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Thread: Ancient Dental Plaque And What It Says About Lactase Persistence.

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    2 out of 2 members found this post helpful.

    Ancient Dental Plaque And What It Says About Lactase Persistence.

    This is a link to the article in Science Magazine:
    http://www.sciencedaily.com/releases...1127094944.htm

    A consortium of scientists examined ancient teeth for evidence of beta-lactoglobulin, the dominant whey protein. When making cheese or yoghurt, much of this protein seems to be lost, so this was a way of distinguishing between dairy consumption and actual milk drinking.

    They maintain that it only happened within the last 5,000 years, so 3000 BC more or less, which seems to me to tie into the movement of Indo-Europeans into Europe, but the article also says this: "Professor Dallas Swallow, from the Research Department of Genetics, Evolution and Environment at UCL, added: "It is only within the last several thousand years that genetic mutations arose in Europe, East Africa, and the Arabian Peninsula that allowed lactase to persist into adulthood, a genetic trait that enables lifelong milk consumption."

    Are they saying that the mutation that confers lactase tolerance on the Bedouin and the East Africans also arose in the last 5000 years? What can they have to do with the Indo-Europeans? Plus, those are different mutations altogether, to my recollection, so why would they have evolved in the same time frame?

    I can't find the actual article. If someone has institutional access and can read it, it would be great if you would post any information you can glean as to the precise cultures and dates for it in Europe, and any clarification of their findings about the Bedouin and East African mutations.


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    1 out of 1 members found this post helpful.
    Quote Originally Posted by Angela View Post
    Are they saying that the mutation that confers lactase tolerance on the Bedouin and the East Africans also arose in the last 5000 years? What can they have to do with the Indo-Europeans? Plus, those are different mutations altogether, to my recollection, so why would they have evolved in the same time frame?
    I think that makes sense. Random LP mutations might have happened hundreds of times over human history - if you checked everyone in China or India today I wouldn't be surprised if there were half a dozen different LP mutations in half a dozen individuals just from random mutation - but it doesn't lead to anything unless they're in an environment where being LP is life or death. So the specific one that exists in Europe (and the one in Arabia) are just the ones out of all the hundreds of LP mutations there have been over history that appeared in an environment where it was life or death.

    imo

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    Quote Originally Posted by Greying Wanderer View Post
    I think that makes sense. Random LP mutations might have happened hundreds of times over human history - if you checked everyone in China or India today I wouldn't be surprised if there were half a dozen different LP mutations in half a dozen individuals just from random mutation - but it doesn't lead to anything unless they're in an environment where being LP is life or death. So the specific one that exists in Europe (and the one in Arabia) are just the ones out of all the hundreds of LP mutations there have been over history that appeared in an environment where it was life or death.

    imo
    Sounds reasonable. I also think this article is informative:

    http://www.sciencedaily.com/releases...0122091846.htm

    "But in famine conditions, such as when crops fail, they are likely to have eaten all the fermented milk foods, leaving only the more high-lactose products. This would have caused the usual lactose intolerance symptoms such as diarrhea. Diarrhea in in healthy people is not usually life-threatening, but in severely malnourished individuals it certainly can be. So famine could have led to episodes of very strong natural selection favoring lactase persistence."

    In this regard, I find it interesting that recent studies found that the Pontic-Caspian steppe people were nutritionally stressed as children, and that the Finnish population went though an extreme bottleneck. Those sound like famine conditions to me.

    In situations where crops couldn't be grown, or suddenly failed, and people were limited to a more pastoral diet, the ability to digest fresh milk would have been a definite advantage, although it might have taken quite a while to spread widely in a population. This would explain why the herders on the steppe had such deficits in nutrition in childhood. It also would have taken time to figure out how to keep the animals lactating all year long.

    I think people also forget that it's taken thousands of years to reach current levels even in northern Europe. While in Germany about 70% of the people in one area carried it by 1200 AD, in neighboring Hungary in 1000 AD, the figure was only 33%.

    I think this study on it is pretty good, as it's pretty recent, and provides a nice summary of the literature.
    http://www.plosone.org/article/info%...l.pone.0086251

    "The culture-historical hypothesis posits that the LP allele arose from low frequency through selection in cultures with a long history of dairying. By contrast, the reverse-cause hypothesis holds that the LP allele may have already been common in certain populations due to genetic drift and only these populations would have adopted the cultural practice of dairying. Additional genetic pressures may have existed in arid climates where milk is one of the only clean sources of water [27] or in northern latitudes where, in the absence of vitamin D, the presence of lactose facilitates the absorption of calcium by the intestinal mucosa and thus reduces the risk of rickets and osteomalacia [28]. Rickets and osteomalacia can cause deformation of the pelvis and are leading causes of obstructed labor and consequent maternal mortality and perinatal morbidity in traditional societies without access to modern medical care [29]."

