The population genetic structure of Sicily and Greece

By total coincidence a paper came out yesterday, Ancient and recent admixture layers in Sicily and Southern Italy trace multiple migration routes along the Mediterranean (I blogged about the topic). It’s open access, and it has a lot of statistics and analyses. I’d recommend you read it yourself.

You see the Sicilian and Greek populations and their skew toward the eastern Mediterranean. But in the supplements they displayed some fineSTRUCTURE clustering, and at K = 3 you see that Europe and the Middle East diverge into three populations. What this is showing seems to be: 1) in red, those groups least impacted by post-Neolithic migration 2) in blue, Middle Eastern groups characterized by the fusion between western & eastern Middle Eastern farmer which occurred after the movement west of the ancestors of the “Early European Farmers” (who gave rise to the red cluster), who were related to the western Middle Eastern farmers 3) the groups most impacted by Pontic steppe migration.

The authors confirm what I reported over two years ago on this blog: mainland and island Greeks are genetically distinct, probably because the former have recent admixture from Slavs and Slav-influenced people. And, many Southern Italians resemble island Greeks.

One has to be careful about dates inferred from genetic patterns. For example:

Significant admixture events successfully dated by ALDER reveal that all Southern Italian and Balkan groups received contributions from populations bearing a Continental European ancestry between 3.0 and 1.5 kya

The beginning of folk wanderings in the Balkans which reshaped its ethnographic landscape really dates to the later 6th century, when the proto-Byzantines began to divert all its resources to the eastern front with Persia, and abandoned the hinterlands beyond the Mediterranean coast in Europe to shift its focus toward the Anatolian core of the empire. The Slavic migrations were such that there were tribes resident in the area of Sparta in the early medieval period. Presumably because they were not a seafaring folk they don’t seem to have had much impact on the islands.

Such an early period in the interval though can not be the Slavs. What can it be? I suspect that that there are signals of Indo-European migrations in there that are being conflated due to low power to detect them since they are rather modest in demographic impact. The islands such as Sardinia, Crete and Cyprus had non-Indo-European speakers down to the Classical period.

Overall it’s an interesting paper. But it needs a deeper dig than I have time right now.


9 thoughts on “The population genetic structure of Sicily and Greece

  1. Before 1923 (when the population exchange happened) there were lots of Greeks living along the Black Sea (in what’s now Bulgaria, Romania, Turkey, etc) even as far as the Caucasus. The exchange was significant: ~20% increase in population. Any way of telling how much of the Slav influence comes from the Pontic Greeks?

  2. why would u assume they’d have much slavic influence? there isn’t that much in the armenians or turks sampled, except for recent admixture. i’m aware that byzantines and ottomans engaged in some resettlement, but not enough to make a difference.

  3. iirc, Pontic Greeks and Pontic Turks alike are unique among their meta-ethnic groups for being very genetically similar to Armenians and Georgians—and particularly low in European and Turkic ancestries, respectively.

  4. My neighbor Nick’s family hailed from Sparta. He is tall with light hair and light eyes. Unlike my doctor whose family came from Thessaloniki. He is short, with dark hair and dark eyes.

    Note to annon. 1:13 pm Thessaloniki was a major resettlement destination for Greeks expelled from Turkey.

  5. “The authors confirm what I reported over two years ago on this blog: mainland and island Greeks are genetically distinct, probably because the former have recent admixture from Slavs and Slav-influenced people. And, many Southern Italians resemble island Greeks.”

    Interesting post, but your prediction is wrong since mainland and island Greeks are distinct primarily due to genetic drift caused by geography rather than admixture from Slavic/Slavicized tribes. In other words, the hypothesis made by Sarno et al. regarding continental Greeks is falsified by the genetic studies below confirming the historical fact that Slavic/Slavicized admixture in the majority Greek population (continental or otherwise) was and still remains negligible.

    *Stamatoyannopoulos et al., Genetics of the Peloponnesean Populations and the Theory of Extinction of the Medieval Peloponnesean Greeks, European Journal of Human Genetics advance online publication 8 March 2017; doi: 10.1038/ejhg.2017.18

    *Kushniarevich A, Utevska O, Chuhryaeva M, Agdzhoyan A, Dibirova K, Uktveryte I, et al. (2015) Genetic Heritage of the Balto-Slavic Speaking Populations: A Synthesis of Autosomal, Mitochondrial and Y-Chromosomal Data. PLoS ONE 10(9): e0135820

    Although the Sarno et al. study is interesting, it fails to incorporate the findings of both Kushniarevich et al. and Stamatoyannopoulos et al. and rests its historically dubious hypothesis regarding continental Greeks heavily on a limited number of Greek continental samples.


  6. perhaps that is true of peloponnesian greeks .doesn’t mean it was different in salonika. will read papers more closely later.

    p.s. i doubt it is drift. though will check homozygosity in the samples later too.


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