An interesting article came up today on phys.org, summarizing a recent scientific paper in Biological Review (sadly pay-walled.) The paper proposes an evolutionary model that suggests that women may be sexually fluid - changing their sexual desires and identities from lesbian, to bisexual, to heterosexual, and back - to reduce conflict/tension in polygynous scenarios while maximizing reproductive success. It also proposes this may account for male arousal by lesbian sex.
While the article is sparse and the scientific paper is pay-walled there are some interesting tidbits to be found in the abstract, including "Analyses of the National Longitudinal Study of Adolescent Health (Add Health) confirm the theory's predictions that: (i) women (but not men) who experience increased levels of sexual fluidity have a larger number of children (suggesting that female sexual fluidity, if heritable, may be evolutionarily selected)". On the other hand, the author has some interesting articles in their history.
So what do you guys think?