Gene Expression

Recent Human Evolution in the house

Early man ‘couldn’t stomach milk’

Working with scientists from Mainz University in Germany, the UCL team looked for the gene that produces the lactase enzyme in Neolithic skeletons dating between 5480BC and 5000BC.

These are believed to be from some of the earliest farming communities in Europe.

The lactase gene was absent from the DNA extracted from these skeletons, suggesting that these early Europeans would not be tolerant to milk.

The paper will be Absence of the Lactase-Persistence associated allele in early Neolithic Europeans in PNAS. First LCT, then OCA2, and god knows what else? There is a limit in terms of what you can do with archeoDNA, but if the action went down in the last 10,000 years then it isn’t such a sweat.

One thing, the summary in Science is weird. Check it:

The culture-historical hypothesis is that, shortly after the domestication of livestock, a few lucky farmers with a genetic anomaly hit white gold: nourishment via milk. Then, according to this theory, natural selection took over and these lactase-persistent folks proceeded to populate much of Europe with their milk-guzzling offspring. A competing hypothesis argues that ancient Europeans domesticated milk-bearing livestock because lactase persistence was already quite common in certain populations.

Quite common? The area of the genome around LCT was hit by a hammer blow of selection less than 10,000 years ago, that’s why researchers use it to check if their methods for detecting selection are working. The fact that independent events of lactase persistence exist among other populations via alternative genetic architectures seems to indicate clearly the power of gene-culture coevolution. What’s up with Science doing a “look at both sides” framework when the evidence is so lopsided? I suppose selection could have been induced by a causative factor aside from milk, but I think we’re verging into Humean skepticism at this point, denying the ability to discern causality at all….

Carl Zimmer has much more….

Related: Lactose tolerance by a different stroke. Lactose tolerance/intolerance. Are multiple lactose tolerance mutations surprising? Genes & culture & milk. Lactose tolerance, is it “dominant”? Milk digestion, it does a body good.

Comments

  1. #1 Robert P.
    February 27, 2007

    Having not followed this, I’m a little unclear what you mean by:

    Quite common? The area of the genome around LCT was hit by a hammer blow of selection less than 10,000 years ago, that’s why researchers use it to check if their methods for detecting selection are working. The fact that independent events of lactase persistence exist among other populations via alternative genetic architectures seems to indicate clearly the power of gene-culture coevolution.

    How does the presence of lactase persistence in some subsets of humans argue for one idea over the other? Just curious.

    The nature link isn’t working right now, BTW, might be their site.

  2. #2 razib
    February 27, 2007

    How does the presence of lactase persistence in some subsets of humans argue for one idea over the other? Just curious.

    these data suggest that lactase persistence post-dates domestication of cattle. other data from africa and the levant suggest alternative alleles, and, from what i recall the signatures of selection are more recent in keeping with more recent domestication. the LCT locus shows the strongest signature of selection within the last 10,000 years, for the second hypothesis to be correct (cattle herding was adopted after the fixation of LCT) then there had to be another selective factor. parsimoniously it seems thta the most plausible explanation is for a phenomenon which we have physiological evidence (also, as i said, cattle herding seems to pre-date the fixation of LCT).

  3. #3 J-Dog
    February 27, 2007

    So Fred and Wilma couldn’t order a shake to go with their Brontosaurus, I mean Apatosaurus steak, but a coke, pepsi or a phosphate was okay?

    Just kidding. I am of Irish descent, and we only drank whiskey anyway.

  4. #4 David Boxenhorn
    February 28, 2007

    So are cats lactose tolerant? If so, is it ancestral?

  5. #5 razib
    February 28, 2007

    So are cats lactose tolerant? If so, is it ancestral?

    they aren’t. they like milk, but it gives them upset stomach i think….

  6. #6 Alan Kellogg
    February 28, 2007

    Might the lactose tolerance have been imparted to people from cows via viral gene transfer?

  7. #7 razib
    February 28, 2007

    Might the lactose tolerance have been imparted to people from cows via viral gene transfer?

    adult cows aren’t lactose tolerant from what i know.

  8. #8 Robert P.
    February 28, 2007

    I’ve been thinking about this, and I’m wondering if we’re putting the teat before the meat….actually I just deleted a long post because I realized after thinking it out on my feet, or fingers as the case might be, I understand your point better – and AGREE!

  9. #9 Alan Kellogg
    March 1, 2007

    Razib,

    We may have found a doctorate topic for some grad student to pursue. Are cows lactose tolerant? :)

  10. #10 John
    March 1, 2007

    This is getting very weird. I’m sitting here among 1.3 billion Chinese people. I know a lot of Chinese people. Lots and lots. I don’t know all 1.3 billion of them, but I know a lot.

    A subset have a real problem if they drink a glass of milk – pretty badly upset stomach. A lot of others do not and they consume a lot of cows’ milk.

    A lot of those who are upset by drinking milk have no problem with icecream and various other processed dairy foods. In my experience very few can consume no dairy products at all.

    Anyone who publishes data that say that close to 100% of Chinese people are lactose intolerant is either incompetent, a liar, or they mean “lactose intolerant to some degree” where the degree can be so mild that it does not produce any adverse physical symptoms at all, in which case they really should qualify their statements.

    When is a problem not a problem? Or should I ask why do some people represent something as a problem when it is not a problem?

    I’m not accusing razib, he has posted heaps of references that suggest that lactose intolerance is very variable. But some of the published data are, on the face of it, just unqualified rubbish.

  11. #11 Ed Harrison
    March 2, 2007

    We may have found a doctorate topic for some grad student to pursue. Are cows lactose tolerant? :)

    I am a cattle rancher, maybe you should ask if it gives them a belly ache? I have noticed that calves will nurse well into adulthood given the chance. I suggest a government grant there.

  12. #12 kat
    March 9, 2007

    Wait, so they didn’t find the gene for lactase at all in the populations from 5000 BC? That doesn’t make sense, since the issue in lactose tolerance vs. intolerance isn’t the presence of the gene that encodes the enzyme, but the persistent expression thereof into adulthood. So the gene ought to be present in all human populations… it’s just whether or not it’s expressed that’s variable. Unless of course they’ve found the particular transcription factor or other factor with the polymorphism that dictates lactase persistence vs. downregulation? It sounds to me (disclaimer: haven’t read the article) that they may just have not sequenced the right chunk of DNA to find the gene.

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