When a woman is ovulating, her behavior changes in a startling number of ways from the way she walks, talks and dresses to the men she flirts with, according to new research.
The findings might offer some practical tips for women to boost their online dating prospects; for scientists to develop new kinds of ovulation detection kits; or for marketers to target sales of clothes and jewelry. The work also suggests that going on or off the birth control pill might influence a woman's choice in men.
Why does ovulation change women's behavior in such subtle yet fundamental ways? Experts propose that it's an innate and subtle strategy to both attract the most desirable guys and convince them to stick around for the long haul.
"The idea is that women turn up everything that has to do with femininity" at ovulation, said Greg Bryant, an evolutionary psychologist at the University of California, Los Angeles. "This is showing that there are all sorts of phenomena that happen in our behavior that we're not actually aware of."
For a long time, scientists assumed that the hormonal shifts of ovulation happened without measurable changes in how women behaved. That's because women have a strong motivation to hide the fact that they're fertile, unlike other members of the animal kingdom. While a female baboon's swollen red rump encourages males to mate and go, for example, a female human's ability to keep a man guessing should up the chances of him mating and then staying to help take care of their children.
A desire for masculine men
Starting in the 1990s, studies began to show that in the days before ovulation women start to become more attracted to men who have deeper voices and more chiseled, masculine and symmetrical faces. According to some studies, that may be because men who look like George Clooney are more likely to have dominant social roles, better genes and stronger immune systems.
Women who are in relationships exhibit the most extreme spike in interest for masculine men around ovulation. The shift is even more exaggerated when they're not happy with their current partners, said Kristina Durante, a social psychologist at the University of Minnesota, Twin Cities. Women are also more likely to cheat on their partners while ovulating.
Fertile women may even be better at getting the men they want. Adding to findings that men prefer the smell of women who are more fertile, a study published last year in the journal Psychological Science found that testosterone levels were higher in men after they smelled T-shirts worn by ovulating women than after smelling T-shirts worn by women who weren't ovulating. Higher testosterone levels imply a higher likelihood of striking out in romantic pursuit.
More attractive during ovulation
Another study, published in 2007 in the journal Evolution and Human Behavior, found that lap dancers raked in higher tips when they were most fertile.
In addition to changes in looks and smells, Bryant and colleagues have measured a subtle but detectable shift upwards in the pitch of a woman's voice when she's approaching ovulation. Her voice reaches its highest pitch on the day before and the day of the egg's release. Now, he's trying to figure out if a higher pitched voice is indeed more attractive to men.
In other work, scientists have found that ovulating women sway their hips more while walking, though they hold their upper bodies in a more defensive position. Fertile women also show more skin, and they are more interested in going to social gatherings.
In one of the latest studies, reported by Durante and colleagues in an upcoming issue of the Journal of Consumer Research, women chose slightly sexier and more revealing clothes, shoes and accessories when they were at their most fertile. The researchers also found that women made their fashion choices not necessarily to attract men directly but to out-compete other women.
Knowing how ovulation affects them could help women make smarter choices about dating, shopping and more.
"If women are aware of the five or six days in their cycle when they're most fertile, they may be more likely to become more or less attracted to different types of men, or they might want to rein in their purchases if they happen upon a Victoria's Secret," Durante said. "Your picture might look more attractive near ovulation, so take your Facebook picture mid-cycle."
Starting or stopping any method of hormonal birth control might also affect your feelings about your partner — or someone else's.
"The thought might be upsetting to many women, but that's what researchers are thinking," Durante said. "When you are ready to pick a mate, go off the pill."