Republication from Nature
Localities, cultural associations, and approximate timeline of 101 sampled ancient individuals from Europe and Central Asia (left). Distribution of Early Bronze Age cultures Yamnaya, Corded Ware, and Afanasievo with arrows showing the Yamnaya expansions (top right). Middle and Late Bronze Age cultures Sintashta, Andronovo, Okunevo, and Karasuk with the eastward migration indicated (bottom right). Black markers represent chariot burials (2000–1800 bc) with similar horse cheek pieces, as evidence of expanding cultures. Tocharian is the second-oldest branch of Indo-European languages, preserved in Western China. CA, Copper Age; MN, Middle Neolithic; LN, Late Neolithic; EBA, Early Bronze Age; MBA, Middle Bronze Age; LBA, Late Bronze Age; IA, Iron Age; BAC, Battle Axe culture; CWC, Corded Ware culture.
The Bronze Age of Eurasia (around 3000–1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. 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. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought.