"...says women have evolved to cheat on their mates during the most fertile part of their cycle, but only when those mates are less sexually attractive than other men.
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"We're claiming the desire to cheat is what evolved in women, that they may notice they have these desires at a certain point in their cycle," said Elizabeth Pillsworth, co-author of the study and an assistant professor of communication and psychology at UCLA. "Whether they translate into unfaithful behaviors is a matter of their own choosing. Cheating is a choice."
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"The exception was women who have very sexually attractive partners," Pillsworth said. "These women did not flirt with other men when they were at high fertility."