Chimpanzees reared during early life in environments with social and perceptual restrictions are strikingly different from animals reared by their mothers in a natural habitat. As adolescents they avoid social contact and display little species-typical behavior; they play and copulate infrequently and do not groom. The authors found these aberrations to be very resistant to modification by a variety of maneuvers, including contact with normal social partners, drugs, and experimental manipulations, and they discuss the implications of their lack of "therapeutic" success.Abstract Teaser