The human species is the product of a long evolution. Humans share the general primate heritage as intensely social, aggressive, sensual, curious, and intelligent creatures. In addition, one can possesses own uniquely evolved linguistic and cultural characteristics. This chapter views primates from the evolutionary perspective and develops a theory of instinctual-emotional systems. As complex species—the outcome of long and many-faceted selection process—primates possess instinctual systems which set the limits or form the boundaries of their perceptions and actions. Primates are social animals; from birth to death their lives are intimately bound up with the other members of their group. Primates are active explorers, "opportunists" who are prepared to take advantage of their surroundings. Exploration and nonsocial play are useful in the discovery of food, the development of motor skills, and familiarization with the environment. The discussion of primate social instincts draws on ethological work, laboratory studies of monkeys and, most heavily, field observations of monkeys and apes.