Sexual dimorphism in the craniofacial form of North American juveniles of European descent
Gonzalez, Richard Alexander
MetadataShow full item record
This dissertation identifies metric trends associated with sex differences in the growth and development of the human craniofacial skeleton. Lateral cephalometric radiographs housed at the University of Michigan School of Dentistry were randomly selected to create a cross-sectional sample. The sample size consists of 598 manually traced cephalometric radiographs representing juveniles ages 5-16. In each tracing, eight craniometric landmarks were identified. From these landmarks, 37 linear and angular dimensions were measured. Metric data collected from this sample were subjected to a multivariate canonical discriminant function analysis to identify sex differences in human craniofacial growth. The results of this investigation demonstrate the existence of sexual dimorphism in the growth of the human craniofacial complex. Sex differences are primarily allometric and derive from heterochronic influences. The pattern of sexual dimorphism presented in this study is the product of an early culmination of female craniofacial growth and of an extension of male craniofacial growth. The development of craniofacial sexual dimorphism in humans derives from two ontogenetic events. The first ontogenetic event takes place during the juvenile period, which begins with the eruption of the first permanent molar and ends with the eruption of the second permanent molar. During this period, sex differences are most evident in the neurocranium. Sex differences in this region primarily derive from growth differences in the brain. As a result, males tend to have a longer and taller neurocranium. The second ontogenetic event takes place during puberty, which begins with the eruption of the xi second permanent molar. This event marks a transition from advanced female growth to advanced male growth. At this period of development, secondary sexual characteristics develop in the male face. The identification of sex differences in craniofacial growth facilitates the development of classification models for sex identification in unidentified juvenile remains. Sex identification in the craniofacial skeleton of juveniles ages 5-16 ranges from 71-90% accuracy. The reliability of sex identification depends on stage of development and developmental trends. Therefore, the results of this study suggest that measurements from the entire craniofacial skeleton must be used in order to derive accurate predictive models for sex identification.