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

Secular change in the femur


1Department of Anthropology, Texas State University, 2Department of Anthropology, University of California Santa Cruz

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Secular changes in skeletal morphology have the potential to impact the validity of methods used to develop an accurate biological profile and interpret activity patterns. This study examines secular changes in femur morphology of modern Americans using measurements from 962 adults with birthdates ranging from the 1840s to the 1990s. Regression analysis was used to examine the correlations and partial correlations between variables.

Results indicate that the femur has increased in length, decreased in robusticity, and the midshaft diaphyseal shape has changed from relatively circular to anteroposteriorly (AP) elongated due to a decrease in the mediolateral (ML) dimension. Femur head diameter, midshaft AP diameter, and subtrochanteric shape have not changed significantly. Nonsiginficant interactions between age and the diaphyseal variables indicate that age related expansion of the diaphysis is not the cause for the observed changes.

The femur morphology of modern Americans reflects the combination of changes in stature, body build, and activity levels that have taken place over the past one and a half centuries. There is a complex relationship between the diaphysis, total femur structure, and mechanical loading, with ML dimensions of the femoral midshaft being more sensitive to the level of mechanical loading than the AP dimension in Americans. Since most methods for estimating biological characteristics from the femur are based on nineteenth century skeletal collections, it is crucial that anthropologists understand how these secular changes may affect the interpretation of sex, stature, ancestry, and activity patterns in modern Americans.

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