Genes & geography – the great correlation

By Razib Khan | August 25, 2012 12:06 am

A paper is out in PLoS Genetics which attempts to formalize the relationship between genes and geography, A Quantitative Comparison of the Similarity between Genes and Geography in Worldwide Human Populations. They found a reasonable correlation, but there are two issues. First, African hunter-gatherers tend to reduce the correlation. This makes sense. If you think of African genetic variation to a great extent being shaped by the wave front of Bantu expansion, then isolation by distance works well enough. But the Pygmies, Hadza, etc., are isolated shoals which disrupt the smoothness of the sea of Bantu genetic variation. Second, they found a really good correlation in Asia. But one should be cautious about this:

However, although the concordance of a PCA plot with geography is perhaps best known for Europe — which does not have a barrier of comparable importance to the Himalayas — we obtained the unexpected result that in spite of the Himalaya barrier, the Procrustes similarity score was actually highest in Asia. When further examining the population structure on separate sides of the Himalayas, we found lower similarity scores between genes and geography in our East Asian and Central/South Asian samples. Especially for the East Asian sample, our results indicate weaker correlation between genes and geography in the east-west direction.

CATEGORIZED UNDER: Anthroplogy, Genetics, Genomics
MORE ABOUT: Human Genetics
  • NickMatzke

    “Especially for the East Asian sample, our results indicate weaker correlation between genes and geography in the east-west direction.”

    That’s a little confusing if the Himalayas are supposed to be a barrier between North and South.

    But regardless, you can see the “hole” in the continuity caused by the Himalayas right there in the graphic I think. Continuous around the edges but not directly across.

  • https://plus.google.com/109962494182694679780/posts Razib Khan

    But regardless, you can see the “hole” in the continuity caused by the Himalayas right there in the graphic I think. Continuous around the edges but not directly across.

    i went to a talk by noah on this. he stated that yes, the mountain range has a much larger change in genetic distance than other regions. don’t know if that’s in the suppelementals.

  • Dm

    Posting here simply because it is a recent open post mentioning Hadza. If there is a need to move it to a different, better suited topic, please let me know!

    So NYT says that Hadza don’t consume more energy than the Westerners do, despite their arduous gathering and hunting activities.
    http://www.nytimes.com/2012/08/26/opinion/sunday/debunking-the-hunter-gatherer-workout.html?hpw&gwh=5CC08ED27003B1582B4F836D6F822A02
    They hypothesize that the Hadza save energy on unspecified activities other than walking and carrying loads. (Presumably digestion also is taking more energy for them?). Should we hypothesize that they spend less energy thinking? Any other good venues for energy efficiency?

    BTW the paper starts out from stating that we “evolve as hunters and gatherers”, and IMVHO this statement requires a lot of qualifiers. For too much evolution happened after switch to agriculture to leave it unqualified, what do you think?

  • http://twitter.com/allenday Allen Day

    keep it up, so great to have you surfacing this stuff from the literature.

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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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