An assessment of dietary adaptations and mandibular morphology in non-human primates, as comparative models for early hominins.

This thesis examines the association between diet and the mandibular morphology in non-human primates as a model for understanding the morphology present in hominins. The traditional explanations of the morphological differences present in Paranthropus and Australopithecus have been challenged due to revised interpretations of the mandibular morphology, and the application of stable carbon isotopes and dental microwear texture analysis, which have resulted in a reassessment of the relationship between diet and masticatory morphology. The main aim was to explore the relationship between diet and mandibular/ dental morphology, whereby diet was analysed using a series of different diet classifications. Mandibular and dental traits were measured on a sample that included both extant non-human primate taxa (n = 37) and extinct hominin taxa (n = 6). The non-human primate species represent a diversity of dietary preferences, habitats and body sizes, while the hominin sample includes species from Paranthropus, Australopithecus and early Homo. Morphological differences were identified between consumers of different diets, including between consumers of hard and tough foods. The strength of the association between diet and morphology was influenced by how diet was classified, with the more refined dietary classification techniques consistently and more successfully identifying morphological differences. Body size differences were also identified. Results comparing the hominins to non-human primates of known-diet indicate that hominins were likely to have consumed quite varied (omnivorous) diets. The results also highlight how unique the hominin corpus robusticity is, whereby it is beyond the range of the extant non-human primates, thus diet interpretations in relation to extreme robusticity remain elusive. While diet is not the only variable to contribute to masticatory form, this research demonstrates that it has a measurable influence on mandibular morphology. This research therefore offers a new perspective addressing the association between diet and morphology, providing additional evidence comparing hominin morphology to that of the non-human primates. This study contributes to an area of active research in palaeoanthropology, and forms a basis from which additional studies can proceed.