Dental features are frequently used in species diagnoses and phylogenetic reconstructions of hominins (humans and their fossil relatives). The study of teeth has also played an important role in reconstructing hominin diets, as well as biological relationships among recent human populations. However, dental variation is the result of not only phylogenetic and functional interactions, but also the developmental processes controlling tooth morphogenesis. Interestingly, the role of development on the morphological diversity in the hominin dentitions has generally been overlooked. Research by doctoral candidate Alejandra Ortiz (New York University), under the supervision of Dr. Shara Bailey, will investigate how development has shaped the evolution of hominin tooth forms. Specifically, this project will examine several dental traits drawn from a large sample of molars in order to explore the developmental basis of homology (defined as similarity due to common ancestry) and determine patterns of developmental integration in members of our lineage. By examining trait homology and independence, this integrative approach will attempt to identify dental features of high phylogenetic valence and help solve the long-standing problem in anthropology associated with the ambiguity of past hominin phylogenetic hypotheses. The use of developmental information will also contribute to the taxonomic identification of unknown hominin specimens.
High-resolution micro-computed tomography (microCT) will be used to visualize the internal and external surface of teeth at the enamel-dentine junction and outer enamel surface, respectively. This research will be undertaken in approximately 500 molars assigned to a number of species from the genera Pan, Australopithecus, Paranthropus and Homo. Data will be analyzed both qualitatively and quantitatively via visual assessments, three-dimensional geometric morphometrics, and linear and area measurements.
This project will promote international collaboration within the scientific community and provide training opportunities for undergraduate students. Support for this project will encourage diversity within the biological sciences, as the co-PI is a female from an underrepresented group in science. Importantly, this project will contribute to the development of a virtual collection of microCT scans, the use of which will minimize data collection errors and limit the manipulation of fragile fossil material. These microCT scans will be available for public access according to individual agreements with participating museums. Furthermore, metric data derived from this project will be made freely available online. Since questions related to human evolution are of broad public interest, results of this study will be presented at academic conferences, as well as disseminated in technical and popular publications. This project will seek to create linkages among multiple fields of research, including dental anthropology, paleoanthropology, systematics and evolutionary developmental biology.
