Elsevier

Hormones and Behavior

Volume 30, Issue 4, December 1996, Pages 364-378
Hormones and Behavior

Regular Article
Nature Needs Nurture: The Interaction of Hormonal and Social Influences on the Development of Behavioral Sex Differences in Rhesus Monkeys

https://doi.org/10.1006/hbeh.1996.0042Get rights and content

Abstract

Thirty years of research on early social and hormonal environments and their relationship to the expression of behavioral sex differences in rhesus monkeys are reviewed. These studies demonstrate that whether aggressive and submissive behaviors are sexually dimorphic depends primarily on the social and not the hormonal environment. Early rearing environments without mothers or allowing brief periods of peer interaction produced higher levels of male aggression and female submission. Presenting behavior was expressed more by females than males in environments with high male aggressivity and female submissiveness. No sex differences in presenting occurred in low aggressivity environments, unless monkeys were reared isosexually, when males presented more than females. Rough and tumble play and foot-clasp mounting were consistently exhibited more by males than females across all rearing environments studied, but rearing environment affected the degree of the sex difference. When reared isosexually males displayed less, and females more, foot-clasp mounting than when heterosexually reared. No social environment increased the low frequency of female rough and tumble play. Suppressing neonatal androgen in males did not effect any sexually dimorphic behavior. Prenatal androgen administration to genetic females masculinized many aspects of their juvenile behavior, consistently increasing rough and tumble play and foot-clasp mounting across different social environments. Thus the sexually dimorphic behaviors which showed the smallest variability across social contexts were the most profoundly affected by the prenatal hormonal environment. These studies demonstrate that the expression of consistent juvenile behavioral sex differences results from hormonally induced predispositions to engage in specific patterns of juvenile behavior whose expression is shaped by the specific social environment experienced by the developing monkey.

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1In the text and Table 2, differences between males and females have been taken from the original author's analyses in each rearing condition. When an author stated that there was a sex difference in behavior this was regarded as accurate whether or not the author reported the statistical support for the conclusion. Cases where an explicit comparison was not made between males and females and the reported means were clearly comparable were regarded as the lack of a sex difference. In one case, presenting in Mother-Peer reared subjects reared in isosexual groups (Goldfootet al.,1984), the explicit comparison between males and females is not reported, but isosexual male presenting frequencies were severalfold higher than isosexual female frequencies during the 1st year of life. This is shown as a sex difference with a question mark to indicate that this sex difference is not verified.

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