Diet, Disease, and Developmental Defects: Examining the Role of Environmental Stress in the Etiology of Skeletal Anomalies.

OFFENBECKER, ADRIANNE MARIE. Diet, Disease, and Developmental Defects: Examining the Role of Environmental Stress in the Etiology of Skeletal Anomalies. (Under the direction of D. Troy Case, Scott M. Fitzpatrick, and Ann H. Ross). Frequencies of skeletal anomalies within families are noticeably elevated when compared to frequencies found in the general population, which indicates a strong genetic component in the etiology of these traits. Clinical studies, however, have demonstrated that certain environmental factors, particularly nutritional deficiency and disease, may trigger or enhance the genetic predisposition for developmental defects. While it is likely that both genetic and environmental factors contribute to the etiology of skeletal defects, it is unclear which specific traits are most sensitive to environmental stress. The primary objective of this study is to examine whether nutritional deficiency and disease cause elevated levels of developmental defects within a population. It is hypothesized that the more environmental stress experienced by a population, the higher its overall skeletal defect frequencies. To test this hypothesis, a total of 328 individuals from two archaeological cemeteries were examined for the presence of 46 skeletal defects. The samples are derived from temporally distinct Arikara sites whose inhabitants experienced varying levels of stress over several centuries. Previous research suggests that the earlier site, Mobridge (39WW1), is characterized by poorer overall health than the later period site, Larson (39WW2), and should therefore exhibit higher levels of skeletal anomalies if dietary deficiency and disease contribute significantly to the etiology of these traits. To better assess the varying levels of stress between the sample sites, the prevalence of three skeletal stress indicators, linear enamel hypoplasia, cribra orbitalia, and porotic hyperostosis were also compared between the sites. Defect and stress indicator frequencies were calculated for each sample and compared using the Fisher‟s Exact test. Mobridge and Larson were found to have statistically similar frequencies of linear enamel hypoplasia and cribra orbitalia, while porotic hyperostosis was not present in either sample. The only skeletal anomalies that varied significantly between the two sites were the os styloideum accessory bone and occipital vertebrae, which were more prevalent in the Mobridge sample. These findings indicate that environmental stress has minimal influence in the etiology of most developmental anomalies since the majority of skeletal defect frequencies were similar between the two Arikara samples. It is likely that the traits examined for this study are under strong genetic control and may therefore be useful for assessing genetic affinity in kinship analyses of archaeological cemeteries. However, it is also possible that stress levels were not divergent enough to elicit statistically significant differences between the samples, as the findings of the stress indicator assessment suggest. This highlights the need for further research into the etiology of developmental defects if they are to be utilized for anthropological research. Diet, Disease, and Developmental Defects: Examining the Role of Environmental Stress in the Etiology of Skeletal Anomalies by Adrianne Marie Offenbecker A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Arts