the region’s archaics have shovel incisors. As the gene does a lot of things it probably is selected for one thing, and came from an archiac and was strongly selected for in a particular modern human environment, (a bit like hair colors in Neanderthals being selected for in humans). But like coat colours in furry Neanderthals making redheads (the red hair gene has a huge effect on the skins vulnerabilty to sun), I don’t think EDAR did exactly the same thing in modern humans as it did in archiacs.

    • Yudi says:

      You’re back!? Due to the suddenness and completeness of your departure I had started to think you were no longer among the living…

    • dave chamberlin says:

      Misdreavus has a point. This gene has some positive effect to counteract it’s many negative qualities that pull us away from the Darwinian optimum and none of us has any clue what it is. Whatever it is, it is important. Mouse knock in studies can only tell us so much. I doubt that whatever advantage this gene does confer will be discovered through this method. The differences of mice and men are too great to tell us much of anything about why some of us are Lennie Smalls and some of us are George Miltons, the two lead characters in Stienbecks classic “Of Mice and Men”.

      • Count Doofus says:

        ABCC11 gene, the one of odourless armpits, conteract some of the effect of EDAR. In details, it reduce hormonal uptake and thus activity of some tissues.

        Both certainly contributes to neoteny in male and female, in different ways.

        Here the tissuitary analysis:

        The expression on liver is remarkable.
        Also presence on brain, breast and genitals is important.
        Thyroid and adrenal cortex look merely relevant.
        I want to remember that this gene reduce sexual hormones activity in reported organs.

        The equal effect upon males ad females rule out sexual selection.
        Differently by hair colour genes this one wreck both genders.
        Without ABC11 all female asians would be scented Hitomi Tanaka.

        The drying effect on earwax reported by Mat point to the relevance of fatty acid and related metabolism.
        Do central asia is particularly poor of Omega 3? Do America the same?

        Anyway, to resume current hypothesis on EDAR:
        neoteny “unless you turn from your sins and become like little children…”;
        pathogens “and you can’t fail”;
        cognition “racist”
        group adaptiveness “bundled cranes are stronger than the strongest wood”;
        the reader’s idea “wrong until proven wrong”
        the right one “file not found”.

        On slightly different note, the concomitance with Alcohol Dehydrogenase hyperactivity and Aldeide Dehydrogenase hypoactivity among east-asian and the diffusion of the former in Persia and limitrophes makes me wonder if this genes had any correlation with hypotetical rice bounded parasites and generally humidity related one.
        Until the end of the last warm period Iran was much wetter than now.

      • Anonymous says:

        “For example, a mutation that has a favorable effect X while making you pale works in northern Europe. The paleness itself may even be advantageous.”

        The only gene that makes the skin noticably paler as a side effect is the red hair one. But nowhere in nothern Europe do most people have the gene for being red haired. So whatever the advantage EDAR confers actually is, it is not similar to a gene for an advantage, with a paler skin as a side effect (or vice versa). . However red hair must be because if paler skin is an advantage in and of itself in northern Europe; almost everyone there would have the redhead gene, and they do not. OK, EDAR is not straight sexual selection. that was stupid of me.

        “This gene has some positive effect to counteract it’s many negative qualities that pull us away from the Darwinian optimum”.

        I believe Darwin noticed that many of the differences between races were no use to them at all. The differences are side effects, or because the differences are due to sexual selection with a different focus in different races. Men in black Africans. Women in Europeans. It is hard to believe both these races have a similar Darwinian optimum, but due to genes with positive qualities and different side effects, that they look so unalike.

    • JayMan says:

      @misdreavus:

      Hey good to see you around! Awaiting more of your insight…

  19. Karl Zimmerman says:

    As was noted upthread, I think the key takeaway is that Native Americans, who are a hybrid between a population which had the basal variant of EDAR and the derived East Asian version, are at or close to 100% derived (I suspect basal EDAR is intrusive from post-Colombian contact). In contrast, groups which show Neolithic and later admixture between East Asians/Siberians and other groups (Malays, Uighurs, Hazara, Munda, Finns, etc.) don’t show any selection for derived East Asian EDAR at all.

    What this suggests is while there was some strong selective advantage in the late Paleolithic/Mesolithic, by the Neolithic it vanished entirely. What that advantage is I cannot say, but the conjecture around milk quality makes some logical sense, since agricultural societies wean earlier and feed toddlers cereals, which reduces the advantage of high quality breast milk a great deal.

