Department of Anthropology, Rutgers, The State University of New Jersey
March 27, 2015 8:30, Grand Ballroom A/B
Attempts to demonstrate the widely hypothesized relationship between food mechanical properties (FMPs) and jaw morphology have proven inconclusive. The temporomandibular joint is loaded during mastication, and the trabecular structure of the mandibular condyle may reflect differences in dietary FMPs in non-human primates. The relationship between FMPs and measures of trabecular architecture was tested using a sample (N = 8) of extant primate mandibles. Each mandible was scanned using high-resolution X-ray computed tomography (HRXCT). A 30-pixel cubic volume of interest from the center of the mandibular condyle was selected using ImageJ and analyzed with Quant3D. Bone volume fraction (BV/TV) and degree of anisotropy (DA) were calculated for each volume of interest. Values for maximum, median, and weighted mean toughness (R) of foods eaten by each species were taken from the literature.
Results of regressions of BV/TV and DA against toughness yielded no significant results, although the available sample is small. For BV/TV, median toughness most closely approached significance (R2 = 0.16, p = 0.18). Maximum toughness, which may represent the selective pressures associated with fallback foods, had no effect (R2 = -0.11, p = 0.6). Previous work suggested that BV/TV has a significant relationship with average daily time spent feeding. Thus, the lack of a relationship between BV/TV and FMPs suggests that repetitive loading of the jaw through mastication may be a more important driver of trabecular structure in the mandibular condyle.
Funding was provided by the Center for Human Evolutionary Studies, Rutgers, The State University of New Jersey.