Functional alterations in the social organization of bonnet macaques (Macaca radiata) induced by ovariectomy: an...

A group of seven ovariectomized female and three intact male Macaca radiata was compared to a matched control group of intact females and males during a breeding season. A second, replicate, experiment was conducted after the males had been switched between groups to partially control for seasonal effects and differences in the age of males. In the first experiment, 161 hr of quantitative data were collected and in the second, 93 hr. Differences in the social organization of the experimental and control groups were anticipated by five a priori evolutionary predictions focused on aspects of intersexual and intrasexual selection: (1) less affiliative and sexual behavior between males and ovariectomized females; (2) less intrasexual competition between them; (3) more intrasexual affiliation among males and ovariectomized females; (4) more intersexual competition between them and (5) more homogeneous patterns of use of resources. Sixty of 90 applications of these predictions to behavioral measures were confirmed. These admittedly exploratory a priori predictions thus significantly increased the ability to anticipate social consequences of female castration. Contrary to Predictions 2 and 4, ovariectomized females engaged in more intrasexual agonistic behavior and less frequently showed aggression toward males.