    • Matt says:

      IRC the Sami seem to have lived in a hunting and fishing way since their ancestors mixed with Siberian EDAR 1540C bearers (some detailed analysis of their haplotypes might help date this). Not sure anything special is up with their EDAR variants. They do have a relatively high lactase tolerance for people who live off hunting and fishing though I think, either trading for milk products could be going on, or something else.

    • dave chamberlin says:

      “What this suggests is while there was some strong selective advantage in the late Paleolithic/Mesolithic, by the Neolithic it vanished entirely.”

      Excellent comment which needs to be emphasized and remembered. I could speculate but that is all it would be, empty speculation. How were we different 30,000 years ago than we are now to make this new gene variant so advantageous in the past but not so any longer. I hope that this question will stew in the minds of better thinkers than I and with the continued advance of genetic technologies I will live long enough to learn why.

  20. Joel says:

    Maybe it makes women like sweaty, thick-haired men, with funny teeth?

  21. RCB says:

    Although I don’t know much about EDAR, I don’t find Greg’s argument very compelling. Yes – most mutations are expected to be deleterious, and a hugely pleiotropic mutation would be very likely so. But we have to condition all of this on the fact that the mutation was in fact selected to high frequency. It seems Greg has calculated P(sum of effects advantageous | many effects), instead of P(sum of effects advantageous | many effects and positively selected). All that is required is that the sum effect of all phenotypic changes yields higher fitness – some may indeed be neutral or slightly deleterious, and it needn’t boil down to a single effect.

    That being said, I have no hypothesis for why the phenotypes Greg listed would be favorable.

    • Count Doofus says:

      This drive us to a change of perspectives and new questions:

      Why EDAR mutation isn’t embedded in humanity as whole?
      If it has many positive effects, none of them principal, and a few neutral or negative ones, why didn’t spread to the entire planet?
      Why we did not gained it from start?
      Why Khoi-San seem to have it, and every other human population apparently lost it in the period between 100KY and 30KY, when asian (and just asian) regained it?

      To be fair, the current spread of Han people from Australia to South America to some African countries to Silicon Valley point to a real overall higher fitness.

      But the problem stand still:
      why we are not all almond-eyed?

      And now for something slightly different.

      Regarding fast growth of Han in agricoltural time, i ask if female asians have a reduced tendency of embryo implant failure and spontaneous abortions rates.

      I often heard that chinese and vietnamese are capable to survive and thrive and work with just a bowl of rice.
      the hyperexpression of EDAR in colorectaladenocarcinoma may indicate an increased efficiency in nutritives adsorbance.

      • gcochran9 says:

        The Khoi-San do not have it. Give it a rest.

      • Sean says:

        “I often heard that chinese and vietnamese are capable to survive and thrive and work with just a bowl of rice.
        the hyperexpression of EDAR in colorectal adenocarcinoma may indicate an increased efficiency in nutritives absorbance”

        Just saw that. Gold star.

    • gcochran9 says:

      It’s fucking obvious that the sum of effects is positive, since the EDAR 370A variant has swept. Your second probability is 1.0 . But that doesn’t mean that the sum of currently known effects is positive. EDAR 370A does too many things, none of them obviously useful and each one a priori likely to have a negative effect. And, if you look closely, there’s no reason to think that we’ve exhausted the range of phenotypic effects, since we’ve discovered a major one (more eccrine sweat glands) only recently.
      This strongly suggests that there’s an undiscovered phenotypic effect that pays the freight – which is what I said. I’d bet money on it.

      As for the idea that the advantage may be caused by more than one phenotypic effect – not bloody likely. I know of a class of mutations for which that may be true, but it’s an unusual case.

      • RCB says:

        Yes – I was referring to the sum of currently known effects. I mean to say that this probability is perhaps not as miniscule as you implied. I didn’t mean to discount your hypothesis that there may be another effect that we don’t know about, and that this is the main driver. I know little about EDAR, so have little to offer there.
        Re multiple effects: It seems to me that the fact that a mutation has spread to fixation would at least increase the likelihood that it has multiple positive effects. If a mutation is highly pleiotropic, and it is selected to high frequency, it is plausible that the number of positive effects is >1. “Unusual,” sure, but again we’re restricting ourselves to the set of strongly selected alleles, not all mutations.
        Out of curiosity – what is that “class of mutations” you are referring to?

