Partner Series

Large breasts and hips on women. Broad shoulders, height and strong muscles on men. A woman's shinier head hair, and a man's robust facial hair: These are all examples of "sexually dimorphic" cues outward displays of masculinity and femininity, respectively, that help men and women attract mates. Another cue is the pitch of men's and women's voices.

Studies have found that the lower the pitch of a man's voice, the higher his testosterone level, which itself is an indicator of his genetic quality and sexual fitness. Time and time again, studies find that women tend to find men with lower-pitched or deeper voices more attractive. [What Is Pitch? ]

Women especially seek men with lower voices, as well as more masculine facial features, which are also tied to testosterone levels, when they're looking for short-term flings or uncommitted sex, and when they're ovulating. Evolutionary biologists speculate that in these circumstances, women may be seeking mates who are genetically fit (and will produce healthy offspring), rather than mates who they sense will be good caretakers in the long-term .

This could help explain why a 2009 study of the Hazda tribe in Tanzania found that men with lower-pitched voices tended to have more children.

Now, a new study published in the journal Memory & Cognition reports that women even remember information better when a lower-pitched male voice tells it to them than when a higher-pitched male voice does. No such difference exists in their memory of words spoken by low- and high-pitched female voices. [Why Do Men Have an Adam's Apple But Women Don't?]

"We were able to show that women's memory is in fact sensitive to masculinity cues in men's voice pitch," psychologist Kevin Allan of the University of Aberdeen and his colleagues wrote. First, this shows that memory is attuned to sexually dimorphic cues. Second, it supports the hypothesis that our memory intervenes to help us screen mates, in order to enhance our chances of producing healthy offspring.

Follow Natalie Wolchover on Twitter @nattyover. Follow Life's Little Mysteries on Twitter @llmysteries, then join us on Facebook.