Doctoral Dissertation Research: Understanding enamel hypoplasia in great apes of known life history

George Washington University, Washington DC

Investigators

Abstract

Much like tree rings provide a record of growth patterns related to past environmental conditions, teeth can preserve a record of physiological stress experienced during dental development. This doctoral dissertation project will use novel imaging and analytical methods to study stress-related dental defects in Virunga mountain gorillas for whom long-term behavioral, health, and climate data are available. The ability to link specific dental defects to specific life events will improve our understanding of the complex interplay among ecological, social, and physiological stressors in both extant great apes and fossil hominins. The project will support student mentoring and training in STEM fields as well as collaborations and conservation efforts at the research site. Teeth are important to studies of health and development because they provide a permanent and detailed record of their absolute chronological growth. Enamel hypoplasias manifest as grooves on the tooth surface when growth is disrupted by stressors such as undernutrition and disease. Hypoplastic defects are usually scored by low-power enamel surface observation, and the boundary between normal and abnormal morphology has never been quantitatively defined in great apes. This project employs quantitative criteria to diagnose defects, and establishes a minimum threshold for determining what is a defect versus what is within the bounds of normal variation. Aims include: (1) determining defect presence quantitatively, and testing for differences in defect prevalence and morphology among mountain gorillas and other great apes; (2) analyzing microanatomical parameters of crown growth to determine which factors influence variation in defect morphology among great apes; and (3) testing correspondence between defect timing and stressful events (e.g. injury, disease, intergroup interactions) in the recorded history of individual mountain gorillas to produce the first data on enamel hypoplasia etiology in wild gorillas. By assessing the relationships between defect morphology, microanatomical parameters of enamel growth, and documented stressors in associated life history records, the proposed research will deepen our understanding of factors that underlie differences in defect expression among great apes, and thus improve our ability to more confidently interpret enamel defects in paleoanthropological contexts.