        • gcochran9 says:

          Let us suppose that being pale had a positive fitness benefit in northern Europe, at least after the switch to agriculture. (the pre-agricultural guys were pretty dark-skinned.)

          Let us also suppose that there exist pleiotropic genes in the melanin pathway – genes that have an important function in the melanin pathway but also in some other function. Their performance in that other pathway might be sub-optimal because of need to perform properly in the melanin pathway. But if circumstances change so that reduced melanin is favored, those pleiotropic genes are free to change in ways that optimize their other function. Messing up melanin production may offer an extra benefit, icing on the cake. If everything was driven solely by reduced melanin function yielding extra vitamin D, you might expect to see a number of different dinged versions of a given melanin genes, rather like what we see with G6PD mutations protecting against malaria. And we do see lots of different dinged versions of MC1R. But more important paleness mutations like SLC24A5, SLC45a2, and TYR really only have one common derived variant in Europeans.

          • Sean says:

            The red hair gene makes for much lighter skin, and that is a scientifically established fact.

            I do not pretend to know genetics but I understand from reading some of Gregory Cochran’s enlightening ‘ rants’ which Prof. Harpending posted years ago, that evolution improves functioning. Hence still do not understand why if when “reduced melanin is favored” red hair gene people did not supplant blonds in northern Europe. The red hair gene is supposed to have come from Neanderthals, it was not a latecomer. The redhead gene gives much paler skin, the blonde hair gene does not . Nowhere, not even in Scotland, do most people have an allele for red hair. So as far as i can see there never was a time when reduced melanin (in relation to UVB) function was selected for. If there was, then red hair genes would have become almost universal in northern Europe. Why aren’t Sweden or Finland known for redheads?

            Vitamin D production after UVB exposure depends on baseline vitamin D and total cholesterol but not on skin pigmentation.

            EDAR 370A is highest in the Han, it has to be something to do with rice farming, or living just on rice; protein, iron, calcium, vitamin B12 and A are all low in such a diet.

          • ursiform says:

            I seem to recall reading that until a couple of millennia ago there was more millet than rice farmed in China.

          • ursiform says:

            Note that “paler is better” is not the same as “palest is best” if the gene that leads to palest has downsides. People with red hair don’t tan well, and so don’t adjust as well to variations in sun levels. If “palest is best” was a hard rule the albino mutation would have taken over Northern Europe, which it clearly hasn’t, because it has serious downsides.

          • pauljaminet says:

            “We found that in Asian populations, most chromosomes carrying the selected allele also carry four SNPs subjected to helminth-driven selective pressure”. Could be helminth-driven selective pressure changed the genetic background and the Asian EDAR SNP only become beneficial with that altered background.

          • Sean says:

            <a href=""
            FOR thousands of years, China’s farmers have used human manure, or “nightsoil”, as fertilizer (King, 1911). […] Prior to intensive use of synthetic fertilizers, nightsoil was an important fertilizer for nearly all crops, including rice and wheat”

            Wikipedia :”The use of unprocessed human feces as fertilizer is a risky practice as it may contain disease-causing pathogens. Nevertheless, in developing nations it is widespread. Common parasitic worm infections, such as ascariasis, in these countries are linked to night soil, because their eggs are in feces”

          • Sean says:

            “EDAR RNA is expressed particularly in T lymphocytes”. The Count, above .

          • Jason says:

            Asians can’t live just on rice. They get beriberi if they eat just rice. This was a major concern of the Japanese military during WW2.

          • Count Doofus says:

            About helmint driven selection, I point selection for stronger alcohol dehydrogenase and weaker aldeide dehydrogenase as a way to protect from parasites.
            Because acethaldeide gives you ache, but also sterilize your instruments

  22. Greying Wanderer says:

    Say for the sake of argument Europeans had some kind of genetic IQ advantage from something or other and East Asians had some kind of genetic IQ advantage from something or other wouldn’t you expect mixed Euro / East Asian kids to have both unless the advantage was the same – or the advantage was different but used the same mechanism so mixed kids only ever got one version or the other so you didn’t usually get both functional at once.

    If for the sake of argument both Euros and East Asians have adaptations in breast milk that helped baby brains grow and the details of those advantages were different but they used the same mechanism so only one could be functional at a time then you might be able to add the second part artificially (i.e. add the East Asian magic ingredient to Euro baby food and the Euro magic ingredient to East Asian baby food).

