The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Evidence for behavioral change between the Middle and Late/Final Jomon period using long bone diaphyseal robusticity

DAVID T. DILLON and DANIEL H. TEMPLE.

Department of Anthropology, University of North Carolina Wilmington

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This study documents long bone diaphyseal robusticity in Middle (5000 to 4000 BP) and Late/Final (4000 to 2300 BP) Jomon period skeletal remains from southwestern and eastern Honshu. Results are interpreted within the context of a climatic cooling episode documented around 4000 BP. Micro CT scans of humeri and femora were collected at 33% and 50% of biomechanical length for each bone respectively. Cross-sectional geometric properties including total subperiositeal area (TA), cortical area (CA), medullary area (MA), and polar second moment of area (J) were calculated using the Moment Macro program for Image J software. All measurements were standardized using appropriate parameters: TA, CA, and MA by body mass, J by long bone length2 ยท body mass. Comparisons between Middle and Late/Final Jomon period long bone diaphyses were performed separately for males and females. Differences in cross-sectional properties were evaluated between time periods using MANOVA methods. Significantly greater femoral CA (P < 0.025) and J (P < 0.079) as well as reduced MA (P < 0.001) were found in the Late/Final compared to Middle Jomon period males, while no differences were found in humeral diaphyseal robusticity between time periods for males or females. These results suggest increasing femoral diaphyseal robusticity among male members of the Late/Final Jomon community, specifically greater amounts of cortical bone and reductions of medullary area. This increase may reflect an increase in foraging distances, exposure to more rugged terrain during subsistence forays, or migration between sites. Recent strontium isotope analysis supports the latter assertion.

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