Biomechanics of the primate craniofacial skeleton and its relevance to human evolution

Since J.T. Robinson's pioneering dietary interpretations of facial morphology in australopiths, studies on biomechanics of skulls have been reshaping our understanding of human evolution. Hypotheses concerning function and evolution in early human forms can be developed and tested through various theoretical and experimental biomechanical approaches, such as mechanical design modeling, geometric analysis, in vivo and in vitro strain gage experiments, and Finite Element Analysis (FEA). As an engineering technique used to analyze how objects of complex design resist load, FEA is particularly useful in examining biomechanics of craniofacial skeletons. Our recent discovery that elastic properties of cortical bones of craniofacial skeletons in closely related species demonstrate similar patterns of variation has allowed the precise extension of FEA to fossils. With Finite Element skull models from both extant and fossil primate species, we are able to investigate global synchronous stress and strain patterns in craniofacial skeletons, examine how they structurally adapt to resisting stress during mastication and other activities, and draw biologically meaningful information on mechanical advantages and evolutionary processes of various features in facial skeletons, e.g., anterior pillar in robust australopiths. Supported by National Science Foundation HOMINID grants 0725183 and MEDCEN 23750.