Announcing the Final Examination of Ms. Catherine Shipman for the degree of Master of Arts in Anthropology
Sex determination of unknown individuals is one of the primary goals of biological anthropologists. The adult skull is often used in sex estimation, due to its marked traits of sexual dimorphism. However, estimating skeletal sex from juvenile remains is controversial due to the uncertainty surrounding the presence of sexual dimorphism prior to sexual maturity. The aim of this study was to apply geometric morphometric shape analysis to non-adult skulls to explore patterns of sexual dimorphism during ontogeny and to identify the most dimorphic region(s) of the skull. Computed tomographic (CT) scans were acquired from the New Mexico Decedent Image Database comprising 101 male and 99 female skulls ranging in age between birth and twenty-one years. Three-dimensional coordinates (42 landmarks and 290 curve semilandmarks) were placed on surface models generated from the CT scan and four landmark configurations were evaluated: the viscerocranium, mandible, frontal bone, and mastoids. Generalized Procrustes superimposition, principal component analysis, and discriminant function analysis were applied to all four configurations independently. In line with previous studies, results demonstrated a low degree of sexual dimorphism and poor cross-validated classification accuracy in individuals less than 13 years of age, with the highest accuracy in the mandible and the viscerocranium. Using these methods the shape similarities found between the sexes prior to 13 years of age prevent consideration of the craniofacial bones as a sex indicator in the early stages of development but support its use in older adolescent individuals, especially when using multiple regions of the face.
Committee in Charge:
Dr. Sarah Freidline, Chair
Dr. John Schultz, co-chair
Dr. Sandra Wheeler
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