Women with high-pitched voices apparently prefer deep-voiced, manly men, according to new research that sheds light on the rules of attraction.

Scientists research the features that make people attractive because these reveal what physical and mental qualities we favor, shedding light on what forces drive human evolution.

"People obviously prefer to marry and date people they consider attractive, but also are more likely to cooperate with attractive individuals, prefer to hire attractive people and even prefer to vote for those they think are attractive," said psychologist Benedict Jones at the University of Aberdeen in Scotland. "So, by understanding the factors that influence attractiveness judgments, we're really getting insights into something that's one of the most powerful driving forces behind social interactions."

Intriguingly, past research has shown that women with high-pitched voices are not only thought of as sounding more attractive but often have faces others consider more attractive as well. Further studies revealed these voices in women are often linked with higher estrogen levels, perhaps serving as a cue to their health and fertility.

Straight women who are attractive, in terms of whether they have hourglass figures and how beautiful others deem their faces, typically show particularly strong preferences for men with masculine faces - those with larger jaws and heavier brows, for instance. Such manly traits could be linked with a man's health, and thus women might be unknowingly vying for potentially healthier offspring.

In fact, past research has shown that deep-voiced men have more kids.

This suggested that maybe soprano-voiced women preferred macho, deep-voiced men as well, in essence, pairing up the most feminine with the most masculine.

"Over the years, many philosophers have suggested that it's impossible to understand beauty and attraction, largely because beauty lies in the eyes of the beholder," Jones said. "Our recent work shows that, although it's certainly true that people often differ in the types of people that they find most attractive, these idiosyncratic tastes can, to some extent, be understood and even predicted."

To test their idea, Jones and his colleagues first measured the pitch of the voices of 113 female college students. They next listened to recordings of men saying either "I really like you" or "I really don't like you," and were asked how attractive they found them. The voices of these men were electronically modified to have either higher-pitched, more feminine voices, or lower-pitched, more masculine voices.

The volunteers preferred the lower-pitched voices regardless of what the men were saying. In addition, the 20 women with the highest-pitched voices preferred masculine voices nearly 20 percent more on average than the 20 women with the lowest-pitched voices.

"The findings suggest that women's own attractiveness in some way influences their preferences for masculine traits in men's voices," Jones said. "Effects like those in our study might simply reflect people finding their place in the mating market and taking that into account when judging others' attractiveness."

"What's a little bit surprising is that we see these types of effects in studies like ours where people are judging the attractiveness of people they will never meet, never mind attempt to enter into a relationship with," Jones told LiveScience. "Awareness of our own market value seems to be so entrenched that we take it into account even in situations where we really don't necessarily need to."

An interesting direction for further research could be whether or not women with high-pitched voices actually enter into relationships with deep-voiced men.

"Is it an effect that's specific to attractiveness judgments, or does it also shape our decisions about who we enter into relationships with?" Jones wondered.

Also, instead of just using static pictures or altered voice recordings, "I'd be keen in the future to alter the appearance and vocal characteristics of videos of people in order to investigate how people combine visual and auditory cues when judging others' attractiveness," he added.

The scientists detailed their findings online April 23 in the journal Behavioral Ecology.