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

Shape as a predictor of intermembral index


Biomedical Sciences, Grand Valley State University

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Researchers often attempt to use limb proportions to ascertain the locomotor repertoires of fossil hominins, but this approach can be problematic as few skeletons in the fossil record preserve both a full fore- and hindlimb. Consequently, estimates of full limb lengths are typically associated with substantial error. More frequently, the fossil record yields fragmentary remains of proximal and distal articular regions, but shape is sometimes considered to be less useful than indices for functional analyses. This study tests the hypothesis that the shape covariance between upper and lower limb elements is a good predictor of intermembral index, a more typical metric used in functional analyses.

Three-dimensional landmarks were collected on proximal and distal upper and lower limb elements of extant great apes and humans. Two-block partial least squares analyses were used to examine covariation between forelimb and hindlimb elements in these primates, and mean scores for each taxon were regressed against intermembral index to assess the correlation between these metrics. Results indicated that there is a high degree of covariation between fore- and hindlimb segments in the mixed species sample, particularly in the proximal ulna, distal humerus, and proximal/distal femur, and that shape covariation is significantly correlated with intermembral indices. Posthoc tests of the relationship between intermembral index and PC scores based on a single segment were statistically insignificant.

This work is funded by: NSF IIS 11-16921, NSF DDI 0333415 and WG 7516.

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