Role of oxytocin and vasopressin v1a receptor variation on personality, social behavior, social cognition, and the brain in nonhuman primates, with a specific emphasis on chimpanzees

Primates engage in a variety of complex social behaviors. Broadly speaking, these social behaviors can range from agonistic to affiliative depending on the context of a given interaction and a variety of other factors such as the sex, age, familiarity, and rank of individuals. Social interactions of any kind-whether cooperative or prosocial, as they is often termed, or conflict-and aggression-based, often termed antisocial-are based on the individual's personality and cognitive traits and are manifest in their communication and behaviors directed toward others. (Chapter 5 discusses the problems associated with this terminology.) In other words, similar to humans, within different primate groups there are individual differences in the frequency of behaviors that reflect the range of social behaviors that are expressed during social interactions. Understanding how or why this cluster of traits varies among individuals is therefore important for understanding social interactions. It is now clear that one source of individual variation in both competitive and cooperative behavior is genes. Two of the most widely studied are genes that regulate the receptor distribution of oxytocin (OXTR) and vasopressin (AVPRA, AVPR1B and AVPR2). (See Box 7.1 for an overview of terminology and concepts associated with genetic variation.)