The Great Apes (chimpanzees, bonobos, gorillas and orangutans) are our closest living relatives, sharing a common ancestor only five million years ago. We also share key features such as high intelligence, omnivorous diets, prolonged child-rearing and rich social lives. The Great Apes show a surprising diversity of adaptations, particularly in social life, ranging from the solitary life of orangutans, through patriarchy in gorillas to complex but different social organizations in bonobos and chimpanzees. As Great Apes are so close to humans, comparisons yield essential knowledge for modeling...