NEW YORK – New research suggests that people living in East-Central Europe between 3,200 and 4,400 years ago, during the Early and Middle Bronze Age, belonged to patrilocal populations with European hunter-gatherer ancestry that participated in collective burials resembling those found in earlier Neolithic populations.
"The demographic history of East-Central Europe after the Neolithic period remains poorly explored, despite this region being on the confluence of various ecological zones and cultural entities," the authors, led by a team at Adam Mickiewicz University in Poland and Uppsala University in Sweden, wrote in Nature Communications on Tuesday, noting that the region has been linked to "a mosaic of genetically distinct populations associated with a variety of cultural entities."
Past research has provided a look at the general population dynamics in Europe over time, the authors noted, revealing hunter-gatherer migrations and ties to different parts of the continent, along with the spread of Neolithic farming populations and subsequent migrations by pastoralist populations originating in the Pontic-Caspian steppe region.
In an effort to tease out the population interactions and dynamics that accompanied archaeological and cultural shifts in the region during the Bronze Age — from changes to pottery patterns and technology to the presence of specific burial traditions — researchers in Poland, Sweden, the UK, and elsewhere performed genetic analyses on dozens of individuals from sites in southern and southeastern Poland, as well as western Ukraine.
Starting with tooth or temporal bone samples from 176 Bronze Age individuals, the team focused in on samples from 91 people for targeted capture enrichment sequencing, generating genetic profiles that encompassed some 15,000 SNPs across the genome.
While the Early Bronze Age populations appeared to genetically resemble the Bell Beaker and Corded Ware cultures that came before them, the team explained, their sequence data pointed to a genetic shift that was evident by the Middle Bronze Age.
Together with a return to large collective burials resembling those found in the Neolithic, for example, the Middle Bronze Age was marked by populations showing an influx of new European hunter-gatherer ancestry.
"What we observe is an additional admixture resulting in the increase of hunter-gatherer ancestry," co-first and co-corresponding author Maciej Chyleński, a human biology and evolution researcher at Adam Mickiewicz University, said in an email.
This population mixing involved an unknown group that appeared to be ancestral to Neolithic farmers, as well as Early Bronze Age populations with genetic profiles that were more similar to those found in Northeastern Europe than to the Early Bronze Age groups identified in East-Central Europe.
Given the type of Early Bronze Age ancestry identified, the investigators suspect that the admixture may have occurred at a more northerly location in Eastern Europe, Chyleński explained, though larger studies spanning a wider site of populations will be needed to explore that possibility.
Based on these and other results, the authors suggested that "hunter-gatherers and farmers remained genetically distinct in some regions," despite an earlier influx of steppe ancestry.
"The results presented here indicate that [Early Bronze Age] people in East-Central Europe … were most likely the direct descendants of preceding populations associated with the [Corded Ware Culture]," the authors reported.
In contrast, they explained, the available genetic and archaeological data suggested that the Middle Bronze Age sites profiled in East-Central Europe "were dominated by patrilocal lineages of apparent hunter-gatherer origin, practicing burial customs that, while displaying some elements associated with steppe pastoralists, were most analogous to those practiced in the Middle and Late Neolithic cultures, predating the arrival of steppe pastoralists into Central Europe."