A new open-access paper on Italian genetics, Population structure of modern-day Italians reveals patterns of ancient and archaic ancestries in Southern Europe:
European populations display low genetic differentiation as the result of long-term blending of their ancient founding ancestries. However, it is unclear how the combination of ancient ancestries related to early foragers, Neolithic farmers, and Bronze Age nomadic pastoralists can explain the distribution of genetic variation across Europe. Populations in natural crossroads like the Italian peninsula are expected to recapitulate the continental diversity, but have been systematically understudied. Here, we characterize the ancestry profiles of Italian populations using a genome-wide dataset representative of modern and ancient samples from across Italy, Europe, and the rest of the world. Italian genomes capture several ancient signatures, including a non–steppe contribution derived ultimately from the Caucasus. Differences in ancestry composition, as the result of migration and admixture, have generated in Italy the largest degree of population structure detected so far in the continent, as well as shaping the amount of Neanderthal DNA in modern-day populations.
My interpretation of what’s in the paper
– The largest impact on genetic variation across all Italians is “Early European Farmers” who derive from the expansion about of Anatolia. The descendants of Pleistocene hunter-gatherers had a marginal impact and were mostly absorbed.
– A “steppe” component shows a north-south gradient and seems to have arrived in the 3rd millennium. It’s almost absent in Sardinia. It is a minority component, but I believe it brought Indo-European languages to the Italian peninsula.
– Looking at the Tuscan results (more affinity with northern than southern Italy), it seems to me that the genetic impact of West Asians leading to the emergence of Etruscans is now no longer quite so viable. We’ll see. But the demographic impact of the steppe people seems to have been lesser in the Southern European peninsulas than in Northern Europe. Basque survived into the modern period in Spain. Paleo-Sardinian, which persisted into Classical times, was probably not Indo-European. And the ancient languages of Crete seem to have been non-Indo-European. It seems entirely plausible that Etruscan then was a pre-Indo-European survival, though the relationship to Lemnian is still there.
– Southern Italy and Sicily is interesting because of the strong West Asian (“Caucasus”) imprint. A 2017 paper on ancient Mycenaean and Minoan genomes showed evidence of gene-flow from the same area, likely during the Copper or Bronze Age. This could be part of the same migration. Or, it could be part of the legacy of Magna Graecia, the colonization of the region by Greeks during antiquity. Or, it could be due to Roman and later admixtures and migrations.
– The evidence of North African ancestry in Sicily is due probably to the settlements during the two centuries of Islam rule, when Sicily was in many ways part of greater North Africa
https://www.gnxp.com/WordPress/2019/09/04/population-genetic-structure-of-the-italian-peninsula/
