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David Reich
Professor of Genetics, Harvard Medical School
Professor of Human Evolutionary Biology
Insights from Ancient DNA Time Series Data on the Landscape of Natural Selection in Humans in the Last 10,000 Years (David Reich and lead analyst Ali Akbari).
Abstract: The number of ancient humans with genome-wide data has increased from nothing before 2010 to more than ten thousand individuals with published data today. While the ancient DNA revolution has had a transformative impact on our understanding of human migrations and population mixtures, it has not yet realized the promise of time series data for revealing patterns of human adaptation, because sample sizes have until recently been too small to track frequency changes over time with high precision. Here we analyze genome-wide data from more than 6000 ancient individuals largely from the last 10,000 years of European ancestry. By using a dataset about an order of magnitude larger than any dataset previously used in an ancient DNA scan for selection, and deploying several new methodologies, we increase the number of locations with signals of selection from 25 in the largest previous scan of selection, to 428. We identify previously unknown signals of adaptation at specific loci such as the Trichohyalin variant where we detect selection against a propensity toward balding. We detect many signals of polygenic adaptation, including on traits . Finally we find qualitative evidence for changes in the nature of natural selection in humans from the period of the Bronze Age around 4000 years ago to the historic period beginning around 2000 years ago.