Presenter(s): Andrea Quintanilla—Anthropology
Faculty Mentor(s): Stephen Frost, Evan Simons
Session: Prerecorded Poster Presentation
Primate cranial shape in relation to age, sex and taxonomy is a growing topic of research, with large- bodied Old World monkeys being among the most studied using geometric morphometrics (GM) and used as models for human cranial shape variation . Ontogenetic changes to skull shape from juveniles to adults are well studied, but those that occur during adulthood are less well known: a twenty-year old is still an adult, but their skull could differ in shape compared to that of a sixty-year old . In this project, we used GM and multivariate analyses to observe changes of cranial shape that occur with post-adult aging . Forty-five 3D landmarks were collected with a Microscribe 3DX digitizer on a sample of 347 wild-collected baboon (Genus Papio) crania, and subjected to generalized Procrustes analysis using the Geomorph package in Rstudio; this superimposes the data and standardizes geometric size, but leaves shape differences . The resulting Procrustes shape coordinates were adjusted for size and sex with multivariate regression analysis to mitigate the effects of allometry and dimorphism . These adjusted coordinates were then regressed against upper third molar wear stage as a proxy for age, using multivariate tests for significance . Principal components analysis was used to summarize the resulting shape space . Results demonstrated that there is a significant effect of molar wear stage on cranial shape, even after accounting for size and sex differences, but it is a subtle effect that accounts for approximately 1% of shape variance . In the future, we will investigate causes of this shape change .