Hominin introgression in Island Southeast Asia and Sahul

Abstract

As the ancestors of modern non-African human populations left Africa around 65-50ka and dispersed across the world, they met and interbred with multiple hominin groups. The signatures of these events are preserved in the genomes of modern populations, and provide an eloquent record of the sequence and timing of these early migrations, with Asia proving a particularly complex area. In this study, we perform the most comprehensive genomic survey of modern-day human populations across Island South East Asia (ISEA) and Sahul, and provide a detailed picture of the admixture events taking place when so-called anatomically modern humans arrived in the area. At least three different Asian hominin groups appear to have been involved, including Denisovans. Several interbreeding events are inferred east of Wallace’s Line, the major biogeographical barrier in ISEA. Our results are consistent with archaeological evidence of widespread and early hominin presence in the area and suggest that isolated Denisovan groups inhabited different islands across ISEA, likely as a result of sea-level fluctuations during interglacial periods. Interestingly, of the currently known hominin fossils in the area, none has been associated with the Denisovans, who remain the most elusive member of the recent human family.