Ancient DNA unravels Europe’s genetic diversity

Ancient DNA recovered from a time series of skeletons in Germany spanning 4,000 years of prehistory has been used to reconstruct the first detailed genetic history of modern-day Europeans.

The study reveals dramatic population changes with waves of prehistoric migration, not only from the accepted path via the Near East but also from Western and Eastern Europe.

In an international collaboration between scientists at the University of Mainz, the State Heritage Museum in Halle in Germany, the National Geographic Society’s genographic project and the University of Adelaide in Australia, the teams used mitochondrial DNA, that is, maternally inherited DNA, extracted from bone and teeth samples from 364 prehistoric human skeletons – 10 times more than previous ancient DNA studies.

“This is the largest and most detailed genetic time series of Europe yet created, allowing us to establish a complete genetic chronology,” the scientists say.

“Focusing on this small but highly important geographic region meant we could generate a gapless record and directly observe genetic changes in ‘real-time’ from 7,500 to 3,500 years ago, from the earliest farmers to the early Bronze Age.”

The study showed that a simple mix of indigenous hunter-gatherers and incoming Near Eastern farmers could not explain modern-day diversity alone. The genetic results were much more complex and instead the researchers found that two particular cultures at the brink of the Bronze Age 4,200 years ago had a marked role in the formation of Central Europe’s genetic makeup.

“What is intriguing is that the genetic signals can be directly compared with the changes in material culture seen in the archaeological record,” said Professor Kurt Alt of the University of Mainz.

“It is fascinating to see genetic changes when certain cultures expanded vastly, clearly revealing interactions across very large distances.”

These included migrations from both Western and Eastern Europe towards the end of the Stone Age, through expanding cultures such as the Bell Beaker and the Corded Ware, which were named after their pots. This transect through time produced a wealth of information about the genetic history of modern Europeans.

There was a period of stasis after farming became established and suitable areas were settled, and then sudden turnovers during less stable times or when economic factors changed, such as the increasing importance of metal ores and secondary farming products.

While the genetic signal of the first farming populations became increasingly diluted over time, the original hunter-gatherers made a surprising comeback.

Yet the scientists say none of the dynamic changes could have been inferred from modern-day genetic data alone, highlighting the potential power of combining ancient DNA studies with archaeology to reconstruct human evolutionary history.

A report of the study was published in Science magazine.