Strontium, oxygen, and carbon isotope variation in modern human dental enamel.

Esther Plomp,Isabella C. C. von Holstein,Gareth R. Davies,Suzanne J. A. Verdegaal‐Warmerdam,Lisette M. Kootker,Tim Forouzanfar

doi:10.1002/ajpa.24059

Abstract

ObjectivesIsotopic analyses using human dental enamel provide information on the mobility and diet of individuals in forensic and archeological studies. Thus far, no study has systematically examined intraindividual coupled strontium (Sr), oxygen (O), and carbon (C) isotope variation in human enamel or the effect that caries have on the isotopic integrity of the enamel. The inadequate quantification of isotopic variation affects interpretations and may constrain sample selection of elements affected by caries. This study aims to quantify the intraindividual isotopic variation and provides recommendations for enamel sampling methods.Material and MethodsThis study presents the first systematic results on intraindividual variation in Sr–O–C isotope composition and Sr concentration in modern human dental enamel of third molars (affected and unaffected by caries). A multiloci sampling approach (n = 6–20) was used to analyze surface and inner enamel, employing thermal ionization mass spectrometry (TIMS) and isotope ratio mass spectrometry (IRMS). Third molars were analyzed from 47 individuals from the Netherlands, Iceland, the United States, the Caribbean, Colombia, Somalia, and South Africa.ResultsIntradental isotopic variation in modern Dutch dental elements was recorded for Sr, O, and C and exceeded the variation introduced by the analytical error. Single loci and bulk sampling approaches of third molars established that a single analysis is only representative of the bulk Sr isotope composition in 60% of the elements analyzed. Dental elements affected by caries showed twice the variation seen in unaffected dental elements. Caries did not consistently incorporate the isotopic composition of the geographical environment in which they developed.DiscussionThe isotopic variability recorded in unaffected inner enamel indicates that variations greater than 0.000200 for 87Sr/86Sr and larger than 2‰ for δ18O and δ13C are required to demonstrate changes in modern Dutch human diet or geographic location.

Highlights

Human dental enamel contains information regarding the geographical origin and dietary patterns of an individual
This study aims to determine if: 1. The variation of Sr–O–C isotope composition in modern human dental enamel is in the same order of magnitude between various sample locations within the same dental element, as well as within other dental elements of the same individual
To evaluate the intraindividual variation in Sr–O–C isotopes in modern human enamel, the results of the multiloci sampling approach (Table 2) have been organized based on the density of the sampling approach

Summary

Introduction

Human dental enamel contains information regarding the geographical origin and dietary patterns of an individual. Strontium (Sr), oxygen (O), and carbon (C) isotope analyses are established techniques to infer information about human provenance (87Sr/86Sr (e.g., Bentley, 2006), δ18O (e.g., Blumenthal et al, 2014; Bowen, 2010; Lightfoot & O'Connell, 2016; Pellegrini, Pouncett, Jay, Pearson, & Richards, 2016); and diet (δ13C, for example, Chesson et al, 2018; France & Owsley, 2015; Lee-Thorp, 2008) These isotopic analyses have been successfully applied to both modern (e.g., Font, Van Der Peijl, Van Leuwen, Van Wetten, & Davies, 2015; Vautour, Poirier, & Widory, 2015) and archeological individuals (e.g., Bataille et al, 2018; Kootker, Mbeki, Morris, Kars, & Davies, 2016; Laffoon et al, 2017; Panagiotopoulou et al, 2018; Snoeck et al, 2018)

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