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September 20, 2004

Norden & southron

In response to the data about male mediated demic diffusion in China along a north-south gradient Steve wonders why this seems a recurring pattern-that is, northern males with southern women.

1) I don't know how robust this pattern is (think Europe's possible J haplogroup Neolithic diffusion from Anatolia).

2) I think this is easily explained as a function of geography. There is just more land in the northern regions of Eurasia. For example, if you look at India, the tapering off of the landmass to the south and the fact that it is surrounded by water suggests that new peoples will have to come from the north, likely the northwest because of the topography. The peoples from the north will have exposure to new technologies and likely be subject to greater competition. An analogy might be the periodic extinctions that would buffet North America whenever Beringia bridged the gap between Old World and New (and on a smaller scale when the Isthmus of Panama connected North to South America and the smaller continent experienced die off as northern species invaded).

This can be examined in light of the southern hemisphere. If this was a climate induced fact one would expect the arrow of migration/domination to flip.

  • In Africa the Bantu expansion began in the region of eastern Nigeria and swept east and south until the Khoisan people who dominated the southern half of the continent were caged within the deserts of the Kalahari and Namib and on the non-tropical Cape.
  • Australia seems to have been subject to several migrations, all from the north, via the tropical zone toward the south (the last major one brought the dingo about 8000 years ago).
  • There is some conjecture that the peoples of southern Patagonia were relicts of a population that was swamped by the waves out of Beringia

True, this is a north-south migration, but it is a tropical to temperate movement, instead of the reverse. The variable that has remained constant is the size of landmass from which the more dominant group originates from. Here is a case where the temperate zones are less extensive, and the peoples who inhabit them are more prone to be overwhelmed by tropical peoples with more well developed information networks because of geography.

Posted by razib at 05:20 PM