Doctoral Dissertation Improvement: Dental Microwear of Pliocene Bovids from East African Hominin Sites: Implications for Paleoenvironmental Dynamics and Human Evolution

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Many researchers have suggested that Pliocene climate change was a motive force for human evolution. The basic idea was that a shift toward drier, more open settings led to adaptations for bipedality and the consumption of savanna resources, including large grazing mammals. However, more recent paleoenvironmental reconstructions suggest that Pliocene hominins occupied more variable or mosaic habitats including both open and closed settings. While many techniques have been used to refine our understanding of the paleoenvironments of eastern Africa, these have not led to consensus reconstructions. This project will test competing hypotheses for the paleoenvironments of four sites associated with Australopithecus anamensis and A. afarensis by bringing a new, independent dataset for the inference of diet and by extension, habitats, of actual individuals in the days preceding their death. This study uses dental microwear texture analysis to reconstruct ratios of graze to browse in the diet, and therefore ecological contexts, of fossil bovids from Kanapoi (8 genera), Allia Bay (7 genera), Laetoli (8 genera) and Hadar (9 genera). This project will reconstruct the paleoenvironments of these four important early hominin sites and how ecological settings may have changed over the temporal spans of the hominins that lived there. Intellectual Merit: A large database of microwear textures for both extant and fossil bovids will be generated, and will provide a substantial comparative collection for future research. It will also serve as an important test of taxonomic uniformitarianism, which is often assumed in the use of faunal assemblages as paleoenvironmental proxies. In addition, since evolutionary changes in A. anamensis and A. afarensis are widely considered to be adaptations to shifting paleohabitats, the improved reconstructions resulting from this study will have important implications for understanding the relationship between environmental change and human evolution in eastern Africa during the Pliocene. The broader impacts of this study include establishing a doctoral dissertation research program for a female graduate student from an underserved, EPSCoR state and provide a research assistantship to an undergraduate through the University of Arkansas Honors College-Environmental Dynamics Research Mentoring Experience for Students (HERMES) program. It will provide both students with training in data collection techniques and research methods.