I am broadly interested in the dietary ecology of Primates, including human ancestors and modern humans. I have worked extensively on the dietary ecology of a number of indigenous groups in the Brazilian Amazon to document their uses of forest products, both plant and animal, not only as foods but also as medicines. I have also carried out fieldwork with a number of non-human primate species including howler monkeys, spider monkeys and woolly spider monkeys. My present research is focused on the study of interactions between wild howler monkeys and their host-specific insect parasite, the howler monkey bot fly. At present, we are in the process of establishing a genetic data base for howler monkeys and bot flies that will allow us to examine novel aspects of the interactive biology of these two populations. I continue to be involved in my long-term project (36 years thus far) on the population dynamics of wild howler monkeys in Panama. Conservation biology, nutrient and anti-nutrient components of wild plant parts, and digestive physiology are also research interests.