Testing the genetic impact on the internal and external shape of teeth in non-human primates

Teeth provide information about the behavior, diet and health of a species. Due to these unique characteristics, dental studies have provided much information about past human and non-human primate (NHP) populations. In addition to the information about diet, behavior and health, teeth’s external morphology (shape) has been extensively analyzed in studies of lineage evolution and population relatedness. These studies rest on the idea that tooth development and resulting tooth morphology are under strong genetic control. However, morphological variation of teeth is high, and for many dental morphological traits the assumption of strong genetic control remains untested. This study advances knowledge about external and internal tooth morphology using non-invasive techniques in primate skeletal collections. The project supports students and scholars at different stages (postdoctoral, graduate and undergraduate students), and includes outreach activities directed to K-12 students in Puerto Rico and New York. Leveraging partnerships between the local clinical community and the University of Arkansas’ Predental Studies Program, this project also benefits society by providing research training and professional development opportunities to aspiring dentists. Analyses that infer evolutionary relatedness assume that dental traits faithfully relay genetic lineage information. But this assumption has yet to be empirically tested in many dental morphological traits. This study measures variation at the outer enamel surface, enamel-dentine junction, root, and pulp chamber in two NHP (M. mulatta, S. fuscicollis; N=550). Using paired microCT and pedigree data, this project takes a quantitative genetic approach to answer the following questions: (1) To what degree is dental morphometric variation (across distinct teeth and tissues) influenced by genes?; (2) What environmental factors impact tooth form throughout development?; (3) To what degree are tooth characters genetically correlated (influenced by the same genes)?; and (4) Does dental genetic architecture differ across taxa? By generating novel heritability, evolvability, and genetic correlation estimates, this project provides insights into the driving mechanisms of dental variation and how genes are recruited throughout development to influence distinct tooth structures. This information is essential to ground truthing the use of teeth for reconstructing evolutionary processes and experiences of stress and illness. The study is innovative in its incorporation of internal morphology, the use of non-destructive techniques, and its detailed examination of distinct moments in the development of internal and external dental morphology. The study contributes over 1,000 high-resolution scans and 3D surface models of skulls and teeth, extending curation of analyzed skeletal collections and enhancing teaching and research infrastructure through open-access digital archives. This project is jointly funded by the Biological Anthropology Program, the Established Program to Stimulate Competitive Research (EPSCoR), and the SBE Postdoctoral Fellowships. 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.