NSF Award
2018779
The diverse shapes of cheek teeth are broadly reflective of the diets that living primates and their fossil relatives consumed. Yet teeth stand apart from other biological structures in that they do not have the capacity to remodel or repair themselves and instead must continue to perform their chewing function, even as they wear down. This is an issue exacerbated in long-lived animals such as primates. This project investigates how tooth wear affects food break-down functionality in two primate taxonomic groups with highly contrasting teeth?apes and Old World monkeys?and explores what these patterns reveal about the dietary evolution and competition between them. Data for this work will be collected via microCT scanning of museum specimens and made accessible via a web-based repository open to researchers, educators, and the general public, improving access and educational opportunity, particularly for examining rare fossils. This research will enhance existing methodologies through development of new, freely available software for the scientific community and promote scientific communication with a conference session dedicated to this subject matter. Undergraduates will receive training in the scientific process and methods applicable to a wide range of STEM professions. Project findings will be publicly communicated through an exhibit that allows general audiences direct interaction with researchers and fossil primate specimens at the Duke Lemur Center, and through development of educational material for their youth summer science camps.<br/><br/>This project addresses the significant gap in scientific understanding of how cheek tooth shape changes as teeth wear and the attendant functional implications. Despite general acknowledgement that natural selection continues to operate on primate dentitions throughout their reproductive lives, even as teeth wear, the majority of primate feeding ecology investigations have focused on the initial pristine form of teeth. This focus has emerged from the methodological dependence on using identifiable and homologous features of tooth crowns, which are often highly modified or obliterated by wear, rendering worn teeth uninformative. The development of homology-free quantifications of occlusal surface geometry, known as dental topographic metrics, liberates researchers to extend comparisons across wear series and better characterize lifetime dental form-function associations. This research leverages these techniques to address how the divergent structural patterns of ape and Old World monkey (so called bilophodont) molars change with tooth wear to maintain and/or enhance features related to chewing efficiency and wear resistance. Living species with diverse dietary and feeding substrate preferences will be used in phylogenetically-informed comparisons incorporating dental topography, enamel thickness distribution, and tooth wear. This broad comparative sample will form the basis for the study of dental wear among well-sampled fossil anthropoids from 35 to 15 million years ago to inform both the dietary ecology of fossil taxa and evaluate the adaptive significance of bilophodont molars of monkeys compared to the primitive cusp pattern still observed in living apes. The results of this work will describe the lifetime functional effectiveness of bilophodont teeth and inform the observed success of the Old World monkey radiation compared to that of apes over the past 15 million years.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
