Department of Anthropology, Pennsylvania State University
Thursday 11:45-12:00, Ballroom B
Despite being phenotypically distinct, hominoids have a common pattern of cranial integration. That is, coordinated variation among developmentally and/or functionally related cranial components is similar among hominoid species. While there have been several studies on morphological integration in the cranium, few have focused solely on the hominoid mandible. A better understanding of mandibular integration patterns can provide insight on factors that generate morphological constraints in the hominoid skull. This study examines ontogenetic integration in 140 sub-adult and adult humans, chimpanzees and bonobos to assess how integration patterns in the mandible compare to those of the cranium. A total of 29 3D landmarks were collected on the entire mandible and subsequently divided into developmental modules (alveolar region and ramus) to examine integration. Procrustes-based geometric morphometrics and two-block partial least squares analysis were conducted to quantify and examine integration patterns. PLS1, which accounts for 66% of the total covariance in the dataset, shows that Pan and Homo have a common pattern of integration, with the juvenile chimpanzees and bonobos clustering with the adult humans. Shape changes show humans to have a short alveolar region associated with a short and broad ramus, compared to an elongated alveolar and tall ramus in Pan. PLS2 (16.2%) separates humans from Pan, and accounts for shape changes mainly along the symphysis and inclination of the ramus. Overall results suggest that morphological integration in the cranium and mandible is similar among these taxa; however, species-specific integration patterns are more distinct in the mandible than in the cranium.
Funding sources: Marie-Curie (“EVAN”) Action grant MRTN-CT-2005-019564; NIH/NIDCR grant #R01-DE018500