The two genetic studies didn’t detect signs of just one major migration into Europe. They also revealed an unsuspected mobility in Bronze Age populations. Central Asia appears to have been especially volatile. As the evolutionary biologist Eske Willerslev – one of the leads of the Copenhagen study – told me, it is genetically ‘the most dynamic place’ he’s ever seen, with ‘four distinct populations’ replacing one another in turn. An initial group of Eurasian hunter-gatherers were succeeded by people from the Caucasus, who were in turn replaced by Northern Europeans and then by East Asians.