The Genetic Origins of High-Altitude Adaptations in Tibetans

Medical Xpress, February 10, 2014

Genetic adaptations for life at high elevations found in residents of the Tibetan plateau likely originated around 30,000 years ago in peoples related to contemporary Sherpa. These genes were passed on to more recent migrants from lower elevations via population mixing, and then amplified by natural selection in the modern Tibetan gene pool, according to a new study by scientists from the University of Chicago and Case Western Reserve University, published in Nature Communications on February 10.

The transfer of beneficial mutations between human populations and selective enrichment of these genes in descendent generations represents a novel mechanism for adaptation to new environments.

“The Tibetan genome appears to arise from a mixture of two ancestral gene pools,” said Anna Di Rienzo, PhD, professor of human genetics at the University of Chicago and corresponding author of the study. “One migrated early to high altitude and adapted to this environment. The other, which migrated more recently from low altitudes, acquired the advantageous alleles from the resident high-altitude population by interbreeding and forming what we refer to today as Tibetans.”

High elevations are challenging for humans because of low oxygen levels but Tibetans are well adapted to life above 13,000 feet. Due to physiological traits such as relatively low hemoglobin concentrations at altitude, Tibetans have lower risk of complications, such as thrombosis, compared to short-term visitors from low altitude. Unique to Tibetans are variants of the EGLN1 and EPAS1 genes, key genes in the oxygen homeostasis system at all altitudes. These variants were hypothesized to have evolved around 3,000 years ago, a date which conflicts with much older archaeological evidence of human settlement in Tibet.

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The researchers found that, on a genomic level, modern Tibetans appear to descend from populations related to modern Sherpa and Han Chinese. Tibetans carry a roughly even mixture of two ancestral genomes: one a high-altitude component shared with Sherpa and the other a low-altitude component shared with lowlander East Asians. The low-altitude component is found at low to nonexistent frequencies in modern Sherpa, and the high-altitude component is uncommon in lowlanders. This strongly suggested that the ancestor populations of Tibetans interbred and exchanged genes, a process known as genetic admixture.

Tracing the history of these ancestor groups through genome analysis, the team identified a population size split between Sherpa and lowland East Asians around 20,000 to 40,000 years ago, a range consistent with proposed archaeological, mitochondria DNA and Y chromosome evidence for an initial colonization of the Tibetan plateau around 30,000 years ago.

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The team also found that Tibetans shared specific high-altitude component traits with Sherpa, such as the EGLN1 and EPAS1 gene variants, despite the significant amount of genome contribution from lowland East Asians. Further analysis revealed these adaptations were disproportionally enhanced in frequency in Tibetans after admixture, strong evidence of natural selection at play. This stands in contrast to existing models that propose selection works through new advantageous mutations or on existing variants becoming beneficial in a new environment.

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In addition to the EPAS1 and EGLN1 genes, the researchers discovered two other genes with a strong proportion of high-altitude genetic ancestry, HYOU1 and HMBS. The former is known to be up-regulated in response to low oxygen levels and the latter plays an important role in the production of heme, a major component of hemoglobin.

“There is a strong possibility that these genes are adaptations to high altitude,” Di Rienzo adds. “They represent an example of how the ancestry-based approach used in this study will help make new discoveries about genetic adaptations.”

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  • Homo_Occidentalis

    Living beings can and do adapt to their natural environments, even over remarkably short periods in evolutionary terms. This is a common sense conclusion, but in liberal la-la land it’s forbidden knowledge. A simple public acknowledgement of the fact that humans have evolved in the one hundred odd millennia since we left Africa can destroy your career if you’re not careful.

    • JohnEngelman

      It is safe to acknowledge cosmetic evolution, but not the evolution of traits linked to evolution and behavior.

      • Homo_Occidentalis

        Perhaps, but God help any scientist who fixates on it.

    • T_Losan

      unless you’ve found whites to be inferior in some respect, then it’s fine.

  • Erasmus

    They need to go back and recheck their work. Everyone knows that all humans are exactly the same, and to suggest otherwise is racist.

