Differences in blood levels of androgens in female talapoin monkeys related to their social status.

Abstract

Serum testosterone and androstenedione levels were lower in the subordinate female talapoin monkeys of four social groups than either dominant or intermediate-ranking females. This was found in both intact or ovariectomized (oestrogen-treated) animals, which suggests that androgen from the adrenals contributed to this rank-related endocrine effect. These differences disappeared when the females were housed singly, levels in all animals becoming similar to those in subordinates in the group cage. There were no rank-related differences in progesterone levels during either the follicular or luteal phase of the cycle in intact females, or in those of ovariectomized females of different rank, but cortisol was highest in dominant group-living animals in these experiments. Significant correlations were found between androgen levels in group-living females and the amount of sexual interest shown in them by males; the amount of aggressive interaction involving each female did not correlate with her androgen levels. Social rank is defined according to the direction, not the amount, of aggression. These findings suggest that the social hierarchy regulates androgen levels in these female monkeys; there may also be effects on the ability of females to respond to their own, or to administered, androgen. Similar findings have been made previously in male talapoins. Since androgens fill a critical role in the sexual behaviour of both sexes in primates, this may be a neuroendocrine mechanism of general significance relating behaviour to social rank.