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

Secular Changes in Robusticity of Limb Bones in Americans


Department of Applied Forensic Sciences, Mercyhurst University

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Secular changes in limb bone lengths over time have been studied extensively by anthropologists over the last few decades. Curiously, secular changes in skeletal robusticity have been largely ignored; instead, robusticity is generally studied to infer the level of activity in prehistoric populations. Over the last two hundred years, the trend towards a more sedentary lifestyle suggests significant changes could have occurred.

This study analyzed several measurements taken from the femur, tibia and humerus collected from the Terry Collection and the Forensic Data Bank to bridge the gap in our understanding of secular changes in robusticity. The sample was subdivided based on sex and ancestry. All individuals were born between 1828 and 1995. Long bone lengths, breadths, and robusticity indices were regressed on birth year using loess curves. Inflection points of 1900 or 1940 were discerned in the groups and used with parametric and nonparametric tests to determine statistical significance. All p values were adjusted for multiple comparisons.

Nineteen of the 48 comparisons showed significant secular changes (p < 0.02). All limb bones increased in length over time, with the exception of the white male humerus. Also, all four groups show a decrease in lower limb bone breadths, which, coupled with an increase in length, decreased robusticity. Concurrently, the shorter humerus in white males and the increase in the other groups’ epiphyseal breadths increased upper limb robusticity. Of the four groups analyzed, black males demonstrated the greatest secular changes in robusticity.

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