Adventures in archaeological science: an exploration of oxygen and strontium isotopic variability on a micro- to macro-scale

Abstract

Isotopic analysis of human remains has become a key scientific technique employed to gather direct evidence of the diet and mobility of past populations. Geographic variation in the isotopic ratios for two elements in particular, oxygen (O) and strontium (Sr), provides a basis for measuring human mobility between regions with differing isotopic signatures. Human tooth enamel acts as a time capsule, locking in the signatures of childhood food and water, so is often the target of isotopic investigations. Understanding the level of variation in these two isotopic systems, O and Sr, is crucial to their use in archaeological mobility and provenancing studies. This thesis focuses on two aspects; micro-scale O isotopic variation in human tooth enamel and macro-scale Sr isotopic variation across islands, quantifying the amount of variation present, and investigating the causes of that variation. Intra-tooth O isotopic variation has been investigated using in situ analysis techniques. Archaeological human tooth samples have been used to provide a baseline value of intra-tooth O variation in a sample comparable with conventional bulk analysis, and to show the implications this variation has for the archaeological narrative. Modern human tooth samples, with known childhood histories, provide an indication of the range of intra-tooth variation seen in stationary and mobile individuals. Strontium isotope analysis of skeletal material requires a baseline of Sr isotopic variability in a region to test for mobility. In this study, robust bioavailable Sr isotope maps (isoscapes) for use in archaeological studies for the islands of Corsica and Grande-Terre, New Caledonia, have been created using soil and plant samples. A test of the Corsican isoscape using samples from the archaeological site of Campu Stefanu shows the applicability of these surfaces in tracing mobility. Underlying data on surface geology, geological age, coastal influences and a spatial assessment have been used to assess the factors driving this isotopic variation. While developing the methodology for this study, isotopic data useful for assessments of mobility at two additional archaeological sites, in France and Guadeloupe, were obtained. By combining O and Sr isotopic analyses of individuals from these sites, mobility was identified and further light shed on their life histories.