1Department of Anthropology, The Pennsylvania State University, University Park, PA, 2UMR 7194 CNRS, Département de Préhistoire, Muséum national d'histoire naturelle, Paris, France
Thursday 11:30-11:45, Ballroom B
Both external and internal brain anatomical asymmetries have been shown not to be unique to humans. In 1973, Groves and Humphrey suggested that facial directional asymmetry (DA) could be indicative of asymmetric function in eastern gorilla’s brain, whether the facial asymmetry was directly related to anatomical asymmetry of the cerebral hemispheres or the consequence of asymmetrical chewing behavior. Here, we quantify the asymmetry of the middle and lower facial skeleton of adult eastern lowland gorillas (Gorilla beringei graueri) to determine the presence or absence of directional asymmetry. These results are compared with those obtained by Balzeau and Gilissen (2010) on brain anatomical asymmetries for the same specimens. Three-dimensional landmark coordinates were recorded on CT images of 32 G. beringei graueri. Using two different methods, namely Procrustes ANOVA and Euclidian distance matrix analysis, our results suggest the presence of significant fluctuating asymmetry and the absence of significant DA in the facial skeleton of G. beringei graueri. A negative correlation was found between the direction (left-right) of middle and lower face asymmetries. We also found an association between brain anatomical and facial asymmetries for the supero-inferior and antero-posterior dimensions. That is, the same side of the brain and face was more superiorly or inferiorly projected with even proportions for the left and right sides, while the right side of the brain and face was more often anteriorly projected than the left side. These results support previous reports of a relationship between brain and facial anatomical asymmetries in G. beringei graueri.
Partially funded by: R01DE018500; R01DE016886; EU FP6 “Paul Broca II, The evolution of cerebral asymmetry in Homo sapiens”