Origin and diet of inhabitants of the Pacific Coast of Southern Mexico during the Classic Period - Sr, C and N isotopes

Abstract This paper presents the results of a multi-proxy analysis of human remains from the Classic Period in the Pacific Coast region of Southern Mexico. The strontium isotopic composition of bone, dentine and enamel samples is combined with C and N isotope determinations on remains from four individuals recovered from burials dated to 595–950 CE. The possible impact of diagenesis, in this context probably related to the use of modern fertilizers, on the results is also evaluated. The combination of Sr, C and N isotope results show that the individuals examined here were likely local people who were consuming maize-based terrestrial food. The discrepancy observed between the strontium isotopic composition of these four individuals and the local strontium signature is best explained by a contribution from sea salt as well as the alkali solution used in the nixtamalization process. This study emphasizes the importance of considering the diet together with the strontium isotopes when attempting to understand migration, especially in coastal environments. It also shows that pre-treatment with acetic acid does not remove all trace of diagenesis.