April 23 (UPI) -- Central Europe was marked by significant population shifts during the end of the Neolithic period, but the timing and details of new migrations and population mixing in the region aren't well understood.
To gain fresh insights into this dynamic period, researchers sequenced 96 ancient genomes recovered from burial sites in Switzerland.
Though ancient burial sites are less abundant in Switzerland than in other parts of Europe, the country is home to a rich archaeological record -- artifacts that offer context to the genomic data scientists were able to recover and study.
By the mid-to-late Neolithic, indigenous settlements were scattered through Central Europe. Local populations settled along lake shores, inside alpine valleys and high atop mountain passes.
By the end of the period, artifacts linked to the Corded Ware Complex cultural groups begin showing up in the archaeological record. The artifacts coincide with the estimated arrival of people migrating westward from the Pontic-Caspian steppe.
The new genomic analysis -- detailed this week in the journal Nature Communications -- suggests the people of the steppe first arrived around 2800 BC.
In addition to pinpointing the timing of the arrival of the earliest steppe migrants, the genomic analysis showed mixing between the indigenous settlers and the steppe migrants was very slow. Researchers found evidence that two parallel and highly genetically structured societies persisted for centuries.
"We see in our data that there was genetic mixing, it only took quite some time until everybody carried the new component," lead study author Anja Furtwängler, a paleogeneticist at the University of Tübingen's Institute for Archeological Sciences in Germany, told UPI in an email.
Furtwängler and her colleagues found evidence that some people remained without the genetic signatures of steppe ancestry for more than 1,000 years after the first migrants arrived. The genomes recovered from the ancient Neolithic burials revealed the earliest known lactose-tolerant Europeans, dating to 2100 BC.
Both the burial and genomic data also showed that the social structure of the Neolithic settlements were predominantly patrilocal, with males staying where they were from, while females came from distant Neolithic, non-steppe populations.
"We could not pinpoint the origin of these women without steppe ancestry," said Furtwängler. "Usually one can conduct stable isotope analysis to address such questions, but the isotopic landscape of Switzerland is so varied that there is no exact match. We can therefore also not exclude that they came from farther away. But a very likely scenario could be isolated alpine valleys."
Furtwängler and her colleagues hope to continue similar genomic analysis to better understand the movements of early populations during other important periods of human history in the region.
"One could make similar attempts to obtain a large dataset with dense temporal sampling for the transition at the beginning of the Neolithic times when agriculture appeared in the region," Furtwängler said.