Creatures intermediate between ape and man, who walked erect, used tools, and hunted in groups, have existed for some 2 million years. Members of the genus Homo large-brained creatures who made more extensive use of tools, hunted large animals, and, sometime late in their evolution, acquired the use of fire—appeared at least 600,000 years ago. Man in his modern form, Homo sapiens, with a brain the size of ours, relatively well-perfected hunting techniques, cave art, burial and presumably other religious rituals, has existed for 60,000 years. This chapter follows the course of the social instincts from ape to man, drawing on recent observations of hunting and gathering cultures. The unique features of man's evolution were noted, particularly the change in brain size on which language and culture depend. Human instincts were reviewed and certain central conflicts—dependency and independence, pleasure and renunciation, and aggression and its control—described. The chapter traces major themes in the development of human personality.