    Ed. Given it's distribution, and the fact that it was found in the Basque Neolithic samples, I think there's a question whether it expanded from the Steppe or from Iberia, perhaps with mtDna "H"? That's why it would be interesting to get access to more of the data from the study in the OP.

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    Speaking of huge famine, there was one after 536 AD. About 50% of people died around Baltics. Poland got depopulated.
    Only Finns did not loose population. Which was explained by them not relying on agriculture that much.

    But I wonder if Slavic survival and further expansion, which happened around same time, was helped by LP at least partially.

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    Quote Originally Posted by arvistro View Post
    Speaking of huge famine, there was one after 536 AD. About 50% of people died around Baltics. Poland got depopulated.
    Only Finns did not loose population. Which was explained by them not relying on agriculture that much.

    But I wonder if Slavic survival and further expansion, which happened around same time, was helped by LP at least partially.
    And the Black death killed 1/3 of the population of most of Europe. Everyone in the world is probably descended of the 50% of those in their ancestor pops who survived death periods because of war, starvation, disease or whatever.

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    Yep, the point however was that unlike black death or wars, 536 and following years was about agriculture failing due to climate. Which only later got followed by Justinian plague.
    So milk drinking may have helped to survive and may have increased milk drinker %, also as late as 6th century.

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    Quote Originally Posted by Angela View Post
    Sounds reasonable. I also think this article is informative:

    http://www.sciencedaily.com/releases...0122091846.htm

    "But in famine conditions, such as when crops fail, they are likely to have eaten all the fermented milk foods, leaving only the more high-lactose products. This would have caused the usual lactose intolerance symptoms such as diarrhea. Diarrhea in in healthy people is not usually life-threatening, but in severely malnourished individuals it certainly can be. So famine could have led to episodes of very strong natural selection favoring lactase persistence."

    In this regard, I find it interesting that recent studies found that the Pontic-Caspian steppe people were nutritionally stressed as children, and that the Finnish population went though an extreme bottleneck. Those sound like famine conditions to me.

    In situations where crops couldn't be grown, or suddenly failed, and people were limited to a more pastoral diet, the ability to digest fresh milk would have been a definite advantage, although it might have taken quite a while to spread widely in a population. This would explain why the herders on the steppe had such deficits in nutrition in childhood. It also would have taken time to figure out how to keep the animals lactating all year long.

    I think people also forget that it's taken thousands of years to reach current levels even in northern Europe. While in Germany about 70% of the people in one area carried it by 1200 AD, in neighboring Hungary in 1000 AD, the figure was only 33%.

    I think this study on it is pretty good, as it's pretty recent, and provides a nice summary of the literature.
    http://www.plosone.org/article/info%...l.pone.0086251

    "The culture-historical hypothesis posits that the LP allele arose from low frequency through selection in cultures with a long history of dairying. By contrast, the reverse-cause hypothesis holds that the LP allele may have already been common in certain populations due to genetic drift and only these populations would have adopted the cultural practice of dairying. Additional genetic pressures may have existed in arid climates where milk is one of the only clean sources of water [27] or in northern latitudes where, in the absence of vitamin D, the presence of lactose facilitates the absorption of calcium by the intestinal mucosa and thus reduces the risk of rickets and osteomalacia [28]. Rickets and osteomalacia can cause deformation of the pelvis and are leading causes of obstructed labor and consequent maternal mortality and perinatal morbidity in traditional societies without access to modern medical care [29]."

    Ed. Given it's distribution, and the fact that it was found in the Basque Neolithic samples, I think there's a question whether it expanded from the Steppe or from Iberia, perhaps with mtDna "H"? That's why it would be interesting to get access to more of the data from the study in the OP.
    Yes, that's how I imagine it.

    Given that initially most people would have got sick from drinking raw milk thus making the situation worse then famine (or hunger generally) strikes me as the most likely driver for people (kids maybe?) deciding to drink it anyway and so the regions around the edge of the farming zone having domesticated animals but relatively poor crop yields would seem the most likely places for this to arise which points towards the zone around the northern and western edges of the LBK zone.


    I think people also forget that it's taken thousands of years to reach current levels even in northern Europe. While in Germany about 70% of the people in one area carried it by 1200 AD, in neighboring Hungary in 1000 AD, the figure was only 33%.
    If the primary benefit was proportional to lack of alternative calories then I'd imagine the percentage (in the most effected areas) could have got very high very quickly during the metal ages and then mostly stabilized over time as farming improved with better seeds, technology (heavy plow) etc.

    If so I wouldn't be surprised if there were ancient populations around the northern and western rim who were almost 100% LP with the percentage declining rapidly south-east - but even if that was the case then yes apart from those regions a slow process.

    (A few of those rim populations might even be less LP than they were in ancient times.)


    I think there's a question whether it expanded from the Steppe or from Iberia, perhaps with mtDna "H"?
    If it was an uncommon random mutation which spread dramatically because it made a life or death difference in particular regions during a particular time period I'd have thought it was extremely likely to be connected to the particular Haplogroup(s) of the person(s) who developed the mutation.

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