Traditional analyses of the evolution of intelligence have emphasized commonality and continuity among species. However, recent research suggests that humans might have specialized in a particular kind of intelligence that is related to understanding mental states such as desires, intentions and beliefs. Data indicate that the ability to reflect on one's own mental states, as well as those of others, might be the result of evolutionary changes in the prefrontal cortex. Behavioral studies in children and chimpanzees reveal both similarities and striking differences in the developmental pathways that lead to theory-of-mind capacities. Humans and great apes share many ancient patterns of social behavior, but it is too early to be certain if they interpret them in the same manner. Humans might have evolved a cognitive specialization in theory of mind, forever altering their view of the social universe.