Anthropology, University of Missouri
Thursday All day, Park Concourse
The cause of the abandonment of fortified Mississippian population centers is unclear, and has generated considerable debate among archaeologists. In this study, we use seek to contribute to these debates by examining the demographic impact of abandonment at two Middle Mississippian and two Late Mississippian sites in Missouri. We use theoretical and methodological advances in paleodemography and adult age estimation to compare the force of mortality and survivorship between sites and between sexes within sites, examine the effects of linear enamel hypoplasia on risk of death, and compare our results to previous life-table demographic analyses. Kaplan-Meier curves were fit to age estimates from transition analysis to generate empirical age-at-death distributions. Gompertz and Gompertz-Makeham hazard parameters were then plotted against the Kaplan-Meier curves to examine their fit, and then used to calculate force of mortality and survival functions. The hazard parameters suggest that the force of mortality was greatest for young females of reproductive age at all sites, increasing with greater site sizes. Using the Usher model and Cox semi-parametric hazard models, it was additionally demonstrated that individuals with linear enamel hypoplasias have a significantly greater age-specific risk of death than individuals without, suggesting that childhood frailty reflects, in part, reduced survivorship in these populations. Transition analysis and hazard models indicate a longer lifespan and more robust response to systematic insults than was implied by traditional demographic methods.