Social Influences on Sex Differences in the Behaviour and Endocrine State of Talapoin Monkeys

Abstract

Publisher Summary The social environment is known to influence sexual behavior in several mammalian species, either by a direct action on the expression of behavior or indirectly by modifying endocrine states. This chapter describes how a monkey's neuro-endocrine system responds to the factors that shape and organize its society and determine its individual role in that society. The social environment has an important influence on the expression and suppression of reproduction in both males and females, and many behaviors other than sexual are also influenced according to the social hierarchy, particularly the aggression. Although aggressive behavior among females is less frequent than among males, social status also has consequences for endocrine state as well as for many behaviors. The endocrine profiles that are observed in subordinate individuals, particularly the high prolactin and low luteinizing hormone (LH) suggest differences in the activity of the brain's endorphin system. Low ranking males did not show any enhancement of sexual behavior on treatment with naltrexone. Opiate blockade does not alter aggression, but a consistent effect of the drug is a marked increase in grooming invitations and hence grooming received, irrespective of rank, in both males and in females. However, until a direct measure of changes in or a means of manipulating specific parts of the opiate systems is available, the current interpretations of the data remain in the realms of speculation.