In a famous study, two social scientists raised a group of infant monkeys in complete isolation for the first few months of their lives. none had lived with a mother. later the scientists returned the monkeys to cages with other monkeys. when the monkeys reached adulthood, each was placed in a breeding cage with a monkey of the opposite sex. observers noted that the social, sexual, and emotional behavior of the isolated monkeys was distinctly abnormal. the females appeared fearful and viciously attacked the males when a sexual advance was made. the males, on the other hand, alternated between fear and overly enthusiastic, clumsy sexual advances. when a few of the females finally became pregnant and gave birth, they rejected the infants; some even killed their offspring