Person:

Harney, Eadaoin

Ancient DNA makes it possible to directly witness natural selection by analyzing samples from populations before, during and after adaptation events. Here we report the first scan for selection using ancient DNA, capitalizing on the largest genome-wide dataset yet assembled: 230 West Eurasians dating to between 6500 and 1000 BCE, including 163 with newly reported data. The new samples include the first genome-wide data from the Anatolian Neolithic culture whose genetic material we extracted from the DNA-rich petrous bone and who we show were members of the population that was the source of Europe’s first farmers. We also report a complete transect of the steppe region in Samara between 5500 and 1200 BCE that allows us to recognize admixture from at least two external sources into steppe populations during this period. We detect selection at loci associated with diet, pigmentation and immunity, and two independent episodes of selection on height.

Ancient DNA studies have established that Neolithic European populations were descended from Anatolian migrants1–8 who received a limited amount of admixture from resident hunter-gatherers3–5,9. Many open questions remain, however, about the spatial and temporal dynamics of population interactions and admixture during the Neolithic period. Using the highest-resolution genome-wide ancient DNA data set assembled to date—a total of 180 samples, 130 newly reported here, from the Neolithic and Chalcolithic of Hungary (6000–2900 BCE, n = 100), Germany (5500–3000 BCE, n = 42), and Spain (5500–2200 BCE, n = 38)—we investigate the population dynamics of Neolithization across Europe. We find that genetic diversity was shaped predominantly by local processes, with varied sources and proportions of hunter-gatherer ancestry among the three regions and through time. Admixture between groups with different ancestry profiles was pervasive and resulted in observable population transformation across almost all cultural transitions. Our results shed new light on the ways that gene flow reshaped European populations throughout the Neolithic period and demonstrate the potential of time-series-based sampling and modeling approaches to elucidate multiple dimensions of historical population interactions.