Behavioral and physiological suppression of fertility in subordinate marmoset monkeys.

In laboratory groups of common marmosets (Callithrix jacchus jacchus), socially induced reproductive suppression among subordinates and offspring effectively maintained a monogamous breeding system. Male subordinates or male offspring were inhibited or restrained from showing sexual behavior, while similarly placed females could also suffer from complete ovarian failure. In well-established families, a familiarity or inbreeding taboo restricted reproduction among otherwise fertile offspring. However, only one daughter ovulated in any family, and in up to 50% of family groups, all daughters were inhibited from ovulating. This differential effect on daughters may have reflected a qualitative shift in the mother-daughter relationship: the ovulating daughter may have represented the next breeding female and may no longer have regarded the mother as an inhibitory influence. In newly established peer groups of pubertal and postpubertal offspring, one male and female dominated all others in each group and overtly inhibited sexual behavior in subordinates of their own sex. Ovulation was suppressed in all subordinate females because of inadequate gonadotrophin secretion. This was not related to increased secretion of cortisol or prolactin, but may have been related to hypothalamic inhibition of luteinizing hormone-releasing hormone (LHRH) secretion.