A new paper on Italian Bronze Age and Iron Age genomics, Ancient genomes reveal structural shifts after the arrival of Steppe-related ancestry in the Italian Peninsula. The abstract:
Across Europe, the genetics of the Chalcolithic/Bronze Age transition is increasingly characterized in terms of an influx of Steppe-related ancestry. The effect of this major shift on the genetic structure of populations in the Italian Peninsula remains underexplored. Here, genome-wide shotgun data for 22 individuals from commingled cave and single burials in Northeastern and Central Italy dated between 3200 and 1500 BCE provide the first genomic characterization of Bronze Age individuals (n = 8; 0.001-1.2× coverage) from the central Italian Peninsula, filling a gap in the literature between 1950 and 1500 BCE. Our study confirms a diversity of ancestry components during the Chalcolithic and the arrival of Steppe-related ancestry in the central Italian Peninsula as early as 1600 BCE, with this ancestry component increasing through time. We detect close patrilineal kinship in the burial patterns of Chalcolithic commingled cave burials and a shift away from this in the Bronze Age (2200-900 BCE) along with lowered runs of homozygosity, which may reflect larger changes in population structure. Finally, we find no evidence that the arrival of Steppe-related ancestry in Central Italy directly led to changes in frequency of 115 phenotypes present in the dataset, rather that the post-Roman Imperial period had a stronger influence, particularly on the frequency of variants associated with protection against Hansen’s disease (leprosy). Our study provides a closer look at local dynamics of demography and phenotypic shifts as they occurred as part of a broader phenomenon of widespread admixture during the Chalcolithic/Bronze Age transition.
The samples pick up steppe ancestry around 1600 BC, but that’s due to a lacuna in the transect. We know now that steppe ancestry arrived in Spain and Greece before 2000 BC. It seems to me unlikely that it would be notably tardy in Italy.
Another thing I want to mention is there is clearly something West Asian (CGH-related) that is moving westward ~2000 BC in a straight shot from Anatolia to the Balkans to southern Italy. This migration seems associated with Y chromosomal lineage J2. Trying to estimate how much exogenous post-Imperial eastern ancestry is present in Southern Italians is somewhat difficult for this reason. The differences between the far south and central and northern Italy may date to the Bronze Age because of this minority component of West Asian ancestry that extended itself across the Mediterranean.