Only recently have researchers begun to appreciate the importance of studying the neurobiology of social cognition (Ochsner & Lieberman, 2001). This growing interest stems from evidence suggesting that dysfunction of structures within the neural network subserving social cognition may be at the origin of many neuropsychiatric disorders in humans. Reports of clinical cases with circumscribed lesions, as well as the results of neurostimulation, neurorecording, and neuroimaging of normal and impaired brain, have all provided evidence that there exists specific neural circuitry involved in the processing of social skills (for review see Adolphs, 2001). In addition, animal studies examining the neurobiology of social cognition have refined our knowledge of the brain systems that underlie such abilities and are helping us better understand how human social and emotional processes are realized (Raleigh, 1995). In this respect, nonhuman primates are undoubtedly excellent animal models, not only to investigate brain processes underlying social cognition and to determine the long-term behavioral outcomes of early dysfunction in the neural structures mediating social cognition, but also to determine the modulatory impact of perinatal experiences on brain and behavioral development (Sánchez, Ladd, & Plotsky, 2001).

Investigations of the social skills of nonhuman primates in the wild or in the laboratory have revealed that monkeys, like humans, live in social groups that are characterized by complex and dynamic social organizations maintained through a variety of specific, long-term relationships between individual group members (Cheney & Seyfarth, 1990; DeWaal, 1989).