Over the years, researchers have tried to explain monogamy by studying attraction between the sexes. But in efforts to find out how people maintain relationships, some researchers look at more subtle clues - literally.
In a recent study, featured in the journal of Experimental Social Psychology, researchers at Florida State University looked at how relationship status influenced men's attraction to a woman throughout her menstrual cycle.
Single, male subjects rated a woman the most attractive at the peak of her ovulation, scientists found, which is to be expected since that's when she's the most fertile. On the other hand, male subjects in a committed relationship behaved the opposite by giving the woman lower attractive marks during her fertility peak.
Although it's been thought that women expertly conceal their ovulation cycles, some studies suggest that might not be the case. During ovulation, women's voices and appearance may seem more attractive to men.
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The FSU study spanned from three months and tested the perceptions of 38 college-aged men - 12 of which claimed to be in a relationship. The male subjects interacted with a 21-year-old female student who didn't know which men were in relationships. The participants routinely rated the female student's attractiveness at different stages during her menstrual cycle.