August 20, 2012
Visualizing admixture differences with ACD tool
Vaêdhya has created a new ACD tool that allows one to visualize differences between sets of populations in terms of admixture components. He also posts two examples of the application of his tool on data generated by myself in the Dodecad Project, as well as by the Harappa Project.
I have speculated about the origins of Indo-Iranians before, noting that the evidence links even the Kurds with a "South Asian" component; in subsequent higher-resolution analysis, such as the K12b, it appeared that this component was related to the Gedrosia component. In any case, the evidence is clear about the links of different Iranian and Indo-Aryan groups, so it is nice that this can be made evident with the ACD tool and data from the Harappa Project. Notice the excess of the Baloch (~Gedrosia) component in Kurds and Iranians in contradistinction to the Indo-European Armenians and Semitic Assyrians. It is fairly clear to me that the Iranian ancestral homeland is to be sought to the east, with the Bactria-Margiana Archaeological Complex (BMAC) being a good candidate for its location.
In a second plot, Vaêdhya uses Dodecad data to contrast patterns of differences in Northeastern Europe. Here, too, the patterns are clear, with Finns, and secondarily Russians showing an excess of Siberian ancestry relative to Poles. This is, no doubt, due to the Finnic element, which links Finns, and the Uralic substratum in Russians with Siberia. A second contrast is between Finns and Russians/Poles. The latter have more of the Caucasus component, a probable legacy of the Bronze Age Indo-European invasion of Europe. A final contrast is the higher Atlantic_Med element in Poles, which suggests an excess of early Neolithic farmer ancestry, or, admixture with West European populations such as Germans and others who possess more of this component than Slavs.
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4 comments:
The "Caucasus" in Poles and Russians is Neolithic ancestry via the Balkans.
It probably also includes Bronze Age admixtures from non-Indo European groups that settled in Southeastern Europe.
You can see the cline between Poland and the Balkans produced by these admixtures on any half decent PCA/MDS plots. But there's never any cline between Poland and the Caucasus.
The South Central Asian admixture in Kurds and Iranians makes sense too, and it arrived in West Asia with R-Z93, and with North European admixture, from the east.
R1a1a expanded from the Volga delta region into Asia. Most of that was R-Z93, but probably also some R-Z283. It then moved around the Caspian Sea into Central and South Central Asia, along with North European autosomal admix, and then finally into West Asia.
Everything is becoming clear thanks to a better understanding of R1a, which certainly comes from Neolithic West Asia, but expanded in number and diversity in Central Europe during the late Neolithic/Copper Age.
"The latter have more of the Caucasus component, a probable legacy of the Bronze Age Indo-European invasion of Europe."
There's hardly a need to explain this apart from geography.
You can see the cline between Poland and the Balkans produced by these admixtures on any half decent PCA/MDS plots. But there's never any cline between Poland and the Caucasus.
There is no reason to be a cline between Poland and the Caucasus. The eastern European plain, has seen the comings and goings of many different groups, of Iranic, Uralic, Turkic, and Slavic origin. The current discontinuity between it and the Caucasus largely reflects the eastward settlement of eastern Slavs during the medieval period and has no relevance for prehistory.
Also, it's not clear how Indo-Europeans entered northern Europe. There are three options on the table: from the Balkans, across the Caucasus or from the trans-Caspian steppe.
We will know more about the timing and routes of the spread of the IEs as more aDNA becomes available.
The assertion , 'in contradiction to armenian and semetic assyrian' is weak.
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