Why do people live in groups? How does group living affect the way animals communicate? In this course, we will explore the evolutionary origins of cooperation and group communication in humans. The ways that people interact socially, including how we choose our friends and what we talk about, can be understood through the lens of evolutionary theory. We will examine the nature of conversation and discover not only how conversational behavior shares many features with other coordinated activities like music and dancing, but also how interpersonal communication strategies reveal important features of our fundamentally social nature.