German Dziebel’s Guest Blogging

3 Responses

1. 

   Alvah Hicks March 19, 2012 at 7:45 pm · Reply →

   Great site German

2. 

   tt9j August 20, 2012 at 3:02 am · Reply →

   Dear German Dziebel;
   What do you think about the following comments from:
   http://bga101.blogspot.com/2012/08/admixture-and-structure-tests-arent.html

   Now … it seems as if Europeans mostly carry the type of East Asian ancestry that was present in the first human migration wave from Asia to the New World, which moved across the Bering Strait about 15,000 years ago.

   So, did a migration wave from the same source also move into Europe at about the same time? If so, this would indicate that the East Asian admixture in Europeans found by David Reich is very old. Perhaps that’s why it’s not possible to measure it accurately using standard ancestry tools?

   1. 

      German Dziebel August 20, 2012 at 4:04 pm · Reply →

      I remember this somewhat enigmatic quote from Reich and I referenced it myself at http://anthropogenesis.kinshipstudies.org/2012/07/a-three-wave-model-for-the-peopling-of-the-americas-or-a-three-wave-back-migration-from-the-americas-to-the-old-world/

      Am glad that Davidski pick up on it, too.

      Admixture-kind of analyses (both academic and amateurish) have long detected the puzzling Amerindian component found at low to moderate frequencies across northern Eurasia.
      http://anthropogenesis.kinshipstudies.org/2012/03/admixture-an-amerindian-component-in-eurasian-populations-3/. I think what Reich is referring to is the same genetic phenomenon. He just calls it “East Asian,” which is misleading.

      If we look at mtDNA, it’s becoming increasingly clear that pre-Neolithic populations in Europe tend to belong to hg U (with highest frequencies in Saami, among modern human populations). Hg U is part of mhg R, which has a East Asian/Southeast Asian/Amerindian distribution. So, even at the root of modern European mtDNA phylogeny we find “East Asian” affinities. Paleolithic DNA studies will tell us whether hg U hits the very bottom of European mtDNA variation, or there was a pre-U substrate that got lost in subsequent populations.

      Paleobiologists argued that, from the point of view of skulls, Amerindians must have diverged prior to the separation of Caucasoid and Mongoloids. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.21425/abstract. In the light of the genetic evidence, this can be re-interpreted as the possibility that Caucasoid and Mongoloid skull variation is a subset of Paleoamerican skull variation. Anthropologist Peter Brown noticed that typical Mongoloid skulls appear in the New World before they appear in Asia and proposed that the formation of the Mongoloid type in Asia can be attributed to a back-migration from the New World (at the end of the last Ice Age).

      Piecing all of this together, it’s possible that what we are seeing here is evidence of a back-migration from the Americas to the Old World in the past 10-15,000 years of a population that’s responsible for an important piece of East and West Eurasian genetic and phenotypic profile.

      It’s less parsimonious to hypothesize a perfectly timed concomitant migration of a very atypical Asian population from the very same place in East Asia to a) Europe b) New World. It’s wiser to consider that we have underestimated New World as a source of Old World variation. Linguistically speaking, America harbors 2/3 of world linguistic diversity as measured by the number of unique stocks. Hence, linguistically, it’s easy to see not just nothern Eurasia but all of the Old World as a subset of New Word variation.