Speaker: Aaron Ragsdale of Integrative Biology
Description: It is now well-established that our species, Homo sapiens, emerged within Africa over the past hundreds of thousands of years before dispersing across the globe. However, apart from recent genetic discoveries of recontact between Neanderthals, Denisovans and humans, there is large uncertainty about the size, structure and connectivity of human populations during those early periods. Because the fossil record from this time is sparse, we rely on genomic data from present-day and ancient individuals to reconstruct the details of past population structure.
Here, we present a recent progress in our understanding of deep human history using genetic data from geographically and genetically diverse populations. We contrast models of archaic admixture with population structure, and discuss open questions in the field of human evolutionary history and paleoanthropology.
Bio: Aaron Ragsdale is an assistant professor in the Department of Integrative Biology. His research focuses on population genetic theory and computation methods for learning about demographic and evolutionary history from genomic data.
Explore More: In this paper, we use geographically and genetically diverse populations across Africa and Eurasia to reconstruct detailed demographic models for our species in the deep past. We find that a model that includes long-lasting population structure, with populations connected by ongoing migration, provides the best fit to the genetic data. In contrast to other recent studies, we do not find evidence for a substantial contribution from an unidentified “ghost” population within Africa (akin to Neanderthal and Denisovan contributions in Eurasia). This work is in collaboration with my former postdoc advisor Simon Gravel, at McGill University, Brenna Henn and Tim Weaver at UC Davis, and others.
Ragsdale Lab: https://apragsdale.github.io
Study Offers New Twist in How the First Humans Evolved: https://www.nytimes.com/2023/05/17/science/human-origins-africa.html
Did Early Humans Interbreed with a ‘Ghost’ Population?: https://www.nationalgeographic.com/premium/article/did-early-humans-interbreed-with-a-ghost-population