Abstract # 211:

Scheduled for Monday, August 28, 2017 01:30 PM-01:45 PM: (Grand Ballroom) Oral Presentation


FACTORS INFLUENCING DEVELOPMENTAL ENAMEL DEFECTS UNDERSTOOD TO RECORD STRESS IN WILD GREAT APES

K. McGrath1, D. Guatelli-Steinberg2, S. El Zaatari3, K. Arbenz-Smith1, D. J. Reid1, M. R. Cranfield4, T. S. Stoinski5, T. G. Bromage6, A. Mudakikwa7 and S. C. McFarlin1,8
1The George Washington University, Center for the Advanced Study of Human Paleobiology, 800 22nd St NW, Ste 6000, WASHINGTON, D.C. 20052, USA, 2Department of Anthropology, The Ohio State University, 3Paleoanthropology, Senckenberg Center for Human Evolution and Paleoenvironment, Universität Tübingen, 4Mountain Gorilla Veterinary Project & Baltimore Zoo, 5Dian Fossey Gorilla Fund International & Zoo Atlanta, 6Department of Biomaterials and Biomimetics, New York University College of Dentistry, 7Department of Tourism and Conservation, Rwanda Development Board, 8Division of Mammals, National Museum of Natural History, Smithsonian Institution.
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Linear enamel hypoplasia (LEH) is a common developmental defect on the outer tooth surface, and is associated with stressors like malnutrition or illness. We recently showed that LEH are more common in mountain gorillas than previously recognized, but they are significantly shallower than in other apes (p=<0.001). While shallow defects are assumed to reflect reduced stress severity, enamel geometry may also influence defect morphology. In canine histologic sections of wild Virunga mountain gorillas (N=3) and other great apes (N=6), we measured the angle with which enamel growth increments approach the outer tooth surface. We found that mountain gorillas have significantly shallower striae angles than other apes (ANOVA, p=0.027), which may reflect faster enamel secretion rates and contribute to comparatively shallow defects. Within mountain gorillas, we compared LEH depth among naturally accumulated skeletons collected by Dian Fossey (Smithsonian’s NMNH; 1968-1974) and those collected recently (Mountain Gorilla Skeletal Project, Rwanda; post-1996). The gorillas collected by Fossey (N=17 defects; mean depth=25.8 μ) have deeper defects than those that lived more recently (N=79 defects; mean depth=19.6 μ; Welch’s t-test, p=0.059). These results suggest that variation in defect expression among great ape teeth likely reflects the combined influence of enamel geometry and stress. Future studies incorporating associated records will provide the first data on LEH etiology in gorillas. NSF (IGERT 0801634; BCS 0852866, 0964944, 1520221,1613626), The Leakey Foundation, NGS (8486-08)