Native American gene flow into Polynesia predating Easter Island settlement

The possibility of voyaging contact between prehistoric Polynesians and Native Americans has long intrigued researchers. Proponents have pointed to New World crops, such as the sweet potato and bottle gourd, found in the Polynesian archaeological record, but nowhere else outside the pre-Columbian Americas(1–6), while critics have argued that these botanical dispersals need not have been human mediated(7). The Norwegian explorer Thor Heyerdahl controversially suggested that prehistoric South Americans played an important role in the settlement of east Polynesia and particularly Easter Island (Rapa Nui)(2). Several limited molecular genetic studies have reached opposing conclusions, and the possibility continues to be as hotly contested today as it was when first suggested(8–12). Here, for the first time, we analyze genome-wide variation in individuals from islands spanning Polynesia for signs of Native American admixture, analyzing 807 individuals from 17 island populations and 15 Pacific coast Native American groups. We find conclusive evidence for prehistoric contact of Polynesians with Native Americans (ca. 1200 CE) contemporaneous with the settlement of remote Oceania(13–15). Our analyses suggest strongly that a single contact event occurred in eastern Polynesia, prior to the settlement of Easter Island (Rapa Nui), between Polynesians and a Native American group most closely related to the indigenous inhabitants of present-day Colombia.