The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)

Assessing the Role of Migration in Cahokia’s Population using Strontium Isotope Analysis


Department of Anthropology, University of Illinois

March 26, 2015 , Gateway Ballroom 3 Add to calendar

This vast cultural center of Cahokia arose quickly, with a dramatic population increase relative to the preceding Late Woodland. Population estimates for Cahokia are as high as 20,000 individuals, a number that cannot be accounted for by in-situ birth rates or the consolidation of local settlements prior to Cahokia’s formation. This growth necessitates an influx of “new” people to the region.

Strontium isotope analysis of archaeological, small, and non-migratory mammal teeth from the American Bottom of Illinois refined the local strontium signature for the Cahokia region (Slater et al., J. Arch. Sci. 2014). Analysis of human teeth from multiple mound and cemetery contexts at Cahokia were compared to this range and about one-third of individuals sampled had ‘non-local’ strontium isotope ratios, indicating that they had migrated to the area.

This poster presents results of new strontium isotope analyses carried out to identify where Cahokia’s migrants were coming from. Modern mussel shell from the Illinois and Mississippi Rivers, as well as micro-mammal teeth from archaeological sites in Illinois and other locations within Cahokia’s interaction sphere, were analyzed to better characterize the isotopic variation in these possible population source areas. Results suggest that migrants may have come from areas in the Illinois River Valley and Wisconsin, though some individuals have strontium ratios that fall outside these ranges and must have came from elsewhere. Ultimately, these results indicate that migrants came from multiple different regions and likely shared few personal bonds, necessitating the development of novel religious, social, and political systems at Cahokia.

This research was supported and funded by the Illinois State Archaeological Survey (ISAS) and the Prairie Research Institute (PRI) at the University of Illinois, Urbana-Champaign.