The settlement of the Eastern Pacific (the “Polynesian triangle” from Hawaii to Rapa Nui to Aotearoa New Zealand) represents the last great phase of prehistoric human exploration and expansion. Despite this incredible feat, we know incredibly little about immediate and long-term post-arrival impacts on human physiology and health. Arrival in unique locations with varied access to resources, new disease exposures, and altered diets likely resulted in differential adaptive strategies across distinct archipelagos.

A new method – assessing ancient oral microbiomes within calcified dental plaque (calculus) – can provide insights into how humans adapted to new environments. Here, we sequenced ancient DNA preserved within dental calculus from three different Pacific Island Nations (Palau, Tahiti, and Aotearoa) in concert with local collaborators and communities. Distinct oral microbial communities were linked to the arrival in Central-East Polynesia, as well as settlement on individual archipelagos (i.e., in Tahiti), suggesting that settling in new locations may have altered microbes within these Ancestors. A key oral species within the Anaerolineaceae family also corroborated large-scale patterns of human migration, suggesting that these microbial signatures can potentially be leveraged to identify Pacific Islander Ancestors with minimally destructive sampling approaches. Overall, our work reveals how microbial signatures in Ancestors can illuminate novel insights into human adaptation to new environments.

Presentation by Dr. Laura Weyrich, associate professor of anthropology at Penn State University.