The demographic structure of present-day Europe and Asia is the result of wide-ranging population migrations, and the resulting cultural changes that occurred during the Bronze Age, genetic analysis of ancient Eurasians shows.
Between 3000 BC and 1000 BC, new technologies and social tradition spread outward from the steppes between the Caspian Sea and the Black Sea into all of Europe and Asia, sequencing of ancient genomes indicates.
A study appearing in the journal Nature, "Population genomics of Bronze Age Eurasia," has generated the most extensive ancient genomic study to date.
The study was conducted to address a long-standing debate about whether the cultural changes that set the stage for modern Eurasia come from the spread of ideas through existing populations or through mass physical migrations of ancient humans, its authors say.
Morten Allentoft, a geneticist at the Center for GeoGenetics at the Natural History Museum of Denmark in Copenhagen, led the research that analyzed more than 600 samples of Bronze Age human remains.
"Both archaeologists and linguists have had theories about how cultures and languages have spread in our part of the world," he says. "We geneticists have now collaborated with them to publish an explanation based on a record amount of DNA analyses of skeletons from the Bronze Age."
The most important result of the work is the finding that the transition into the Bronze Age on the road to modern Eurasia "certainly involved large-scale human migrations," Allentoft says.
In one example, the researchers say they determined ancient members of the Yamnaya culture, a population of nomadic herders originating about 5,000 years ago in what today is southwestern Russia, are genetically indistinguishable from the peoples of the slightly younger Afanasievo culture, which inhabited a region thousands of miles further east.
Significant economic and social changes occurred "at the beginning of the third millennium BC, from the Urals north to Scandinavia, as old Neolithic farming cultures were replaced by a completely new perception of family, property and personhood," explains researcher Kristian Kristiansen of the University of Gothenburg in Sweden.
"I and other archaeologists share the opinion that these changes came about as a result of massive migrations," he says.
Such migrations can also explain the origins of the language families of northern Europe, the researchers suggest.
The scale of the study was made possible by new gene sequencing technologies than can conduct wide-ranging analysis quickly and inexpensively, notes Greger Larson, an evolutionary geneticist at the University of Oxford in England.
"It's an interesting time, because the technology is moving faster than our ability to ask questions of it," he says. "Let's just sequence everything and ask questions later."
