Denisova Admixture and the First Modern Human Dispersals into Southeast Asia and Oceania

Reich et al. recently published a new paper on Denisova admixture in Asia and Oceania in The American Journal of Human Genetics. They sampled 33 additional populations to those that were studied in previous papers to describe a more extensive migratory and population model for East and Southeast Asia and Oceania. The research showed that East Asian and western Indonesian populations did not show evidence of Denisovan material, which was present in aboriginal Australians, Polynesians, east Indonesians, and others. Therefore, they conclude that Denisova interbreeding with present-day humans occurred in Southeast Asia and happened before ancestors of present-day East Asians were in Southeast Asia. This challenges the model that the Denisova gene flow occurred in mainland Asia, the supposed geographical limits of the Denisova, and then spread to Southeast Asia; the authors instead suggest that this gene flow happened in Southeast Asia itself. These results broaden the previously-described geographic range of the Denisovans to more areas of Asia, and demonstrate their large "ecological range, from Siberia to tropical Asia."