    Don’t dey no nuffins?

    • Edruezzi

      All humans are NOT exactly the same.

  • BonV.Vant

    I remember hearing that the genetic adaptations of Tibetans allow them to have normal birthweight babies at their altitude while people from populations who migrated recently from low altitudes, without the genetic adaptations, have very low birthweight babies when in Tibet. This would mean this would be a very strong instance of natural selection. If the children without the adaptation do not survive childbirth or infancy then that is indeed a very strong “selector”.

  • bigone4u

    The Chinese genocide of the Tibetans may go for naught if the Chinese lack the genetic adaptations needed to live at high altitudes. I once knew a Mexican girl who moved from San Antonio to Denver and experienced constant nosebleeds, so had to move back. She probably would have hemorraghed to death in Tibet. These genetic studies are interesting, although some of them posted on Amren are beyond my ability to comprehend.

    • dd121

      Most of the minor nosebleeds in Denver are from a lack of humidity, not altitude. But I have seen people get altitude sickness at my cabin in Fairpay which is at 10,000 ft.

      • itdoesnotmatter

        Heading for Ouray, CO, two Advil are essential upon my leaving Durango. The Red Mountain Pass is >11,000 ft.
        A splitting headache develops and lingers at 10K ft until acclimation, which takes about 3 days.
        Same with 4 wheeling the Imogene Trail from Telluride to Ouray. The first time, between a headache and the impossible trail, it was on the edge of not being fun.
        Imagine the acclimation required when climbing pulmonary edema altitudes of the Himalayas.

        • dd121

          Try to spend a day in Denver before going up to the high country. You may avoid the headaches. Drink plenty of water and no alcohol. People have developed edema at 7500 ft and died. I’ve been over Imogene, Ophir and up Engineer Mountain. Fun times, no annoying blacks to deal with!

          • itdoesnotmatter

            dd, we have a policy of avoiding big cities, traveling on interstates in favor of secondary or tertiary roads. Durango is overrun with bikers and tourists these days, so staying there is not so hot.
            Will consider another lower altitude town before ascending. Thanks for the advice. Appreciate it.
            I have done Ophir, Engineer and a few others too! Your are so right, only Whites met on those trails.

          • http://www.amren.com/ Michael Christopher Scott

            We like Pagosa Springs. My wife is Japanese, and they’re fond of hot springs. Pagosa has a good one on the grounds of one of the hotels there.

          • itdoesnotmatter

            I haven’t missed too many Colorado, Idaho, Montana spots, Michael, including white water rafting the Payette, other rivers.

            Yes, visited Pagosa, but did not stop in the hotel. It is a lovely area all around.
            One of the most out of the way, unique Colorado places ever visited, [actually stumbled upon], was a miniscule valley village called Paradox, near the Utah border. Camped above it near a lake, enduring a serious lightening storm with strikes forking to the nearby ground. The hair on my arms stood at attention, the atmosphere was so charged.

            Not sure if the Eureka tent poles were potential lightening attractors, spent the night in the Rover.
            Back home, called LLBean who could not give me a straight answer on the tent pole question.
            Some time later, the same thing happened again camping above Yellowstone.

          • Katherine McChesney

            I enjoyed skiing Purgatory near Durango. It took me a couple of days to adjust to the altitude. Headaches and nosebleeds were usual the first day I went up to the top of the mountain.

        • http://www.amren.com/ Michael Christopher Scott

          We moved to Colorado’s Front Range in 1972 when I was six, and it took most of the summer before I was acclimated. I got nosebleeds and headaches. Now I like to take visitors to the top of Pikes Peak and challenge them to footraces there. My wife had trouble here as well, at first. We consider 6100 feet as “low elevation” now.

      • Who Me?

        I had nosebleeds the whole 4 years we lived in Colorado. I don’t know if it was the altitude or the dry air, I always thought it was the altitude.

        • dd121

          I ask my friends who complain of nosebleeds here if they have a humidifier on their furnace. They invariably say no.

