Genetic History of Modern Day Europeans Reconstructed With Ancient DNA

Researchers have successfully reconstructed the first detailed genetic history of modern-day Europeans using ancient DNA recovered from a series of skeletons in Germany that represent 4000 years of prehistory.

In the new finding, Dr.Wofgang Haak the lead researcher from the Australian Centre for Ancient DNA (ACAD), at the University of Adelaide in collaboration with researchers from the University of Mainz, the State Heritage Museum in Halle and National Geographic Society's Genographic Project, worked on the mitochondria DNA (mtDNA) samples that were extracted from bones and teeth of 36 prehistoric human skeletons from the Mittelelbe-Saale region of Germany.

"This is the largest and most detailed genetic time series of Europe yet created, allowing us to establish a complete genetic chronology. Focussing 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," Dr. Haak said in a press statement.

By analysing the mtDNA, that is solely inherited from the mother and carries the genetic information in the cells, the team yielded complex results. They discovered that some 7,500 years ago the indigenous hunter and farmer gatherers who were mostly Central Europe's native ancestors were edged out by migrants from Anatolia (modern day Turkey)

Most of the hunters belonged to the haplogroup U maternal lineage. Farmers, on the other hand, belonged to a selected genetic lineage that were mostly from the Near East. The introduction of the farming community to Scandinavia nearly 6,100 years ago overlapped with the emergence of Neolithic mtDNA in that region, reports BBC.

Further DNA evidence of the maternal lineage reveals that nearly a millennium later, the number of native farmers in Central Europe dropped and hunters and gatherers bounced back after a span of thousand years. The researchers assume climate change and diseases are the two factors that caused that shift but further studies are needed to confirm this.

 Another study reported in the journal Science was conducted by Ruth Bollongino from the University of Mainz, Germany. Bollongino claims that the hunters and gatherers co-existed for nearly 2000 years after the initiation of agriculture in that region. But interbreeding between the two groups never took place.

Maternal lineages found 4,800 years ago that were believed to have emerged from the East, spread to the region and had the characteristics of the Corded Ware people. This name comes from the ornamentation of its characteristics pottery.

On comparing the mtDNA of the Corded Ware people with that of the modern population, the researchers found a resemblance with the present day groups in Eastern Europe, the Baltic region as well as the Caucasus.

As certain cultures expanded, genetic changes took place. Toward the end of the Stone Age, people migrated from Western and Eastern Europe through expanding cultures like Bell Beaker and Corded Ware.

"This transect through time has produced a wealth of information about the genetic history of modern Europeans," ACAD Director Professor Alan Cooper explains. "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 becomes increasingly diluted over time, we see the original hunter-gatherers make a surprising comeback."

Analysis of the two studies conducted reveal that the present day European DNA is a mix of genetic lineage from both hunter and farmer migrants.

The study was published online in the journal Science.