Biological anthropologists have a long-standing interest in the influence of diet and feeding on all aspects of primate biology, including primate evolution, behavior and morphology. Comparative studies of the structure of primate skulls and teeth, field studies on dietary selection and foraging behaviors, and laboratory studies on the dynamics of feeding in captive primates have all contributed significantly to this endeavor. However, these research programs have never been fully integrated, and assumptions inherent to each limit the strength of hypotheses linking diet and feeding to primate biology and adaptations. For example, an assumption of lab research is that feeding behaviors and jaw-muscle activity recorded in the lab accurately reflect those of wild primates feeding in their natural habitats. Likewise, when applying field work to questions about the evolution of primate feeding, it must be assumed that field observations are related to masticatory function as observed in the lab.
The goal of this study is to integrate multiple lab and field methods into a study of foraging in free-ranging mantled howling monkeys at Hacienda La Pacifica, Costa Rica. First, using new technology designed specifically for this project, electromyographic data will be recorded from their jaw muscles while these animals feed in their natural habitat. Second, the mechanical properties of the foods consumed during the recording period will be quantified. Third, tooth wear will be quantified immediately prior to and following the recording period. Finally, feeding and ranging behaviors of individuals will be collected during the recording period.
Data from this study will be used to demonstrate how primates use their jaw-muscles during feeding on their natural foods and to generate ecologically relevant hypotheses relating jaw-muscle function to jaw structure. The jaw-muscle activity data will also be correlated with food mechanical properties, feeding behaviors and the progression of tooth wear. More generally, the proposed research will be the first of its kind to combine lab-based techniques for recording jaw-muscle function with field research on primate feeding ecology, behavior and dental morphology. Moreover, the integrative nature of this project will identify additional links between adaptations and function in the primate feeding apparatus, feeding behavior and diet that may not be evident from any one independent research program.
Broader impacts of this study include the promotion of collaboration between scientists at four universities with different areas of expertise and the training of students through their active participation in research for this project. The integrative approach will provide these students with hands-on training in field techniques, electromyography, and mechanical properties and behavioral data collection and analysis. It is also expected that information on mantled howling monkey feeding behaviors will benefit conservation management decisions regarding the long-term sustainability of these primates and their habitats in Central and South America. Finally, this project is led by a minority female researcher, thereby contributing to minority representation in the sciences.
