Primates as models of behavior in biomedical research

Much can be learned about behaviors with biomedical relevance from behavioral studies of the seemingly uncomplicated prosimians to the seemingly complex great apes. This chapter will concentrate on providing insight into suitable, and perhaps even ideal, nonhuman primate (NHP) models that can be used, or that have been used, to attempt to answer specific behaviorally oriented biomedical research questions. Prosimians, monkeys, and apes are all organisms whose behavior has been investigated in the laboratory in an attempt to model, to simulate, to understand, or to change behavior. One of the primary biomedical uses of behavioral research with NHP is to identify, study, and treat behavioral abnormalities. A second important biomedical use of behavior is as an assay. Normal behavior can be assessed during a baseline condition and then an experimental manipulation can be implemented, with any significant changes in behavior being indicative of a meaningful effect of the manipulation. Nonhuman primate subjects can also be trained to perform specific tasks until they have reached target criteria and the effects of manipulations on performance can then be measured. For investigations focusing on the evolution of behavior, primate behavioral capabilities can be studied to better understand the evolution and/or development of human capabilities. Rhesus and cynomolgus macaques are the two most commonly utilized nonhuman primate models in studies of behavior. These medium-sized animals appear to represent a valuable compromise model, retaining many of the most attractive and useful characteristics of NHP as behavioral models, while simultaneously demonstrating many of the convenient and utilitarian characteristics required for successful laboratory animal models. Although specialized studies will require more specialized nonhuman primate models, rhesus and cynomolgus macaques appear to be exceptionally useful models for a variety of types of behavioral research.