Sexual and aggressive behaviour in social groups of talapoin monkeys.

In social groups not all monkeys are equal, in terms of either their behaviour or their endocrine status. When a dominant monkey is compared with one that is subordinate the level of sexual behaviour is high in the dominant and low in the subordinate monkey, while levels of aggression received follow an inverse pattern. Attention in terms of visual monitoring is primarily focused on the dominant animal even when overt aggression is extremely low. Cortisol and prolactin concentrations tend to be higher in subordinate monkeys while only the dominant male shows elevated testosterone levels during group interactions with attractive females. A question of some importance is whether these differences in endocrine status are a determinant of the differences in behaviour or whether they reflect the behaviour and, if the latter, to what purpose. Recent attempts to answer this problem have focused on the hypothalmo-pituitary axis in order to examine whether differences in behaviour between dominant and subordinate monkeys are reflected in differences in its responsiveness to endocrine changes.