Ancient DNA from Guam and the peopling of the Pacific.

Humans reached the Mariana Islands in the western Pacific by ∼3,500 y ago, contemporaneous with or even earlier than the initial peopling of Polynesia. They crossed more than 2,000 km of open ocean to get there, whereas voyages of similar length did not occur anywhere else until more than 2,000 y later. Yet, the settlement of Polynesia has received far more attention than the settlement of the Marianas. There is uncertainty over both the origin of the first colonizers of the Marianas (with different lines of evidence suggesting variously the Philippines, Indonesia, New Guinea, or the Bismarck Archipelago) as well as what, if any, relationship they might have had with the first colonizers of Polynesia. To address these questions, we obtained ancient DNA data from two skeletons from the Ritidian Beach Cave Site in northern Guam, dating to ∼2,200 y ago. Analyses of complete mitochondrial DNA genome sequences and genome-wide SNP data strongly support ancestry from the Philippines, in agreement with some interpretations of the linguistic and archaeological evidence, but in contradiction to results based on computer simulations of sea voyaging. We also find a close link between the ancient Guam skeletons and early Lapita individuals from Vanuatu and Tonga, suggesting that the Marianas and Polynesia were colonized from the same source population, and raising the possibility that the Marianas played a role in the eventual settlement of Polynesia.

Validating earliest rice farming in the Indonesian Archipelago.

Preserved ancient botanical evidence in the form of rice phytoliths has confirmed that people farmed domesticated rice (Oryza sativa) in the interior of Sulawesi Island, Indonesia, by at least 3,500 years ago. This discovery helps to resolve a mystery about one of the region's major events in natural and cultural history, by documenting when rice farming spread into Indonesia, ultimately from a source in mainland China. At the Minanga Sipakko site in Sulawesi, preserved leaf and husk phytoliths of rice show the diagnostic morphology of domesticated varieties, and the discarded husks indicate on-site processing of the crops. The phytoliths were contained within an undisturbed, subsurface archaeological layer of red-slipped pottery, a marker for an evidently sudden cultural change in the region that multiple radiocarbon results extend back to 3,500 years ago. The results from Minanga Sipakko allow factual evaluation of previously untested hypotheses about the timing, geographic pattern, and cultural context of the spread of rice farming into Indonesia, as well as the contribution of external immigrants in this process.