Paleodemography of the Larson Site (39WW2) Cemetery: How Age-at-Death Methods Influence Model Estimation

The Arikara are one of the last Native American tribes to have direct contact with Europeans. Prior to westward expansion of Euro-American settlers, the Arikara served as middlemen in a complex trade network that brought European goods to the Upper Plains in exchange for fur and food items. In the 18^th century with a growing European presence in the region, the Arikara experienced drastic bio-cultural and socio-political destabilization leading to population decline. However, these transitions are unclear because of limited written records prior to the early 19^th century. Several hypotheses have been proposed to account for the near extinction of the Arikara tribe including warfare, inter- and intra-tribal conflict, disease, and resource stress.

This research sought to better understand the population dynamics within the Larson Site. The Larson Site (39WW2) cemetery, a relatively unbiased and well-preserved skeletal assemblage (N=643), was re-analyzed to evaluate the demographic variability associated with increased European presence. The main focus of this research demonstrates how age-at-death estimation methods impact the mortality profiles and demographic measures derived from them. Traditional phase-base approaches, long bone skeletal development, Transition Analysis, and multifactorial approaches for both juvenile and adult individuals were used to compute age-at-death estimates for each individual within the cemetery. The point age-at-death estimates served as the basis for survival analysis via parametric hazards models. The Siler model was used to understand the overall pattern of mortality, while the Gompertz and Gompertz-Makeham models were used to explore adult-specific mortality patterns. The results indicate that the high number of juveniles and the relatively low survivorship of adults imply that the population may have been experiencing a mortality event, like an epidemic. The high fertility and death rate must be incorporated into future models. Also, the overall patterning of the adult mortality is obscuring any sex-specific adult mortality pattern.

This research is the beginning of a larger project to explore the utility of multi-state models of morbidity and mortality to better explain the population dynamics within the Larson Site and between the Larson and other Arikara villages.