Abstract
Social behavior is a fundamental part of life. Humans are a social species: from the moment of our birth, we succeed based on our ability to interpret and affect the behavior of those around us. All animals, and even unicellular organisms, recognize and interact with other members of their own species.
Similar patterns of social behaviors are seen in very different animals. For example, aggressive behaviors are recognizably similar in fruit flies, lobsters, and mammals, and they are regulated by some of the same kinds of genes. These common properties suggest that aggressive behaviors did not arise many times independently in different species – instead, it is likely that aggressive behaviors and other social behaviors go far back in evolution, and that ancient biological systems are involved in these behavioral processes.
What are the most fundamental social behaviors, and how are they organized at a biological level? Social behaviors in many animals, and in humans, are regulated by chemicals called neuropeptides that are some of the oldest signaling molecules in the nervous system. The best known of these molecules are called oxytocin and vasopressin. Oxytocin and vasopressin have widespread roles in animals in affiliation between mothers and their offspring, and between males and females in mating. Understanding how these molecules modify information processing in the brain helps us understand the basic structure underlying social behaviors.
How do genes and the environment interact to generate behavior? The central mystery of social behavior is that on the one hand it is innate, which suggests a biological basis, and on the other hand it is highly sensitive to the environment, learning, and context. Understanding how the brain interprets the world requires us to integrate our understanding of genes, brain circuits, and ongoing experiences that modify behavior.