Hunter-gatherer genomes reveal diverse demographic trajectories during the rise of farming in Eastern Africa
Shyamalika Gopalan, Richard E. W. Berl, Justin W. Myrick, Zachary H. Garfield, Austin W. Reynolds, Barnabas K. Bafens, Gillian M. Belbin, Mira Mastoras, Cole Williams, Michelle Daya, Akmel N. Negash, Marcus W. Feldman, Barry S. Hewlett, Brenna M. Henn
Abstract
We generated genome-wide data from the Chabu and four neighboring populations, the Majang, Shekkacho, Bench, and Sheko, to characterize their genetic ancestry and estimate their effective population sizes over the last 60 generations. We show that the Chabu are a distinct population closely related to ancient people who occupied Southwest Ethiopia >4,500 years ago. Furthermore, the Chabu are undergoing a severe population bottleneck, which began approximately 1,400 years ago. By analyzing eleven Eastern African populations, we find evidence for divergent demographic trajectories among hunter-gatherer-descendant groups. Our results illustrate that although foragers respond to encroaching agriculture and pastoralism with multiple strategies, including cultural adoption of agropastoralism, gene flow, and economic specialization, they often face population decline.