Although individuals are governed by simple rules, their interactions with each other and their environment leads to complex patterns. This book observes social systems ranging from simple single-celled organisms to very complex ones, such as humans. It examines groups of all sizes, from small as in certain species of primates, to very large as with some species of fish and social insects. Self-organization is widespread throughout the animal kingdom. This book illustrates the numerous aspects that demonstrate social organization, including group formation, task-division, foraging, dominance interactions, infant protection, language and voting.