TOOTHFIR: Presenting a dataset and a preliminary meta-analysis of Fourier Transform Infra-red Spectroscopy indices from archaeological and palaeontological tooth enamel

Abstract

The assessment of the preservation status of archaeological and palaeontological tooth enamel is of vital importance in the interpretation of isotopic and elemental analyses that underpin chronological, dietary, and mobility studies. Transmission and ATR Fourier Transform Infra-red Spectroscopy (FTIR) have provided an important means of studying the presence and crystallographic context of key structural groups in tooth enamel. However, differences in sample preparation and measurement methods prevent the setting of absolute references to assess tooth enamel preservation. Here, we present TOOTHFIR, a dataset of FTIR indices developed to study the crystal-chemical properties of enamel bioapatite, from Miocene, Pliocene, Pleistocene, Holocene, and modern samples. Using collected data, we conducted a preliminary statistical meta-analysis to assess inter-lab measurement variability (relying on modern samples) and the extent to which the mixed data remains useful in revealing diagenetic patterns. Our results confirmed significant variations with measurement methodology although it remained possible to observe broad relationships between the values for FTIR indices and environmental parameters. In this respect, we introduced the use of principal component analysis to summarize FTIR data. To improve data comparability and interpretation of preservation status, we suggest several measures.