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

The role of masticatory strain in the phylogenetic utility of cranial datasets in papionin primates


1Department of Anatomy, AZCOM, Midwestern University, 2School of Human Evolution and Social Change, Arizona State University, 3School of Anthropology & Conservation, University of Kent

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Recent studies have suggested that the quantity of strain imposed upon a cranial region during mastication may affect the degree to which it reflects phylogeny among primate species. The homoiology hypothesis states that the plastic deformation and homoplasy experienced by high strain cranial regions should render them less phylogenetically informative than low strain regions. To test this hypothesis in the Papionini, the 3D morphology of two high strain cranial regions, the palatomaxilla and zygotemporal, were compared to that of a low strain region, the upper face, in 15 papionin species using landmark-based analyses. The sample was separated by sex, and each dataset subjected to Generalized Procrustes Analysis and Principal Components Analysis. PCs found to be significantly correlated with centroid size were excluded from the analysis, and a Mahalanobis distance matrix was generated of interspecific distances for each cranial region. A molecular distance matrix was calculated using published genetic data.

All three cranial datasets for each sex were found to be significantly correlated with molecular distances using a Mantel test. A Dow-Cheverud test revealed no significant differences between the degree to which the upper face reflected the molecular matrix compared to the palatomaxilla or zygotemporal. Thus, there is no statistical support for the homoiology hypothesis here, since the low strain regions do not reflect phylogeny significantly more reliably than high strain regions. This result corroborates findings from previous studies using linear cranial dimensions to reconstruct intergeneric relationships, and upholds the idea that the homoiology hypothesis is not supported among catarhine primates.

This research was funded by The Leakey Foundation.

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