30 Oral - Platform Session #3 Speciation, Hybridization, and Introgression
Thursday June 09, 9:45 AM - 10:00 AM

The spatiotemporal patterns of major human admixture events during the European Holocene


Authors:
Manjusha Chintalapati 1; Nick Patterson 2; Priya Moorjani 1

Affiliations:
1) Department of Genetics, University of California Berkeley; 2) Broad Institute of Harvard and MIT, Cambridge,

Keywords:
Ancient DNA

Recent studies have shown that gene flow or admixture has been pervasive throughout human history. While several methods exist for dating admixture in contemporary populations, they are not suitable for sparse, low coverage data available from ancient specimens. To overcome this limitation, we developed DATES that leverages ancestry covariance patterns across the genome of a single individual to infer the timing of admixture. By performing simulations, we show that DATES provides reliable results under a range of demographic scenarios and outperforms available methods for ancient DNA applications. We apply DATES to ~1,100 ancient genomes to reconstruct gene flow events during the European Holocene. Present-day Europeans derive ancestry from three distinct groups, local Mesolithic hunter-gatherers, Anatolian farmers, and Yamnaya Steppe pastoralists. These ancestral groups were themselves admixed. By studying the genetic formation of Anatolian farmers, we infer that the gene flow related to Iranian Neolithic farmers occurred before 9,600 BCE, predating the advent of agriculture in Anatolia. We estimate the early Steppe pastoralist groups­­––Yamnaya and Afanasievo––were genetically formed more than a millennium before the start of steppe pastoralism, contrary to the archaeological evidence. Using ancient genomes across sixteen regions in Europe, we provide a fine-scale chronology of the Neolithization of Europe and the rapid spread of Steppe Pastoralist ancestry across Europe. We confirm previously discovered signal of the resurgence of hunter-gatherer ancestry during the Neolithic period and provide new details about the spread of Corded Ware and Bell Beaker Complexes across Europe. Our analyses provide new insights about the origin and spread of farming and Indo-European languages, highlighting the power of genomic dating methods to elucidate the legacy of human migrations.