Daily Data Dump – Thursday

By Razib Khan | August 19, 2010 5:06 pm

Which population is most genetically distant from Africans?. Dienekes argues that Amerindians are the furthest not due to bottlenecks, but because of isolation from gene flow. He points to particular markers which span Africa and Eurasia. I know of the one he’s talking about. I need to rethink whether the first approximation of no major gene flow since Out-of-Africa (OoA) except for recent historical migration is useful, mostly because I haven’t familiarized myself with the literature well enough.

Inferring Geographic Coordinates of Origin for Europeans Using Small Panels of Ancestry Informative Markers. 500-1000 well selected SNPs are sufficient to narrow down geographical origin of an individual within Europe. I assume that the number would be lower in Africa.

The effect of ancient population bottlenecks on human phenotypic variation. Doing with skulls what you do with genes. Same general results.


Time to revise the mtDNA timescale? What’s a few tens of thousands of years? Well, it matters quite a bit since you need to align genetic with paleoanthropological data. Conflicts between geneticists and anthropologists and paleontologists have been flaring up since the 1960s. Sometimes the geneticists are right, as Allan Wilson was about the separation between humans and other primates, and sometimes the geneticists are crazy, as Wilson was when some wrong results in his lab indicates that modern humans had their origin in Australia (see The Monkey Puzzle, where the authors report this bizarre preliminary result in the conclusion to tantalize the readers. The source was Allan Wilson, and it was just crazy on the face of it).

People With No Religious Affiliation Have Less Favorable Views of the US. Being irreligious makes you unpatriotic, but being an ethnic minority does not. This may not be generalizable across nations, I looked at China in The World Values Survey and religion (or lack of) doesn’t make a difference.

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  • dan

    i have link from NPR to contribute if it’s ok:
    http://www.npr.org/templates/story/story.php?storyId=129155123
    it’s about the evolution of language from the NPR Human Edge series

  • toto

    Dienekes argues that Amerindians are the furthest not due to bottlenecks, but because of isolation from gene flow. He points to particular markers which span Africa and Eurasia.

    That’s only an argument if the marker in question post-dates the original migration (I checked – apparently it does).

  • bioIgnoramus

    I once received a short tutorial on the geographic origins of Europeans in the great scientific city of Cambridge. I’d gone into a shop to buy a cycling helmet. The Grande Dame presiding told me that the key question was whether my skull had an Italian or French shape. She made me try on various helmets and was able to declare that I was conclusively Italian by origin. I have never in my life been mistaken for Italian, though I once was for French, but that just shows the superiority of science as conducted by a cycling suprema. Anyway, I offer this gratis, as a potential undergraduate research project studying the sales of different cycling helmets across Europe or the USA. Get to it, skull fanciers!

  • Sandgroper

    I just about get that cranial metrics are a function of maximum temperature (not really – I can see how it plays into skull size, but not shape), but I don’t think I understand why they are a function of rainfall. What is the operative factor, cloud cover/solar radiation?

    I’ve searched but can’t find anything specific.

  • chris y

    Dienekes argues that Amerindians are the furthest not due to bottlenecks, but because of isolation from gene flow. He points to particular markers which span Africa and Eurasia.

    Has the gene flow across the Torres Strait been significantly greater than that across the Bering Sea, i.e. tiny but constant? How could this be tested?

  • Matt

    I just about get that cranial metrics are a function of maximum temperature (not really – I can see how it plays into skull size, but not shape), but I don’t think I understand why they are a function of rainfall. What is the operative factor, cloud cover/solar radiation?

    Long slender objects (like small objects) have a high surface area:mass ratio while spherical objects (like large objects) have a low surface area:mass ratio. Assuming there’s either (or both) selection to conserve head heat in cold environments or to shed head heat in warm environments (and relaxed selection or opposing selection in warmer/less warm environments) that could be reflected in skull shape.

    Seems like the evidence shows that selection is only on conserving heat and that there isn’t much selection for skulls in warm climates to shed heat though (see – http://dienekes.blogspot.com/2009/09/climate-influence-on-morphological.html and http://dienekes.blogspot.com/2009/07/drift-more-important-than-selection-in.html ).

    I’d think precipitation would matter in terms of moistening air, which is a factor effecting the shape of the nose, which might have effects on skull shape, since the face and neurocranium are integrated, although I would have thought this would be slight. Also I’m not sure if heat exchange is affected by air moisture, but that also might matter in theory. Humidity apparently decreases ability to lose heat by sweating.

  • Dhruva

    Razib,

    Your one of my favorite bloggers whose a person of color.

    But sometimes I get the feeling you wish you were white? Is this true? Or are you proud to be a person of color?

    Keep up the good work.

  • Sandgroper

    Allegedly frequent trading contacts, but no evidence by way of transfer of culture (Torres Stait islanders were farmers who had bows and arrows, but none of that got transferred to the mainland). There’s some stuff about stone points, but it’s unconvincing to me. I have never understood why cultural innovation can’t happen spontaneously within an isolated population – that had to happen somewhere sometime. We all have our Eureka moments.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    But sometimes I get the feeling you wish you were white? Is this true? Or are you proud to be a person of color?

    don’t care. i obviously hold myself in high regard, but not because of the color of my pelt :-)

  • Chris T

    “Dienekes argues that Amerindians are the furthest not due to bottlenecks, but because of isolation from gene flow.”

    I would have expected this just by looking at a map. They’re the most isolated (barring Australian Aborigines and Pacific Islanders) and therefore have had the most time to drift genetically.

  • Sandgroper

    Thanks Matt. Yes, humidity seems plausible.

  • Marnie

    “From what we can tell there was relatively little gene flow after the initial settlement of the New World and Oceania (actually, there may have been several waves into the New World to be fair, but it looks like there wasn’t enough Eurasian gene flow to dampen the reduction in heterozygosity caused by bottlenecks).”

    There may be a way to test Dienekes’ hypothesis that Amerindian populations are the most genetically distant from Yorubans based on the time they have been isolated from Eurasians and Africans.

    Edward Vadja, working primarily from linguistic data, suggests that there are three separate migrations into the Americas: Amerindian, Na Dene and Eskimo-Aleut, with Ameridians being the first migrators and Eskimo-Aleut being the last. The Fst distance between these groups and the Yoruba should be highest for Amerindians and lower for the Eskimo-Aleut.

    There probably is not a continuum of genetic crossover between Eurasians and Africans, but it would be interesting to see how these Fst numbers correlate with hypothesized dates for Eurasian-African genetic crossovers, if they are known.

    One note of caution: Dienekes’ Fst numbers for Amerindians are taken from a paper on Koreans, with the Amerindians used only as a reference point. The Amerindian sample is comprised only of 16 people.

    In addition to looking at Beringia migrations, it would also be interesting to look at the still in Siberia suspected groups of origin for the Eskimo-Aleut and Na Dene.

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

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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