Female intrasexual competition and the detection of cyclical fertility status

Previous research has shown women become more competitive towards other women when they

are most likely to conceive. However, the question of whether women can detect the fertility

status their rivals and the consequences of being able to do so, has largely been ignored. Our

results are the first to show that cyclical infertility is preferred by women judging the facial

appearance of other women who were presented as “rivals”. Luteal phase images were

significantly favored compared to those taken during either the follicular or menstrual phase,

under scenarios where the presence of a fertile rival could threaten mate procurement or female

social bonds. They support a hypothesis that an ability to detect fertility, and to be wary of it,

may be part of an evolved strategy that modulates female/female agonistic interactions whereby

women prevent their allies and potential sexual partners from having contact with ovulating

women.