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


Investigating Sexual Dimorphism of the Mandible Using 3D Geometric Morphometrics

KATHLEEN A. HAUTHER and BEATRIX DUDZIK.

Anthropology, University of Tennessee

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Numerous studies of the human cranium have indicated that the skull is not always a reliable indicator of sexual dimorphism, yet far fewer publications have utilized the mandible to examine sex differences within modern populations. Available research of the modern human mandible shows that differences exist between sexes and ancestral groups (Berg, 2011 and Humphrey et al., 1999). This study examines the hypothesis that differing patterns of sexual dimorphism between modern American White, American Black and Thai samples can be identified by quantifying size and shape variables of the mandible using a geometric morphometric approach.

This paper examined mandibular data from American Whites and American Blacks from the William M. Bass Donated and Forensic Skeletal Collection at the University of Tennessee, Knoxville. In addition, mandibular data from the Khon Kaen University Anatomical Collection, Thailand was also included. Twenty three landmarks were digitized and recorded by both authors using a MicroScribe GT according to the methods outlined by Mckeown and Ousley (1999). Coordinate data was extracted and analyzed using MorphoJ software. All landmark data was scaled and rotated using Generalized Procrustes Analysis, and Principal Coordinate Analysis was performed on the extracted shape variables. Results indicate that patterns of sexual dimorphism based on mandibular dimensions differ between the sample populations utilized. The quantification of shape differences between males and females using geometric morphometrics indicates benefits for practitioners, in that a better understanding of patterns of variation is identified. Thus, results provide utility for anthropologists working within archaeological and forensic contexts.

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