Genes from 5,000 years ago show that the Europeans of that crucial historical era were predominantly light-skinned — and mostly lactose-intolerant.
The findings, based on a rough analysis of genetic material extracted from the teeth of 101 ancient humans, provide snapshots of how mass migrations changed Europe's peoples during the Bronze Age, which lasted from around the year 3000 B.C. to 1000 B.C.
That era marked the transition from a predominantly hunter-gatherer way of life to a predominantly agricultural lifestyle, and the rise of urban civilizations ranging from Babylon to pharaonic Egypt to classical Greece and Rome.
The scientists behind the genetic survey, described in this week's issue of the journal Nature, wanted to find out how large a role migrations played in the cultural ferment. The results suggest they played a huge role.
"We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia," they reported.
Their analysis indicates that the era's most significant migration was the rapid expansion of a culture known as the Yamnaya, which pushed out from the steppes of the Caucasus and Ural regions into northern Europe in the early Bronze Age. The patterns of genetic signatures suggest that the Yamnaya interbred with the hunter-gatherers and farmers already living in northern Europe — influencing the development of another ancient set of peoples called the Corded Ware culture.