Testing the validity of stable isotope analyses of dental calculus as a proxy in paleodietary studies

摘要

Stable isotopic analyses (delta C-13, delta N-15) of dental calculus have been suggested as a proxy for the study of diet of ancient populations but questions about their validity have been raised. Here we test this question, introducing significant improvements in the analysis of delta C-13 and comparing our results for delta C-13 and delta N-15 of calculus with corresponding analyses of associated well-preserved bone which are widely believed to provide reliable paleodiet values. The content of organic material in calculus is decreased by similar to 75% compared with modern calculus, resulting in diagenetic changes to delta C-13 and delta N-15 of organic matter. Neither delta C-13 nor delta N-15 analyses of the organic component of calculus provide accurate estimates of paleodiet. Although delta N-15 values of dental calculus are correlated with delta N-15 values of bone collagen from the same individual, it is clear that they have been greatly affected by diagenesis, as shown by a correlation between C/N ratio and delta N-15. The inorganic (mineral-bound) carbon component of calculus, analyzed separately from the organic component, gave delta C-13 values slightly offset from delta C-13 values of CO3 in bone mineral. Thus it alone appears to have potential as a dietary proxy. (C) 2018 Elsevier Ltd. All rights reserved.