1Anthropology, Indiana University Bloomington, 2Radiology, University of Pennsylvania School of Medicine
Saturday All day, Park Concourse
Three hypotheses have prevailed in anthropology as the driving force of increased encephalization in primates: tool use, sociality and frugivory. Frugivory has been specifically targeted as a behavioral correlate with brain size as the temporal and spatial specificity of ripe fruit presumably requires the use of mental maps and is calorically better suited for a large, energetically expensive brain. For Hominins, fossilized endocranial surfaces provide the most direct evidence of brain evolution; yet endocasts may reflect only a fraction of the actual variation in brain anatomy. In the present study non-rigid deformation techniques were used to quantify localized variation in endocranial morphology across 19 non-human primate specimens using CT scans from the Open Research Scan Archive. Behavioral data on the percentage of fruit in each species diet was extracted from the literature. Correlations were calculated between these behavioral variables and the degree of localized distortion required to morph each species’ endocranial form into a common atlas (Pan troglodytes). Maps of the endocranial surface illustrating these correlations on a voxel-by-voxel basis suggest that frugivory may be specifically associated with endocranial shape in the following areas: rostral prefrontal, lateral cerebellum and inferior temporal. These results suggest that it might be possible to infer level of frugivory in the primate fossil record from endocasts.
Thanks to NSF for funding ORSA