1Department of Archaeology, University of Sheffield, UK, 2Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon SK, Canada, 3Department of Cell and Developmental Biology, University College London, UK
Friday All day, Plaza Level
Accurately aging living and fossil primates is integral to human biology, palaeoanthropology, and related fields. The use of dental radiographic image data to estimate age in both living and skeletal primate samples is widespread. In humans, studies of dental development and aging are available for very large, aged samples. Importantly, interpopulation variation is also relatively well-represented. However, this is not the case for apes such as the chimpanzee. With few exceptions, dental age assessments in chimpanzees have been hindered by a reliance on wild-shot and thus un-aged samples (usually skeletal material), small and cross-sectional data sets, and unbalanced sex distributions. Such methodological problems limit accurate age assessments in living or skeletal chimpanzee samples, and may contribute to the large differences in estimated ages reported between captive and wild chimpanzee samples.
This study revisits published methods for dental age assessment in chimpanzees to develop more robust approaches to aging using dental development data. We use dental stage scores for the left permanent mandibular teeth in an aged sample (from 1 to 11 years) of 118 captive chimpanzees, and an unaged wildshot sample of 75 chimpanzees and 44 bonobos. Using bivariate and multivariate regression models of ordinal-scale tooth development stage data, we evaluate age estimates of the permanent dentition against known age, dental maturity score, and age estimates based on single-tooth (e.g., M1) assessments. Comparison of regression parameters indicate that teeth completing maturity at later ages (i.e., C and M3) can be excluded in age assessment because of greater developmental variability.