Three Dimensional Comparisons Of Craniofacial Morphology And Growth Patterns In Neandertals And Modern Humans PDF Download

This project examines patterns of phenotypic integration in modern human cranial morphology using geometric morphometric methods. It is theoretically based in the functional paradigm of craniofacial growth and morphological integration. The hypotheses being addressed are: 1) cranial form is influenced by secular trends, sex, and phylogenetic history of the population and 2) integration patterns wherein the basicranium is the keystone feature best explains the relationships among in cranial modules. Geometric morphometric methods were used to collect and analyze three-dimensional coordinate data of 152 endocranial and ectocranial landmarks from 391 anatomically modern human crania. These crania are derived from temporally historic and recent groups in the United States spanning both sexes and across several ancestral groups. Landmark data were subjected to generalized Procrustes analysis and then areas of shape variation were identified via principal components analysis of shape coordinates. Discriminant function analysis and canonical variate analysis identified regions that can be used to separate groups. Temporal period, ancestry, and sex all have significant effects on mean shape. Age-at-death accounts for a small proportion of the total variation. Modern individuals have higher, narrower vaults with highly arched palates and historic individuals have short, wider vaults with shallower palates. The forehead, brow ridges, and cheek shape were closely associated with sexual dimorphism. Variation in both the vault and face allowed for separation of ancestral groups with concomitant inferior movement of the anterior basicranium in the median plane. Three major hypotheses of modularity were tested based on functional demands of cranial modules, functional-developmental fields, and the basicranium. Comparing covariance structures of partitions of landmark subsets revealed that the cranium is more integrated when considering functional demands of cranial components origins of cranial components and is less modular when considering developmental origins. Special sensory modules are the most independent units in the cranium. Depending on the definition of cranial modules, results may be quite different and not comparable across studies. This project integrates anthropology, evolutionary anatomy, and developmental biology. It makes a significant contribution to our understanding of integration patterns in the modern human cranium and highlights differences among theoretical frameworks of integration. The findings can be used for individual identification in medicolegal contexts and clinical applications for surgical treatment of craniofacial-related disorders and injuries. Future research will include examining patterns of morphological integration in non-human primates.