Living Reference Work Entry

Encyclopedia of Evolutionary Psychological Science

pp 1-5

Date: Latest Version

Alloparenting and Female Same-Sex Behavior


Bisexuality; Helpers at the nest; Same-sex behavior


The alloparenting hypothesis posits that female sexual fluidity – “situation-dependent flexibility in women’s sexual responsiveness…that makes it possible for some women to experience desires for either men or women under certain circumstances, regardless of their overall sexual orientation” (Diamond 2008, p. 3) – was selected because it facilitated the acquisition of and bonding to an alloparent (a non-biological caregiver for one’s offspring).


As Darwin outlined in The Descent of Man (1871), reproduction is the engine of evolution. Sexual selection favors traits that increase an organism’s ability to reproduce; therefore, seemingly counterproductive behaviors such as same-sex sexual activity and romantic relationships pose an evolutionary puzzle. Although there have been several hypotheses put forward to attempt to explain same-sex sexual behavior in men [cite relevant Encyclopedia entries here], relative ...

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