Monday, November 15, 2010

Assyrians

"Ashur lived at the city of Nineve; and named his subjects Assyrians, who became the most fortunate nation, beyond others” (Antiquities, i, vi, 4): Flavius Josephus


Once again, with the recent Dodecad Ancestry Project results for Assyrians, we see a breathtaking concurrence between history and autosomal genetic data.

Having existed in various entities for so long, it is difficult to easily define Assyrians.  In my definition, I will reference, apologetically, the wiki page for Assyrians, as the hard work of defining the various Assyrian historical periods seems to have been done there.  Wikipedia also has a very good map of the Fertile Crescent during the Middle Assyrian period:



Prior to and during the Early Period (circa 1920 BC – 1840 BC), Assyrians were a people of the upper Tigris River who traded with people of the Anatolian plateau in what would be Wilusa and Assuwa on the above map.  Interestingly, the political structure of ancient Assyrian cities was one where the basis of authority rested with the city through an assembly of elders, a hereditary ruler and an eponym who was annually elected by lot to administer commercial interests. 

In about 1840BC, the city of Ashur was conquered by Shamshi-Adad I, King of the Amorite tribe to the southwest.  During the succeeding centuries of the Middle Assyrian period, the Assyrians allied themselves variously with the rising power of Babylon to the southeast and the Hanigalbats and Hittites to the north.  The above map represents that period.

Significantly, Assyrian trade and relationships with the Anatolian Plateau ceased during the Middle Assyrian period, as Babylonia became the focal point of Assyrian trade relations, rather than Anatolia.

With this history in mind, it is interesting to look at the genetic makeup of Modern Assyrians (2) against a background of Modern Syrians (1):

At first glance, it seems like these are a different people.  Thinking about demic diffusion, you can begin to sort out how Syrians and Assyrians, neighboring inhabitants of the Fertile Crescent, are the same and different.

I revert to the discussion of the simple demic diffusion model proposed for Syrians.  This model suggests that Syrians are comprised of an ancient Fertile Crescent mix of West Asian, Southern European and Southwest Asian components, as described in the Dodecad Ancestry Project.  Syrians also show evidence of the Egyptian occupation of Syria in the 14th century BC.   Likely by way of ancient Babylonia, they show a South Asian component.  The contributions from Egypt and South Asia are at 12% and 6%, respectively.

Assyrians, on the other hand, show very little influence as a result of the Egyptian occupation.  This may be due both to the geographic position of Assyrians on the Upper Tigris River, as opposed to further west, and also due to the religious isolation of Assyrians. Assyrians do show a 2% contribution from South Asians, perhaps indicating a very ancient but low level South Asian presence in Babylonia.

We now plot Assyrians in the "Fertile Crescent" picture, with the results normalized on the West Asian-South European-Southwest Asian components, and with results for Northern Europeans and South Asian components included:


In this picture, both Assyrians (3) and Syrians (5) show the familiar West Asian-Southern European- Southwest Asian mix.  Both present the Southern European component at about 22%.  Both show a small component from South Asia.  In fact, all populations except Egyptians show a small genetic contribution from South Asia.  However, what is most striking about these results is the shift toward the West Asian component for Assyrians compared to Syrians.  It is as if Assyrians, genetically speaking, are frozen in time, sometime in the Middle Assyrian Period:  they have a smaller Babylonian South Asian component (2% vs 6%),  lack the Egyptian component of the 14th century BC Egyptian occupation and have significantly less of the Southwest Asian component (23% vs. 36%) than Syrians. 

In combination with the high Southwest Asian Component results for Saudis, Egyptians and Ethiopians(Dodecad Ancestry Project), this results indicates that the Southwest Asian component has been diffusing northward since the Neolithic.  Moreover, the conquest in 1840BC of the Assyrians by Shamshi-Adad I, King of the Amorites, may have been a significant genetic event, bringing the Southwest Asian genetic component northward.

By comparison, the high West Asian components in Lezgins, Georgians, Modern Turks and Armenians indicates that the origin of the West Asian component is in the Southern Caucasus and has been diffusing southwestward since the Neolithic.

If we assume that Assyrians are a genetic "snapshot" of the Middle Fertile Crescent during the Middle Assyrian Period, we can then begin to guess at a rate for the northward diffusing Southwest Asian component and the southward diffusing West Asian component in this region.  I'll be developing this idea further in subsequent posts.

If this diffusion model is correct, prior to the Bronze age, Assyrians and their predecessors were a "West Asian"/ "South European" people.  That would make early northwestward migrating Assyrians an obvious candidate for a demic transmission of farming to the Western Black Sea and Balkans.

I'd like to thank Dienekes Pontikos and the Dodecad Ancestry Project for collecting and generating the ADMIXTURE results for Assyrians and also thank "handschar" on dna-forums for recommending that I look at the Dodecad Assyrian data.

Update January 24th, 2011: An update on the use of ADMIXTURE for analysing Middle Eastern Populations

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