Geochemical Journal, Vol. 48 (No. 4), pp. e15-e19, 2014
Yu Itahashi1*, Yoshito Chikaraishi2, Naohiko Ohkouchi2 and Minoru Yoneda1,3
1Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan
2Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan
3The University Museum, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
(Received April 22, 2014; Accepted May 23, 2014; Online published June 23, 2014)
We determined the stable nitrogen isotopic composition (δ15N) of amino acids in bone collagen from samples of three archaeological herbivores (cattle, sheep, and goats), collected from the Tell Ain el-Kerkh Neolithic site in Syria. Bulk collagen δ15N values exhibited significant differences between the three species (by up to 3.2‰), and were strongly correlated with those of glycine (R2 = 0.87), the most abundant amino acid in bone collagen. On the other hand, the δ15N values of two other minor amino acids (glutamic acid and phenylalanine) in the different samples were within narrow ranges (0.9‰ and 0.5‰, respectively), and exhibited either weak or no correlation with those of bulk collagen. The trophic position estimated by the δ15N values of glutamic acid and phenylalanine (2.0 ± 0.1) is consistent with that of herbivores. These results suggest that the δ15N values of bulk bone collagen may vary among herbivores, partly on account of their differing amino acid compositions, whereas the trophic position of different herbivores is faithfully preserved in the δ15N values of glutamic acid and phenylalanine.
Key words: nitrogen isotopic composition, amino acid, trophic position, terrestrial herbivores, ancient diet