Spatial variation of strontium isotopes (87Sr/86Sr) in the Maya region:: a tool for tracking ancient human migration

Strontium isotope ratios (Sr-87/Sr-86) in human bones and teeth have become a useful tool to study migration and sedentism of individuals from archaeological contexts. Here we analyzed Sr-87/Sr-86 of water, bedrock, soils, and plants across a broad geographic region to test the potential of this method in the ancient Maya area. Our aims were two-fold: first to test if the sources of dietary strontium (i.e., plants and water) in humans reflect the Sr-87/Sr-86 ratio of exposed bedrock, and second, to determine whether the ranges of Sr-87/Sr-86 values were sufficiently distinct among the principal Maya geocultural areas to infer past migration. We identified five distinct subregions on the basis of geologic maps and evaluated the variability of Sr-87/Sr-86 values (values given as mean Sr-87/Sr-86 2 standard deviations; number of samples): (1) Northern Lowlands (0.70888 +/- 0.00066; n=16); (2) Southern Lowlands (0.70770 +/- 0.00052; n=86); (3) Volcanic Highlands and Pacific Coast (0.70415 +/- 0.00023; n=34); (4) Metamorphic Province (0.70743 +/- 0.00572; n=50); and (5) the Maya Mountains of Belize (0.71327 +/- 0.00167; n=3). Although the sample size is small and overlap exists in Sr-87/Sr-86 values among some subregions, most areas can be readily distinguished from one another on the basis of strontium isotopes. These subregional Sr-87/Sr-16 differences provide archaeologists with a powerful tool to recognize geographic "outliers" in ancient Maya burials and thereby test hypotheses concerning the origin of specific individuals, inferred population migration patterns, and the possibility of outside cultural influences in the Maya region. (C) 2003 Elsevier Ltd. All rights reserved.