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

Morphological variation of modern human browridges


Department of Applied Forensic Sciences, Mercyhurst University

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The browridge, or supraorbital torus, is a distinct craniofacial feature which is found throughout the human lineage in a variety of forms. The browridge remains evident in modern humans and is one of the primary discrete cranial traits used in sex estimation methods. Descriptions of browridge morphology and sexual dimorphism in modern humans are commonly limited to discussions and scoring methods based on degree of projection. In this study, 3D surface scans were collected from 669 crania from geographically and temporally diverse populations, and shape analyses were performed on the isolated browridge regions. The diverse browridge forms observed across six populations and thirteen samples are presented and discussed in terms of geographic patterns and sexual differences.

Although browridge projection remained the most sexually dimorphic feature, geometric morphometric analyses (GPA, PCA) revealed a number of other morphological variations not traditionally discussed in the anthropological literature. These variations include the degree of lateral extension of the browridge, the relative projection of the browridge at the midline in comparison to the supraorbital region (i.e., continuity/discontinuity of browridge projection at glabella), the degree to which the browridge arches over and diverges from the supraorbital margin, the relative angle of brow projection and the radius of browridge curvature. Knowledge of such morphological diversity in the browridge has important implications, especially with regard to ancestry and sex estimation methods. In addition, a better understanding of variations in browridge form may provide insight into the adaptive functions of this trait.

This study was funded by National Science Foundation DDIG, grant number BCS-1061313, and Sigma Xi GIAR, grant number G20101015155040.

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