Female sexuality has evolved to be more fluid' for men to have multiple wives

The reason why women’s sexuality is more fluid than men’s could be a result of evolutionary design, a new theory suggests. Sexual fluidity might have arisen in women in order to reduce ‘conflict and tension among co-wives in polygynous marriages’, proposes evolutionary psychologist Dr. Satoshi Kanazawa. The benefit in this would be that being sexually fluid would have allowed women to have sex with their co-wives while still successfully reproducing with their husbands, the theory suggests.

Dr. Kanazawa explains that even though people of both genders are known to be sexually fluid, sexual fluidity is more commonly seen in women. Being ‘sexually fluid’ means a person may not adhere to a particular sexual identity, and can switch between homosexual, bisexual, and heterosexual identities. He says that, “Rather than being straight or gay, to whom women are sexually attracted may depend largely on the particular partner, their reproductive status, and other circumstances.”

He analysed the National Longitudinal Study of Adolescent Health to find out the differences between sexual fluidity in men and women. The study comprised measuring the sexual orientation of American youth in four ‘waves’, following them for a period of 10 years.

The analysis report showed that women were more fluid in all of proposed wave facets. Moreover, the study also confirmed his other hypotheses such as women who experience increased levels of sexual fluidity have a larger number of children, and that women who get married early or become a parent at a young age also experience high levels of sexual fluidity. The study has been published in Biological Reviews.