We find significant dose-response curves for social behaviors after single-dose administration of drugs in five adult male monkeys living in their "home" troop of about 30 animals. Ethanol (0 to 2 ml/kg, gavage) produced ataxia without motor slowing, regressive playful fighting typical of juveniles, and a substantial increase in the ratio of heterosexual to autosexual behaviors. Aggressive dominance behavior was not altered. Pentobarbital sodium (0 to 1 mg/kg, intramuscularly) reduced submission behaviors, increasing the dominance-to-submission ratio. Methamphetamine hydrochloride (0 to 0.5 mg/kg intramuscularly) decreased the dominance-to-submission ratio, while producing hyperactivity, stereotypies, and social unrelatedness. Morphine (0 to 0.4 mg/kg, intramuscularly) blocked sexual behavior without impairing motor activity.
The results may help to clarify some controversies arising from conflicting data in studies of drug effects on humans.