Constructing A New Incremental Isotopic Methodology For Human Dental Enamel: A Preliminary Examination

The application of incremental enamel sampling on human dental enamel allows researchers to observe how isotopic values may vary over an individual’s early life. For archaeologists, this means we can observe how an individual’s diet and geographical mobility may have changed over time. Currently, incremental isotope studies on human enamel primarily use in-situ techniques, which while allowing for small and targeted analysis, are limited in access, precision or applicable isotopes. An alternative is the use of micro-milling techniques, which are more accessible and cost-efficient. Whilst milling techniques are commonly used on faunal dental enamel (i.e., sheep and cattle), the amelogenesis process in human dentition is shorter and more intricate. As such, placing enamel increments, removed by milling, into a chronological order is difficult without the knowledge of that tooth’s specific growth pattern. Whilst the construction of such a methodology is challenging, it is essential to investigate if incremental milling techniques can be viable on human dental enamel, to enable high resolution dietary and mobility reconstructions for humans.

The aim of this study is to produce an incremental sampling technique for the enamel of human molars and canines, to reveal variations in strontium (Sr), oxygen (O), and carbon (C) isotopic ratios during the tooth enamel formation period. This technique uses milling guided by thin-sections of the enamel to ensure a developmentally informed sampling strategy. Preliminary results from a combination of both modern and archaeological samples reveals a promising indication that enamel increments can be successfully sampled along a human tooth enamel growth axis. However, the growth pattern of human tooth enamel limits the number of increments that can be milled in a resolvable time series. As such, this study provides a critical evaluation of the proposed technique, and a plan of how to increase the resolution of the methodology in our future research.

This project is supported by the European Research Council: LUMIERE - Landscape Use and Mobility In EuRopE - Bridging the gap between cremation and inhumation (Agreement No. 948913