- If you think someone is promiscuous, you might well be right. In a recent study conducted in the UK and published in Evolution and Human Behavior, Lynda Boothroyd showed that both men and women were able to judge the openness of men and women to a sexual fling based on photographs of their faces. The study showed that both genders judged men who looked "masculine" and women that looked "attractive" as, correctly, more open to casual sex.
- Who a woman wants to sleep with — and her openness to doing so — varies with her cycle and her age. A variety of studies have shown that women get hornier right before they ovulate, and a study by David Schmitt of Bradley University shows that women's preferences in men vary around the same time. In addition, another study conducted in 48 countries shows that women's openness and propensity to engage in intercourse with multiple sexual partners (including infidelity) peaks in her 30s, while, for men, it peaks in their 20s. Schmitt hypothesizes that this is because women's fertility begins to decline at that point in her life.
- It does have to do with your mommy (or daddy) issues. Jay Belsky, in study published in Child Development, found that women who grew up in stressful family situations tended to have more kids early without waiting for stable relationships because, he hypothesized, they were sure one was coming. He wrote, "harsh parenting in the first four years of life predicts early puberty and growth and thereby predicts more unrestricted sexual behaviour by the time the child reaches 15 years of age."
- It's still about trust and security. A variety of studies of both men's and women's propensity to sleep around is based in their ability to trust or feel secure in relationships. Schmitt says, "If a person was high in being able to trust other people, they were monogamous. If they were very low in trust they were much more likely to be unrestricted in sociosexuality." He relates this, like Belsky, to childhood stresses and poor relationship models.
- Sleeping around might be related to testosterone in both sexes. A study Sarah Mikach and Michael Bailey of Northwestern University looked at the correlation between a woman's sexual partners and how they look, felt or acted more stereotypically masculine and found, somewhat unsurprisingly, that woman who were identified as more "masculine" tended to have more sexual partners. Of course, it all depends on the definition of "masculine behaviors," but even when just taking biology into account, the theory seems to hold. Researchers believe that having a longer ring finger than index finger is related to prenatal testosterone exposures — and a study by Andrew Clark in Evolution and Human Behavior found that women with longer ring fingers tended to have more sexual partners as well.
- Oh, and, yes, there is a social aspect to all of this. Biology is all well and good, but thousands of years of judging male and female sexuality differently does have more than a little something to do with women's ability to act on their legitimate sexual desires. Schmitt points out that, with the expansion of birth control, education, and access to social services for women, their ability and willingness to act on sexual urges definitely increases. Fhionna Moore at the University of St Andrews found in her work that financially independent women didn't tend to seek out so-called "good providers," as much as they did supposedly good
jeansgenes. Basically, once a society begins to near equality for men and women, providing women with more autonomy and less of an incentive or requirement to buy into patriarchal sexual mores, they don't — and then many of them go have a bunch of sex.
Socially-influenced common knowledge — often disguised as evolutionary theory — holds that men are biologically inclined to have sex with as many women as possible to spread their seed, while women are biologically inclined to sink their claws into one man, push out kids for him to support and never, ever cheat. This theory on How The World Works ignores the rather convenient fact that, biologically, women have the same incentives to diversify the genetic contributions to their offspring as men do and — it must be said — like sex just as much if not more. So why is it that promiscuous women are supposedly such an anomaly? And are they? Mairi Macleod tries to answer those and man other questions in an epic article on sexuality in the latest New Scientist. After the jump, a rundown of her article's conclusions.