Doctoral Dissertation Research: Abrasive foods, tooth size, and enamel thickness in primates

The consumption of tough, abrasive foods may have contributed to key changes in the teeth of our earliest human ancestors. Researchers have proposed that the ingestion of particles that are abrasive to tooth enamel was an important force structuring dental traits during human evolution, including thicker enamel and larger tooth size. A debate exists regarding the type of abrasive material that would have been the most important for understanding the evolution of human teeth. This doctoral dissertation research project investigates whether tooth size and enamel thickness vary with the 1) ingestion of abrasive particles, and (2) how well primates chew their food in the wild. This project trains students from backgrounds underrepresented in STEM in field and lab methods, some leading to independent honors projects, and contributes K-12 and museum educational outreach. The project further contributes to capacity building at a long-term primate field station in a UNESCO World Heritage Site. The long-term objective of this research is to inform hypotheses that pivot around form-functional relationships between primate foraging behaviors and dental traits, an essential task for inferring behavior in the human fossil record. The investigators (i) differentiate and quantify phytoliths and grit in the diets of the monkeys and compare this variation to (ii) variation in fecal particulate size (a metric of chewing performance); and (iii) variation in tooth size and enamel thickness collected from population-specific skeletal collections. This project leverages established and emerging techniques in primate dental ecology to unravel a long-standing puzzle. Molar size and enamel thickness are traits of enduring importance to paleoanthropologists, being central to phylogenetic reconstructions and dietary inference, but with little functional consensus due to the uncertain and potentially confounding effects of abrasive material in the diet. To resolve this puzzle, this investigation collects systematic data on the siliceous composition of primate diets and uncovers the relationships between this composition, dental morphological traits, and chewing performance in living primates in the wild. 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.