DNA recovered from ancient skeletons reveals that the genetic makeup of modern Europe was established around 4,500 years ago in the mid-Neolithic, and not by the first farmers who arrived in the area around 7,500 years ago or by earlier hunter-gatherer groups. (Read about Europe's oldest known town.)
"The genetics show that something around that point caused the genetic signatures of previous populations to disappear," said Alan Cooper, director of the Australian Centre for Ancient DNA at the University of Adelaide, where the research was performed.
"However, we don't know what happened or why, and [the mid-Neolithic] has not been previously identified as [a time] of major change," he said.
Furthermore, the origins of the mid-Neolithic populations that did form the basis of modern Europe are also unknown.
"This population moves in around 4,000 to 5,000 years ago, but where it came from remains a mystery, as we can't see anything like it in the areas surrounding Europe," Cooper said.
The surprising findings are part of a new study, published in this week's issue of the journal Nature Communications, that provides the first detailed genetic history of modern Europe.