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.