  23. athEIst says:

    Are there any plagues / diseases which hit Europe significantly harder than Asia?

    Reply

    Sandgroper says:    
    

    Bankers

    WINNER

  24. Greying Wanderer says:

    @Sean

    “Hence still do not understand why if when “reduced melanin is favored” red hair gene people did not supplant blonds in northern Europe …. If there was, then red hair genes would have become almost universal in northern Europe.”

    There are numerous recorded mentions of the red hair / pale / green eyed phenotype over a very wide area in Western Eurasia. Now those sightings could just as easily have been multiple small isolated populations spread over a wide area rather than one large population over a wide area but as a logical possibility at least – even if not an actual one – you could imagine the red hair phenotype spreading widely for melanin reasons and then being replaced later by an improved tanning version version of light skin which reduced the proportion of the red hair genes especially if those new genes came in a package with other more dramatic advantages – like IQ for example – or malaria resistance or something.

    (This would imply the red hair genes had been selected for at some time in the past but the selection went into reverse since the arrival of the improved version / package. I’m not sure if that would be testable?)

    Is there any critical ingredient connected to breast milk which requires sunlight to synthesize?

      • Greying Wanderer says:

        Yeah. (Unless Vitamin D is particularly critical for baby brains in which case no.)

        • Sean says:

          I would like to talk about vitamin D but unfortunately it would be a very long conversation as I know a lot about it. Really clever people like the Count (a physicist if he is who I think he is) disagree with me about vitamin D. Perhaps I am wrong about vitamin D, but I did OK on this thread.

          • misdreavus says:

            but I did OK on this thread.

            lol no.

          • Sean says:

            Oh I made a fool of myself, but a willingness to make a fool of oneself is the essential prerequisite for achieving anything outstanding. And for me it comes naturally. With the aid of the Count (who may be a middle easterner) I came up with what is a viable contender for solving the puzzle.

  25. Greying Wanderer says:

    Is anything created in the process of tanning that is good for the production of or a component in breast milk/baby brains?

    • Greying Wanderer says:

      I mean anything that is specifically known as being a component or factor in breast milk.

      • Sean says:

        A lack of vitamin D can cause proliferation of fetal brain tissue, that may be why you find a relatively high prevalence of pseudo rickets in Ashkenazi Jews. The biggest IQ gain for a gene is for VS Klotho ( which also makes you live longer). Klotho-deficient mice show increased production of vitamin D and premature aging‑like phenotypes, reversed by lowering vitamin D levels. Anyway, vitamin D is under a lot of constraints and feedback mechanisms ( for one thing synthesis in exposed skin switches off after 20 minutes) obviously evolution does not think it a case of more is better

  26. Anonymous says:

    Just one more observation. Rabbits have wierd teeth and wierd traits related to skin and lactation.

    http://darrennaish.blogspot.co.uk/2006/05/most-freaky-of-all-mammals-rabbits.html

    Seems that in mammals weird teeth & kooky dermis go together.

  27. Pingback: Forever Child (Neoteny and Neurodiversity) | Aegyo Kawaii's Neurodiversity Blog

  28. Jethreezy says:

    What about just genetic drift?

  29. Anonymous says:

    How about cerebral malaria. East Asians before they became East Asians – had to cross the himalayan foothills (Nepal) through Northeast India into Southern East Asia. This area was holoendemic for malaria.Tokunaga ( http://www.ncbi.nlm.nih.gov/pubmed/18065779 ) had previously published that 370A was associated with lower activity of NF-KB, and NF-KB is associated with the severity of cerebral malaria.(http://www.ncbi.nlm.nih.gov/pubmed/19713460)

    Cerebral malaria is primarily found in African children, although many parts of Asia are holoendemic (including Asia) and while p vivax is commoner, in the Himalayas – there is still significant p falciparam.

    As for Khoisan – Other differences are perhaps more surprising – the five Africans all lack a genetic variant that is specific to Africa and that grants resistance against malaria. It’s possible that the Bushmen may not need such resistance (http://phenomena.nationalgeographic.com/2010/02/17/africas-genetic-diversity-revealed-by-full-genomes-of-a-bushman-and-a-tutu/)

    On the other hand Bryk wrote that Positive Selection in East Asians for an EDAR Allele that Enhances NF-κB Activation (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0002209 )

    So maybe EDAR 370A protected against cerebral malaria, and the rest of its effects were simply bystander effects and not due to selection?

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