Copping a Latitude: Genetics Supports Idea Cultural Interaction Was More East to West Than North to South

Charles Q. Choi, Scientific American, September 26, 2011

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For decades scientists have suggested that the east-west orientation of Eurasia helped spread ancient culture and technological innovations such as agriculture and writing more rapidly than occurred in the oppositely oriented Americas, with biologist and ecologist Jared Diamond perhaps most famously making this case in his Pulitzer Prize–winning Gun, Germs and Steel: The Fates of Human Societies (W. W. Norton & Co., 1999). The idea is that populations at comparable latitudes experience largely similar climates, making it easier to adapt crops and domesticated animals and, consequently, humans and technology to new locations east to west. On the other hand, migrating across lines of latitude, north to south, involves adapting to new climates.

Given this notion, genetic analysis might reveal greater differences among human populations north to south than east to west within continents, says population geneticist Sohini Ramachandran at Brown University. If migration is harder across lines of latitude than longitude, then populations would be more isolated north to south, giving them more chances to diversify compared with one another.

To see if this was the case, Ramachandran and her colleague Noah Rosenberg at Stanford University analyzed genetic variation data in 678 genetic markers from 68 populations. This included data from 39 populations from Eurasia–including Europe, southern and central Asia, and the Middle East–collected from the Human Genome Diversity Cell Line Panel, along with 29 populations from Native American groups, such as the Cree, Ojibwa, Maya and Zapotec, gathered by former collaborators of the researchers. “Only recently did we have the kind of genetic data to perform this kind of comparative analysis of Native American and Old World populations,” Ramachandran says.

{snip} They discovered more genetic differences north to south in the Americas than over comparable distances east to west in Eurasia, findings detailed online September 13 in the American Journal of Physical Anthropology.

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In the Americas distance north to south explained a good deal of genetic variation. Distance east to west did so as well, although to a lesser extent. This is probably due to the diagonal northwest-southeast positions that North and South America have in relation to each other, respectively.

One potential caveat regarding these findings is that culture and technology could spread from one population to another without them otherwise intermingling and sharing genes, Ramachandran says. As such, although they found evidence that changes in latitude could impede genetic flow, it might not necessarily impair cultural or technological flow.

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[Editor’s Note: View the study here.]

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  • anonymous

    Makes perfect sense.

    Migrating North-South only a few degrees of latitude brings major changes in climate.

  • Anonymous

    This sort of shoots a hole in Senator Biden’s comment to Hispanics and their constant claim to lands they obviously never adapted to. Actually, it is quite evident that very little migration after the initial Asian bridge migration, especially back to the north, ever occurred.

  • neanderthalDNA

    Good stuff. I wonder if this North South genetic isolation could explain some early North Americans’ observation that many Amerindians looked more European than others?

  • margaret

    This makes sense, especially the asia european movements. But, this is Jared Diamond Brown and Stanford universities’ liberal arts departments.

    I’ve read 2 of Diamond’s books. All I remember is that they were total nonsense. Brown and Stanford are American Univeristies by definition part of the anti White racist anti western civilization anti American propagada machine.

    This could be true, but it comes from 2 American universities.

    I believe nothing but hard science out of American universities, colleges and the federal and state departments of education.

    They lie about everything else. Their record makes all their studies and research suspect.

  • Anonymous

    I thought everybody knew this;

    Is there one smart or successful (indigenous) society south of the equator?

  • Anonymous

    It makes sense. One could travel from the north of Spain on the Atlantic coast all the way across to the Pacific coast of Russia and see largely the same types of scenery – grasses and trees. There would be some variations but the overall flora and fauna would be the same. That same trip southward across the straits of Gibraltar would soon see you run into the blazing heat of the Sahara with its endless sand dunes, then the Sahel and into the jungles of the African continent. Totally different climates and sceneries in a much smaller distance.

  • Dennis

    Diamond’s thesis has always made sense–but its proponents seem blissfully unaware of its implications. That is, if geography determines the extent of a given society’s advancement it must also, over tens of thousands of years, genetically mold its population, behaviorally as well as physically.

    I suspect S.J. Gould’s “punctuated equilibrium” theory was motivated largely to perpetuate the article of faith at the center of his hogwash: that evolution “stopped” when we became civilized because we were no longer cowering beneath the elements and running from predators. For this to be true one has to presume a population uniform in personality and intelligence, or where everyone has the same amount of offspring, enduring for years without famine or genocide intruding.

  • Fr. John+

    On White Racialist websites, there has been a large discussion as of late, about the non-adaptability of Caucasoids south of the 34th parallel, and how this was the main reason that sub-saharan slaves (blacks) were more ‘fitted’ to live in those climates.

    The ‘fire and ice’ visage of blond/blue-eyed people has a corresponding geographical reality, it would appear.

  • Anonymous

    “On White Racialist websites, there has been a large discussion as of late, about the non-adaptability of Caucasoids south of the 34th parallel, and how this was the main reason that sub-saharan slaves (blacks) were more ‘fitted’ to live in those climates.”

    That’s intersting. But then why have the European settlers of S. Africa build such a successful society when the bushmen and hottentots were still living in the stone age when the Portuaguese first arrived? Caucasion Whites both English, Indians and Persians have done well in India.