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

Temporal changes in Arikara femoral torsion


1Department of Anthropology, Texas State University, 2Forensic Anthropology Center at Texas State

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Femoral torsion is a biomechanically relevant parameter that can aid in reconstructing activity in past populations. This study investigates temporal trends from the mid-sixteenth century to early nineteenth century in femoral torsion among the Arikara, a Great Plains Native American tribe that had a mixed subsistence economy based on horticulture, gathering, hunting, and fishing. Torsional angle was assessed by direct measurement and by using the orientation of the maximum bending rigidity (theta) at subtrochanteric in 119 females and 165 males from three variants of the Arikara Coalescent tradition. Previous research supports significant temporal changes in Arikara long bone diaphyseal shape and strength among females associated with increases in workload necessary to produce surplus corps during the historic period. While there were no major changes in the types of activities conducted by the Arikara during the Coalescent tradition, there was an intensification of crop and hide production by females to increase output for trade. The results of this study show that asymmetry in femoral torsion increases dramatically from the protohistoric (mean asymmetry = 7°) to the early historic period (mean asymetry = 30°) among females. We hypothesize that the change in torsion angle may be associated with sitting posture. Specifically, the asymmetry in torsion may be related to females spending a substantial amount of time in a modified W-sitting posture that widens the base of support for the body and results in greater stability and comfort when sitting for long durations.

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