New insights from old DNA into the colonization of the Pacific: Two case studies

This paper is based on a keynote lecture given at the Wellcome Trust meeting on Human Evolution: From Fossils to Ancient Genomes in April 2025. After giving some background on the colonization of the Pacific, I describe the results of two of our studies of ancient DNA. The first used ancient DNA from Eastern Indonesia to address questions about the timing of the admixture between indigenous Papuan groups and incoming Austronesian groups, and showed that this admixture likely occurred soon after the arrival of Austronesians in the region. However, there were unexpected differences in the ancestry of ancient samples from northern Eastern Indonesia (i.e., the North Moluccas) vs. southern Eastern Indonesia (i.e., the Nusa Tenggaras): the latter had ancestry from mainland Southeast Asia that was absent in the former. The second study investigated the origin and relationships of the early colonists of Guam, in the Marianas Archipelago, and found that the most probable origin was from the Philippines, in agreement with linguistic evidence and some interpretations of the archaeological (pottery) evidence, but contrary to the results of computer simulations of voyaging. These studies illustrate the power of ancient DNA analyses to address questions about population history, as well as to provide novel insights that were not realized from studies of modern populations.