The evolution of human cooperation

We argue that cooperation is instinctual. Human cooperation conferred advantages to individuals in the ancestral environment in which evolution occurred. Explanations of the evolution of cooperation for any species (human, pre-human, and non-human) have to be consistent with the biological, physiological, and environmental constraints that existed in the ancestral environment during which evolutionary selection occurred. Our explanation is consistent with: (1) the anatomical evolution of humanity; (2) the paleontological and chronological evidence; and (3) modern biology.