title: Influence of physiological stress on interpretations of stable isotope ratios in incremental dentine analysis: a study of two medieval Croatian populations, Dugopolje and Udbina
title: The influence of physiological stress on interpretations of stable isotope ratios in incremental dentine analysis: a study of two medieval Croatian populations, Dugopolje and Udbina
titleType: AlternativeTitle
Creators: name: Smith, Emma
Publisher: name: The University of Edinburgh
Year: 2025
Subjects: subject: Physiological stress
subject: Stable isotope ratios
subject: Incremental dentine analysis
subject: Medieval Croatian populations
subject: Linear enamel hypoplasia

description: Stable isotope analysis of incremental sections of tooth dentine has been integral to the development of the individual dietary life histories approach to investigating the past. As a tissue, dentine offers a greater temporal resolution (when sectioned incrementally) and resistance to environmental inhibition during its development. This makes dentine collagen is a complex tissue, at least compared to bone, recording more dietary and physiological changes through the individual’s life, and due to the inherent environmental resistance stress may also be recorded. While analysis of dentine can give a more detailed understanding of people as individuals, the potential for the occurrence of stress-related signals may be a hinderance to interpreting serial dentine stable isotope data. Currently there is no clear way to contend with, or at least mitigate, this complexity, which can make it more difficult to generate robust interpretations and may lead to information on life histories being missed or misinterpreted. The main aim of this research was to: (i) investigate the impact that physiological stress has on stable isotope ratios in incremental dentine collagen, (ii) in turn, assess how physiological stress may impact interpretations of diet and dietary changes; and (iii) to offer methodological suggestions to potentially contend with the complexity brought on by physiological stress. This was done primarily by comparing the carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S) stable isotope ratios of high-resolution microsections of dentine (from 33 individuals from two medieval Croatian populations, Dugopolje-Vučipolje-Crkvine and Udbina - Sveti Jakov) to formation ages of linear enamel hypoplasia (a physical marker of physiological stress). The results demonstrated a correlation between stress-related changes to stable isotope ratios and linear enamel hypoplasia. However, several areas where LEH was present coeval stress-related changes to the stable isotope profiles were not identified. This may suggest that in some cases physiological stress does not present as expected in stable isotope signals, which may be affected by other co-occurring factors (such as weaning). The addition of linear enamel hypoplasia formation times as a routine part of incremental methodology would help identify areas of stress that are not be evident from the isotopic ratios alone but could impact isotopic interpretations. Analysis also showed that interpretation of incremental data, particularly stress, is not a simple task and is subjective and would benefit from more than one observer interpreting the incremental stable isotope profiles.