The International Journal of Comparative Psychology is sponsored by the International Society for Comparative Psychology, an affiliate of the International Union of Psychological Sciences. In consonance with the goals and activities of the Society, it publishes studies on the evolution and development of behavior, broadly defined, and in all animal species; on the use of the comparative method for the understanding of behavioral processes; and the examination of the adequacy of psychological and evolutionary theories. It accepts for review articles that deal with historical and contemporary relationships between humans and other animals, that elucidate problems of homology of processes between human and non-human species, that explore the relationship between animals and changing environments, that provides an historical perspective on human evolution, that explicate fundamental concepts about human evolution, and that present research results and develop theories about the development and evolution of behavior. All papers published in the journal are open source and available free of charge, without the requirement of a journal subscription. This is invaluable for faculty and students at institutions with limited library resources in the United States and the would, to insure the widest possible dissemination of work of our authors.