ABSTRACT
Introduction to Part Two The capacities of nonhuman animals to experience pain, to have a sense of consciousness embedded with cognitive abilities, and to have emotional lives is a challenging and controversial set of topics. On the one hand, a seemingly boundless set of examples of complex behaviors of these animals that correspond to sophisticated human behaviors are regularly reported by people with interest in and experience with individual animals, including pet owners, zoo personnel, farmers, and ranchers. On the other hand, scientists often have struggled to understand these topics in light of contemporary understandings of neurology, anatomy, biochemistry, physiology, ethology, and behavioral ecology of representatives of these various animal groups. Slowly some coherent pictures are emerging.
