Diet, dietary adaptations and feeding biomechanics in Australopithecus africanus

Abstract

Australopithecus africanus is an early hominin (i.e., human relative) believed to exhibit stress‐reducing adaptations in its craniofacial skeleton that may be related to the consumption of resistant food items using its premolar teeth. Finite element analyses simulating molar and premolar biting tested the hypothesis that the cranium of A. africanus is structurally more rigid than that of Macaca fascicularis, an Old World monkey that lacks derived australopith facial features. Finite element models of crania of these species were subjected to isometrically scaled loads, permitting a direct comparison of strain magnitudes. Moreover, strain energy in the models was compared after results were scaled to account for differences in bone volume and muscle forces. Results indicate that strains in certain midfacial skeletal regions are higher in M. fascicularis than in A. africanus, and that the A. africanus cranium is, overall, more rigid than that of M. fascicularis during premolar biting. This is consistent with the hypothesis that this hominin may have periodically consumed large, hard food items. However, the strain energy data suggest that the A. africanus cranium is marginally less rigid than that of the macaque during molar biting, raising the possibility that results are being influenced by the allometric scaling of cranial cortical bone thickness. Supported by NSF BCS 0725126.