Considering the constrained lever model: Feeding biomechanics of OH 5 assessed using finite element analysis

Abstract

The craniofacial morphology of Paranthropus boisei exhibits a number of highly derived characteristics that have been argued to be functionally related to feeding. These features are hypothesized to either decrease structural stress, increase the mechanical advantage of the masticatory muscles, or both. But complications arise when the constrained lever model is considered. This study uses finite element analysis to test the hypothesis that the P. boisei cranium is structurally stronger and configured to more efficiently generate bite force than the crania of Pan troglodytes and Australopithecus africanus. To assess our analyses within the context of the constrained lever model of chewing biomechanics, joint reaction forces are also examined.A finite element model was created from a reconstruction of the OH 5 cranium. The model was assigned chimpanzee material properties, constrained at the TMJs and bite points, and subjected to scaled muscle forces derived from chimpanzees. Strains, bite forces and strain energy were recorded. The results were compared to those from FEA of other hominid crania. Results indicate the face of P. boisei is structurally strong and the extreme morphology of this species allows for the generation of high bite forces on posterior teeth without violating the constrained lever model.(NSF BCS 0725219, 0725183, 0725147, 0725141, 0725136, 0725126, 0725122, 0725078) and the EU FP6 Marie Curie Actions MRTN‐CT‐2005–019564 “EVAN”.