Developing A New Incremental Isotopic Methodology For Human Dental Enamel to Track Childhood Mobility.

Archeodemography has benefited from isotope studies showing how it was possible to identify if individuals were locals or not. Still, new developments allow to go deeper and also discuss an individual's mobility over their lifetime. The application of sequential sampling on human dental enamel allows researchers to observe how isotopic values vary over an individual’s early life. This means one can examine how an individual’s 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 frequently used on hypsodont dental enamel (i.e. sheep), amelogenesis in human dentition is shorter and far more complex. 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 mobility reconstructions for humans.

The aim of this study is to produce a thin-section guided incremental sampling technique guided by thin-sections for the enamel of human molars and canines, to reveal variations in strontium (Sr), oxygen (O), and carbon (C) isotopic values during the tooth enamel formation period. Preliminary results are promising, revealing that isotopic values can be tracked in a time-series within an individuals early life. However, this investigation did find that 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 also provides a critical evaluation of the proposed technique, and a plan of how to increase the resolution of the methodology in our future research.