Social and hormonal influences on behavior of adult male, female, and pseudohermaphroditic rhesus monkeys

Abstract

We previously demonstrated that in a simple pair test situation the expression of adult male sexual behavior by rhesus monkeys depends on both prenatal (organizational) and adult (activational) androgen exposure. In the present study we used a more complex social situation (trio tests) to evaluate the behavior of males, females, and female pseudohermaphrodites. In these trio tests, the experimental subjects were tested with two estrogenized stimulus females simultaneously. Sex differences in behavior were made apparent by this complex testing situation that could not have emerged in the pair test. Gonadectomized males and female pseudohermaphrodites, but not ovariectomized females that were concurrently receiving TP, exhibited increased male sexual behavior in trio tests compared to pair tests. In trio tests, the males and pseudohermaphrodites showed evidence of partner preference by interacting almost exclusively with one of the two stimulus females. These “preferred females” in turn were responsible for the majority of the proceptive behavior exhibited in these tests. Ovariectomized females rarely displayed male sexual behavior in either test situation. These results further support the hypothesis that prenatal androgen exposure predisposes monkeys to exhibit masculine behavior traits when they reach adulthood and are exposed to the activational influences of androgens.