The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Microstructural analysis of linear enamel hypoplasia and estimation of stress episode duration in Jomon period dental remains from Hokkaido with comparisons to other cold-adapted foragers


1Anthropology, University of North Carolina Wilmington, 2Anthropology, The Ohio State University, 3Physical Anthropology, Kyoto University, 4Anatomy, Sapporo Medical University

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This study uses measurements and counts of the incremental microstructures of enamel (perikymata) to identify linear enamel hypoplasia (LEH) defects and estimate stress episode duration among Jomon period (ca. 5000 through 2000 BP) foragers from Hokkaido (HKJ). Results are compared with previously derived stress episode duration estimates among other cold-adapted foragers, specifically Neandertals from Europe and Inuit from Point Hope, Alaska. Each HKJ tooth was observed under a high resolution microscope. Perikymata spacing and enamel surface profiles were measured using VisionGauge software. LEH defects were identified according to accentuated perikymata and enamel surface depressions. All LEH defects were matched at chronological locations between teeth. Stress episode duration was estimated by multiplying the number of accentuated perikymata within each LEH defect by 8 and 7.4, representing the modal and mean periodicities for long-period striae in modern humans and Neandertals respectively. Box plots compared stress episode duration between the samples. The interquartile ranges for stress episode duration overlap in all three samples. Mean stress episode duration among the HKJ is reduced compared to the Point Hope Inuit and similar to mean stress episode duration among the European Neandertals. This suggests similarity in the distribution of stress episode duration between the HKJ and comparative groups, yet reduced average stress episode duration in the HKJ compared to Inuit sample. The results are consistent with greater availability of fall-back and complementary foods among the HKJ compared to Point Hope Inuit and similar availability/provisioning of these resources between the HKJ and European Neandertal samples.

National Science Foundation (BCS 1044950), Japan Society for the Promotion of Science (#07012)

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