Relationships between Sr isotopic composition of mineral waters and deciduous human teeth: a contribution to human mobility and food traceability studies in Italy

In recent years, isotopic studies have provided a huge contribution to archaeology. Several studies, carried out in variable localities of the world, have focused their attention on human mobility, to identify non local individuals from ancient burials and reconstruct their migrations, by measuring the strontium isotope ratios (87Sr/86Sr) of their teeth enamel. This method is based on the premise that rocks display variable 87Sr/86Sr ratios depending on several factors associated with the geological characteristics of the site, i.e., age and type of the parent rocks (e.g., Price & Gestsdóttir, 2006; Kenoyer et al., 2013), and original rubidium (Rb) content. The bioavailable Sr present in soil and groundwater is incorporated into local plants and, through the food chain, enters the human body. On this basis, 87Sr/86Sr signatures in human tissue mirror the 87Sr/86Sr values of water, plants and consumed food, which in turn reflect that of bedrock of a given region (Ericson, 1985). In this study, Sr isotope ratios were measured on commercial mineral waters from variable Italian water springs, on soils and plants from the Neapolitan area, and on teeth enamel of children. The latter were born and still live in the Neapolitan area (south Italy), so that constraints on their childhood diet are available. The aim was to discriminate among the contributions of soil, water, food etc., and identify the main one affecting the isotopic signature of teeth enamel. The results of this investigation will be important for human mobility studies because they will allow understanding to which extent Sr isotopes can be effectively used for i) discriminating non-local from local individuals, and ii) assessing the effects on the modern society of a diet based on food from different geographic areas. Ericson, J.E. (1985): Strontium isotope characterization in the study of prehistoric human ecology. J. Hum. Evol., 14, 503-514. Kenoyer, J.M, Price, T.D., Burton, J.H. (2013): A new approach to tracking connections between the Indus Valley and Mesopotamia: initial results of Strontium isotope analyses from Harappa and Ur. J. Archaeol. Sci., 40, 2286-2297. Price, T.D. & Gestsdóttir, H. (2006): The first settlers of Iceland: an isotopic approach to colonisation. Antiquity, 80, 130-144.