My project seeks to understand the anatomy of the australopithecine mouth and its evolutionary significance. The Australopithecine's "hominin" status is based on their uncontested bipedality (with some retained arboreality). The genus existed in Africa for over 2 million years, during which time there were no major changes in their cranial capacity. As these two extremely important features of human evolution were relatively conserved in australopithecines, my project asks whether we can observe selective pressures acting on other critical attributes. Specifically, it investigates what anatomical changes can be detected in their facial-dental structure, what constitutes an australopithecine mouth, why they had the mouth they did, and its contribution to the longevity of the genus. The novelty of this work lies in employing recent advances in geometric morphometric analysis to explore the craniofacial architecture and morphological variation in the entire oral cavity. Variation and correlations are examined in available fossil material and interpreted in light of reconstructions and anatomical knowledge of extant primates. This can be best examined now there is a larger number of Australopithecus specimens and therefore the ability to track changes across evolutionary time.
The initial question for my investigation is: What determines the size and shape of the mouth? This involves looking at the individual elements and their integration across primates: individual teeth, their spacing, the palate, maxilla, mandible, and temporo-mandibular joint. I ask two central questions regarding australopithecine morphology: What variation exists? What correlates exist? If the variation is greater than that observed in other primate taxa could it reflect extreme selection pressures based on a fluctuating environment, diet, life history, inter/intragroup competition, sexual selection? I hope to demonstrate that the form of the mouth and bipedal posture are inextricably linked. To do this, I will record the morphological variation in the South African species of Australopithecus, and test it against data collected for extant species (Homo sapiens, Pan paniscus, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus and Hylobates). These species will be used to build a model for understanding the adaptive significance of morphological characteristics and can provide possible behavioural, ontogenetic and other explanations for anatomical variation. The australopithecine specimens studied are held at the Transvaal Museum, and University of Witwatersrand, South Africa.