This grant permits Dr. Hylander and his colleagues to study the effect of canine size on how animals chew. A detailed analysis of jaw movements and loading patterns will be conducted on 4 adult male and 4 adult female baboons to answer three related questions. During mastication, what is: (1) the influence of canine size (males vs. females) on jaw movements, (2) the influence of the mechanical properties of food on jaw movements, and (3) the relationship between loading and jaw movements. The investigators wish to focus particularly on the interaction of the three questions. To accomplish this they will analyze vertical, lateral and front.to.back jaw movements with a magnet sensing jaw.tracking system originally designed for humans. Loading patterns of the mandible will be analyzed by both strain gage and electromyograplhic techniques. One tgait which distinguishes human from other primates is the reduced size of our canine teeth and the functional significance of this, which is evident in the earliest humans, continues to be a crucial and much debated topic in paleoanthropology. This research is designed to test the hypothesis that canine reduction eliminates mechanical constraints on mandibular movements during mastication. The elimination of these constraints supposedly allows an increase in the sideway movement of the mandible during biting and thus increases the overall efficiency of mastication. This project will help to answer this question. The research is important because it will help to explicate the factors which underlie human development and led to the appearance of our own species.
