BBC: Making of Europe Unlocked by DNA

The story's written by Paul Rincon, on the BBC Science  News "page."

A study of remains from Central Europe suggests the foundations of the modern gene pool were laid down between 4,000 and 2,000 BC - in Neolithic times. ....

"What is intriguing is that the genetic markers of this first pan-European culture, which was clearly very successful, were then suddenly replaced around 4,500 years ago, and we don't know why. 

"Something major happened, and the hunt is now on to find out what that was."