Women judge the attractiveness other women more harshly when at their most fertile, suggests a new study. The phenomenon could be a strategy to devalue potential rivals, says the psychologist behind the work – being bitchy about others could help a woman win the attention of a desirable man.


Theories of sexual selection in most species usually concentrate on how males compete for females. But recent theories for humans suggest there is intrasexual competition among females as well, as males can vary markedly in their abilities as providers and protectors.



Maryanne Fisher, a psychologist at York University in Toronto, Canada, decided to try to find evidence for female competition by presenting heterosexual students with photos of faces. She found that when women were in the most fertile phase of their menstrual cycles, they rated the attractiveness of other women lower than when they were not.



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