Reconstructing patterns of systemic stress in a Jomon period subadult using incremental microstructures of enamel

Abstract

This study reconstructs systemic stress patterning using incremental microstructures of enamel in a subadult from the Yoshigo cemetery (3200 through 2800 BP), Aichi Prefecture, Japan, with the goal of providing an improved methodological and theoretical framework for interpreting systemic stress among Jomon people. High resolution impressions and replicas were collected for each anterior maxillary tooth. Each replica was studied under 50, 100, or 200× magnification on a measuring microscope. Perikymata spacing and enamel surface profiles were recorded using specialized software. Linear enamel hypoplasia (LEH) defects were identified as accentuated spacing in perikymata combined with a depression in the enamel surface. Each defect was placed within a chronological sequence based on decile location. Stress duration was estimated by counting the perikymata in the occlusal wall of each defect and multiplying that value by the modal periodicity for striae formation. Percentage of enamel growth disruption was estimated by dividing the number of perikymata within the occlusal wall of each matched defect by the total number of perikymata within the imbricational enamel. Eight LEH defects were chronologically matched. Chronology of LEH defects ranged between 1.2 through 3.5 years. Number of perikymata located within the occlusal wall of each defect ranged from one through 20. Estimated durations of stress ranged from 12 through 129.6 days. These durations overlapped with Neandertals, though Point Hope foragers had greater durations of stress with no overlap in interquartile ranges. Disrupted enamel growth ranged from 8.1% in the maxillary left canine to 50.7% in the maxillary right central incisor.