    • Anna Tree

      Tibet for Tibetans, I agree but could you please give me some support of a Chinese genocide of Tibetans? Thank you.

      What I found is that there was no attempt of extermination, that only Monks have been killed and their monasteries burned but not the other Tibetans. This has been done to millions of Chinese, it seems only the muslims Chinese have religious rights and are not forced to miscarriages etc.

      There was and still is a forcing of the Chinese culture but strangely this has in fact given more rights and freedom to the Tibetans: Tibet under the Dalai Lamas, including the last one, was a brutal theocracy. Tibetans
      were persecuted by the Tibetan monks and were their slaves. The Dalai Lama
      or his flock claimed he was a living god: for example he was using a farmer’s back
      as a step to get into his carriage!

      Why is it only monks who immolate or demonstrate against China? Where are the demonstration of the
      normal Tibetans, the farmers? It seems to me they prefer the Chinese
      rule over the Monks’s rule. Maybe the less evil…

  • Spartacus

    Race is just a social construct, so this article is clear proof that White Supremacy is alive and well in medicine .

  • http://www.amren.com/ Berserker

    I remember seeing on TV some Tibetans carrying gigantic backpacks (they looked like circus tents folded up). They were climbing in the high altitudes with their pipe-cleaner sized legs and were outworking the non-Tibetans by a mile. I was very impressed by their show of endurance.

    • http://www.amren.com/ Michael Christopher Scott

      There are some foot roads in China that are still officially closed and now heavily overgrown, but on which men used to portage heavy loads. No mules – just men.

    • itdoesnotmatter

      The endurance of these high altitude people is phenomenal, a state of being we reactive Westerners cannot comprehend, but would do well to observe.
      Tibetan and Nepalese Mahayana Buddhist tradition monks regularly walk barefoot in the snow. The head monk told me the monks’ inability to feel pain, discomfort, and avoid frostbite from walking on freezing ground was due changes in their neural structures that mediate sensory input, a phenomenon wrought by hours of meditation achieving “no mind.” The brain registers only sensation, it is “mind” that catalogs and labels sensory input as pain, pleasure, pressure, suffering, etc.
      I am not of this tradition, though have experienced life-changing, invaluable teachings from their masters.

  • LovelyNordicHeidi

    “Due to physiological traits such as relatively low hemoglobin concentrations at altitude, Tibetans have lower risk of complications, such as thrombosis, compared to short-term visitors from low altitude. Unique to Tibetans are variants of the EGLN1 and EPAS1 genes, key genes in the oxygen homeostasis system at all altitudes. These variants were hypothesized to have evolved around 3,000 years ago, a date which conflicts with much older archaeological evidence of human settlement in Tibet.”

    I wondered already what enabled them to get no miscariages at that altitude.

    How can anyone still believe in race in the year 2014! Genetic differences are just social constructs, because race is a social construct! That’s sound logic, of course!

    • jeffaral

      Yes, it would be very hard, If you are a man and had to choose between LovelyNordicHeidi and Hussein Obama’s half-monkey wife Michelle….We’re all the same….

      • LovelyNordicHeidi

        It’s so obvious! Me vs. that woman shows that we’re all EQUAL! Of course, Nordic = Mulatto! I mean, even liberal atheists can explain this supernatural phenomenon to you with their infallible logic!

  • IstvanIN

    This means we can breed humans for specific traits. Thus why blacks are devolving even faster in 1st and former 1st world nations like the US, SA, Rhodesia, we not only support the breeding of blacks but the mass breeding of the worst of them. And since black women have no standards when it comes to the men who knock them up, the actually self-select to devolve.

  • LHathaway

    Girls will only be impressed if they can win the 10,000 meters, or knock some person out they don’t like with one punch. In a world ‘free to allow feminism’ it’s all about having the important traits. . . .

