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

Environmental Plasticity of Intralimb Indices


Applied Forensic Sciences, Mercyhurst University

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Many studies have reported that human distal limb elements (i.e., tibiae and radii) display greater secular changes and positive allometry with stature than their proximal counterparts. This suggests that distal limb elements may be more environmentally plastic than proximal elements. If true, samples subjected to improved living conditions should exhibit a systematic change in intralimb indices.

This study tested the above hypothesis using osteometric data collected from five geographically different and temporally diverse population groups: recent American Whites, recent Portuguese, medieval Nubians, Point Hope Arctic Native Americans and Plains Native Americans. Within each population group, long bone lengths were collected from two samples exposed to contrasting living conditions (n total = 318). Relative living conditions were evaluated using previously published demographic, socioeconomic, and health information. Crural and brachial indices were calculated and compared across each (within-population) paired sample to determine whether there was a directional change in intralimb indices with relative living condition. Results showed no consistent trend in male or female intralimb indices across the sample comparisons. When populations were pooled, males and females displayed greater positive allometry in the distal limb elements relative to proximal elements. Within populations, however, relationships between distal and proximal elements did not significantly differ from isometry. These results demonstrate that the response of proximal and distal elements to living conditions may vary from those patterns that have been published, and that further investigation is needed into the effects that specific extrinsic and intrinsic variables may have on limb lengths and proportions.

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