Meeting Abstract
The relationship between inertial properties and the scaling of oscillation frequency has been studied in locomotor but not in feeding systems. We estimated the moment of inertia of primate mandibles from CT scans. We hypothesized that if mandibular momentum plays an important role in chewing dynamics, accurate estimates of the rotational inertia of the mandible would improve the ability of simple models to predict the scaling of primate chewing frequencies. If this hypothesis was falsified, this would suggest that mass-related momentum effects are of negligible importance in the scaling of primate chewing frequency. We found that the rotational inertia of primate mandibles increases with jaw length across primates due to slight positive allometry of jaw mass to length, and to size-correlated changes in the distribution of jaw mass relative to a transverse axis through the center of mass. Positive allometry of the rotational inertia of primate mandibles lowers the predictive ability of the Spring Model, suggesting that scaling of primate chewing frequency is more strongly influenced by the dynamic properties of the jaw muscles and neural control than by scaling of inertial properties of the mandible. Differences in cycle period scaling between chewing and locomotion systems are suggestive of differing design criteria: displacement and force control are more important in the design of feeding systems and energetics and speed are more important in the design of locomotor systems.