  • Anna Tree

    I read the two articles called “Sinicization of Tibet” before. I didn’t find anything supporting or opposing their claims (beside it doesn’t talk about a genocide as in mass-killing of the population to eradicate or replace them, more about a cultural genocide and that also without bringing any support). It seems to be about territory, about monks killed while fighting and monks who fled and Chinese moving to live in Tibet. Not different from what happened in Europe (and Eastern Europe) between Europeans of various ethnicity and religions. Beside, not all wars are genocide or are done for this purpose, sometimes it is really just political, not saying it is not bad, just saying it is not a genocide: that was done in all China, to all Chinese, not only the Tibetans.

    What I think is that it is a lot of “he said, she said” and I can’t buy the mantras of the left as I did in the past so I need proves to make a (final) opinion, right now I see it as one of the numerous dogmas of the liberal leftist secular religion brainwashed on the whites, this one may be true or may be, like so many of the other anti-white dogmas, not.

    Nobody said that the muslim Albanians did genocide to their neighbors when they actually did, and this was about forcing islam, enslaving, raping and mass-killing, but Hollywood never cared and on the contrary like our governments, they accused the Serbs and Orthodox Christian Croats and Bosnians of being the ones who are genociding. Nobody indeed say that non-whites are genociding us whites in our white countries and here again actually, the whites are the ones accused of genociding the others! I think the Chinese are vilified by the media/politicians/stars because if it fashion, it is a Buddhist thing and it is politically correct. It goes very well with the adopted black child. The fact remain Tibetans were slaves under Dalai Lama and have more freedoms under China and only the monks resist the Chinese.

    “In 2008, Professor Robert Barnett, director of the Program for Tibetan Studies at Columbia University, stated that it was time for accusations of cultural genocide to be dropped: “I think we have to get over any suggestion that the Chinese are ill-intentioned or trying to wipe out Tibet.”[31] He also voiced his doubts in a book review he published in the New York Review of Books: “Why, if Tibetan culture within Tibet is being ‘fast erased from existence’, [do] so many Tibetans within Tibet still appear to have a more vigorous cultural life, with over a hundred literary magazines in Tibetan, than their exile counterparts?”[32]”

    You quoted “The objectives of such a plan would be disintegration of the political and social institutions, of culture, language, national feelings, religion, and the economic existence of national groups, and the destruction of the personal security, liberty, health, dignity, and even the lives of the individuals belonging to such groups.”
    I agree that the above is genocide (and that this is done very slowly to us whites, and I can support this claim), I disagree though that this is done to the Tibetans. I am ready to change my mind if you support your claims: with decades of Western activism, it should be easy to find support, I didn’t find, maybe you had?

    • Lada Belyy

      Raphael Lemkin coined the word genocide and I quoted part of his explanation of what it is. It does not have to be mass killing. Read it again, repeatedly until the veil of denial is lifted from your eyes. It is the destruction of a unique group of people, in whole or in part.
      When the result is the destruction of a distinct group of people, in whole or in part, whether you kill them off, breed them out, relocate them, prevent them from reproducing, whatever means is used, it is genocide.

      • Anna Tree

        I know what Lemkin wrote, I quoted you quoted him in my last paragraph. I just want some support I can check about the “killing off, breeding out, relocation” etc, notably showing that all this is done only to Tibetans and not to other Chinese (the one child policy for example, was only promoted in Tibet.) From what I read, the Chinese do these things to everybody except maybe the muslim Uyghur.

        60 years of this genocide you’re talking about plus Tibet being always on the news thanks to Hollywood and Dalai Lama’s popularity, you must have a lot of support to show me! Please do, thank you. I am nor Chinese neither Tibetan, nor communist neither Buddhist: I have no interest to be on this or that side. I am just a truth seeker and for that I need information to make an opinion. I didn’t find any supporting your claims, you say you want to lift the “veil of denial” from my eyes, you say there are plenty of documented evidence, so PLEASE give it to me, thank you.

        Also think about it how can the Tibetans be still more than 92% of the population after allegedly 60 years of genocide? Surely, the almighty Chinese could have genocide less than 2 million Tibetans 60 years ago or since then, if they wished it, there was no foreign media back then, no?
        On the contrary, for example in 60 years the white population in the US has dropped from 90% to 60%.