Archaic introgression reveals human dispersals

The genome sequences of Neandertals and Denisovans have provided a wealth of new information about the origins, migrations, and interactions of ancient humans. These genomes have revealed that mixture between hominin groups was common: all modern humans outside Africa carry around 2% Neandertal DNA from a single major episode of Neandertal gene flow, while the ancestors of present-day Asians and Oceanians also met and mixed with multiple, genetically distinct Denisovan populations.

Archaeological evidence suggests multiple dispersals of modern humans out of Africa, with early fossils identified in East and Southeast Asia over 50 thousand years ago. In contrast, genomic studies indicate that all present-day non-African populations descend primarily from a single dispersal after ~50 ka, though the migration routes of ancestral populations across Eurasia and Oceania remain unclear. I will show how we are using the distribution of Neandertal and Denisovan ancestry in ancient and present-day modern humans to determine when, where and how often modern and archaic humans met and mixed. These findings offer a new perspective on the history of early modern human dispersals.