The primary objective of this proposal is to study the dietary choices demonstrated by an ape (the chimpanzee) and several congeneric species of monkeys in the Kibale Forest of Uganda. Physical anthropologists have for many years debated the reasons for the grater success of monkeys relative to apes since the Miocene and the clear diminution in the number of species of ape. Wrangham has hypothesized that the success of the monkeys has been due to their ability to process secondary compounds in vegetation more effectively than apes. These compounds are a variety of toxins which limit the food choices of animals unable to detoxify and digest them. Confirmation of this hypothesis will be advanced by observation of the food choices of the two primates during a synchronous study. In this study the investigators will observe the food choices of the study species during feeding in order to quantify the dietary intake. In addition samples of the foods will be gathered for laboratory analysis. The data will then be analyzed for food choices and composition and the used to clarify the habitat utilization by this ape and the three monkey species.