RESEARCH ARTICLE Multiproxy isotopic analyses of human skeletal material from Rapa Nui: Evaluating the evidence from carbonates, bulk collagen, and amino acids Amy S. Commendador 1,2 | Bruce P. Finney 2,3,4 | Benjamin T. Fuller 5 | Monica Tromp 6,7 | John V. Dudgeon 3 1 Idaho Museum of Natural History, Idaho State University, Pocatello, Idaho 2 Department of Biological Sciences, Idaho State University, Pocatello, Idaho 3 Center for Archaeology, Materials and Applied Spectroscopy, Idaho State University, Pocatello, Idaho 4 Department of Geosciences, Idaho State University, Pocatello, Idaho 5 Department of Archaeology and Heritage Studies, School of Culture and Society, Aarhus University, Højbjerg, Denmark 6 Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany 7 Department of Anatomy, University of Otago, Dunedin, New Zealand Correspondence Amy S. Commendador, Idaho Museum of Natural History, Idaho State University, Pocatello, Idaho. Email: commamy@isu.edu Abstract Objectives: Stable isotope ratio analysis of bulk bone collagen dominates research into past diet; however, bone carbonate and compound specific isotope analyses (CSIA) of amino acids provide alternative, yet complementary, lines of evidence toward that same research goal. Together they inform on different aspects of diet, allowing greater certainty in reconstructions. Here we present new data on carbon- ate isotopes for Rapa Nui and reevaluate prehistoric diet in the context of these new and previously published bulk collagen and CSIA data. Materials and methods: We analyzed carbon isotopes in bone carbonate from 28 pre- historic human teeth from Rapa Nui. These represent a subset of material examined previously for carbon and nitrogen isotope ratios in bulk collagen. We then reevaluate prehistoric diet in light of these and other published data. In addition, we analyzed car- bon and nitrogen isotope ratios in 28 modern plant specimens from Rapa Nui to better approximate the isotopic value of the terrestrial endmember. Results: Bulk data suggest a predominantly terrestrial diet, with the amount of marine sources incorporated varying though time. While previously argued to reveal greater amounts of marine consumption, reanalysis of recently published CSIA data suggests this result may relate to the proportion of carbon assimilated rather than consumed. Utilizing models incorporating concentration dependence for estimating dietary proportions results in much lower estimates of marine consumption, in line with findings of the bulk data. Discussion: While these data indicate a larger focus on terrestrial resources, limita- tions in all forms of analysis make it difficult to determine exact dietary contributions in this mixed system. Better understanding of the complex physiological processes governing isotopic routing and fractionation, and knowledge of appropriate isotopic endmember values are needed to advance this research. © 2019 Wiley Periodicals, Inc. KEYWORDS amino acids, bone carbonates, bone collagen, diet reconstruction, Rapa Nui Received: 12 April 2018 Revised: 24 April 2019 Accepted: 25 April 2019 DOI: 10.1002/ajpa.23851 Am J Phys Anthropol. 2019;1–16. wileyonlinelibrary.com/journal/ajpa © 2019 Wiley Periodicals, Inc. 1