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

Secular change in the femoral head in modern Americans


Medical Assisting, South College

Saturday Afternoon, Forum Suite Add to calendar

The recognition of secular changes in various aspects of the skeleton has been an area of continuing investigation for anthropologists as the presence of secular change can provide indications of populational response to ongoing environmental transitions. Trend comparison among cohorts reveals degrees of change experienced among groups within a single population or between groups. Studies typically employ linear regression to identify morphological changes over time; however trends are not necessarily linear in nature. In this study, secular changes in the femoral maximum vertical head diameter (MVHD) of American males and females were evaluated through the application of advanced statistical methods appropriate for time-series data and the identification of trends

Femoral head diameters of 19th Century and modern Americans (n=1,217) were analyzed from the Robert J. Terry Anatomical Collection, the M. F. Ericksen Collection, and theUniversity ofTennessee Forensic Data Bank. Two cohorts categorized by sex were evaluated for autocorrelation before performing additional statistical analyses. Statistical evaluation for the male sample was executed via an Autoregressive Integrated Moving Average (ARIMA) model of the average MVHD variable on the year-of-birth variable, and a subsequent regression analysis of lag first-differences on a five year year-of-birth variable. ARIMA results indicate the male average head diameter appears to fluctuate in size over time. Piecewise regression analysis, employed to identify the trend in the females, indicate an increase in size until the early 1900s and rapid decrease thereafter. Results suggest differential environmental pressures acting on this particular aspect of the skeleton among males and females.

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