Professor of Genetics
Harvard Medical School
Toward a new history and geography of human genes informed by ancient DNA
Friday, March 6, 2020
Jordan Hall 124
Abstract: Beginning in 2010, it began to be possible to generate genome-scale data from ancient human remains, making it possible to ask and answer questions about the deep past—how people are related to each other, the extent to which changes evident in the archaeological record were propelled by movements and mixtures of people, and how adaptation of human populations occurred over time—that were simply not possible to address before. A measure of the importance of a new scientific instrument is the extent to which it changes our understanding of the world and challenges previous assumptions when we turn it to study something that could not be studied before, and by this measure, ancient DNA technology has some similarities to previous scientific instruments like the microscope.
Reich will begin his talk by discussing the evidence that modern humans today are a mixture of multiple highly differentiated populations that co-existed more than 50,000 years ago: most of our ancestors are African modern humans, but outside of Africa, people today also inherit substantial ancestry from archaic Neanderthals and an archaic group, the “Denisovans,” that was unknown prior to ancient DNA. He will present the evidence that “white people,” far from being a long-standing isolated group that has existed for tens of thousands of years, are instead a mixture of at least four populations that ten thousand years ago were as differentiated from each other as Europeans and East Asians. He will discuss how large scale movements of people from the Steppe north of the Black and Caspian Sea made a major impact on the populations of Europe and South Asia between 5000-3500 years ago, probably bringing with them the late Indo-European languages that are predominant in both regions today. Reich will also discuss how ancient DNA studies are now beginning to make an impact on our understanding of the human past through studies in South America, East and West Africa, and Southeast Asia and Remote Oceania in the Pacific just as they have on studies of western Eurasia. He will talk about how application of ancient DNA technology in many regions of the world is beginning to open up new avenues for dialogue between the sciences and the humanities. Reich will close his talk by sharing the (still unrealized) promise of ancient DNA studies to reveal as much about the nature of biological adaptation as it has revealed about history.