Quantitative evaluation of marine protein contribution in ancient diets based on nitrogen isotope ratios of individual amino acids in bone collagen: An investigation at the Kitakogane Jomon site |
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Authors: | Yuichi I. Naito Noah V. Honch Yoshito Chikaraishi Naohiko Ohkouchi Minoru Yoneda |
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Affiliation: | 1. Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277‐8562, Japan;2. Research Laboratory for Archaeology and the History of Art, School of Archaeology, University of Oxford OX1 3QY, UK;3. Institute of Biogeosciences, Japan Agency for Marine‐Earth Science and Technology, Yokosuka 237‐0061, Japan |
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Abstract: | Nitrogen stable isotopes analysis of individual bone collagen amino acids was applied to archeological samples as a new tool for assessing the composition of ancient human diets and calibrating radiocarbon dates. We used this technique to investigate human and faunal samples from the Kitakogane shell midden in Hokkaido, Japan (5,300–6,000 cal BP). Using compound‐specific nitrogen isotope analysis of individual amino acids, we aimed to estimate i) the quantitative contribution of marine and terrestrial protein to the human diet, and ii) the mean trophic level (TL) from which dietary protein was derived from marine ecosystems. Data were interpreted with reference to the amino acid trophic level (TLAA) model, which uses empirical amino acid δ15N from modern marine fauna to construct mathematical equations that predict the trophic position of organisms. The TLAA model produced realistic TL estimates for the Kitakogane marine animals. However, this model was not appropriate for the interpretation of human amino acid δ15N, as dietary protein is derived from both marine and terrestrial environments. Hence, we developed a series of relevant equations that considered the consumption of dietary resources from both ecosystems. Using these equations, the mean percentage of marine protein in the Kitakogane human diet was estimated to be 74%. Although this study is one of the first systematic investigations of amino acid δ15N in archeological bone collagen, we believe that this technique is extremely useful for TL reconstruction, palaeodietary interpretation, and the correction of marine reservoir effects for radiocarbon dating. Am J Phys Anthropol 143:31–40, 2010. © 2010 Wiley‐Liss, Inc. |
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Keywords: | amino acid nitrogen isotope ancient diet marine resource trophic level |
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