Health & Wellness

Pucker up! People use kissing to size up potential mates

If a new study from a team of Oxford researchers holds up, men hoping to attract the woman of their dreams had better work on their kissing.

In the survey-based study, published today in the Archives of Sexual Behavior, women declared kissing to be much more important than men did — so important they’re more likely to change their opinion of a man’s desirability based solely on a kiss.

Using an online survey technique polling 308 men and 594 women between the ages of 18 and 63, Rafael Wlodarski and Robin Dunbar of the department of experimental psychology at the University of Oxford, found that people used kissing as a way to judge a potential mate, and to help establish and maintain a bond, but not to become sexually aroused.   

Why people kiss has long interested scientists.

In primates, it’s a social bonding tool, according to Frans de Waal, the C.H. Candler professor of primate behavior at Emory University, and one of the world’s leading experts in primate society.

Kissing among apes is common, most often used as a greeting or a means of conflict resolution, de Waal said. In chimps, the kiss often resembles a toothy gnaw on a shoulder, though sometimes on the mouth, too.

“Bonobos are even closer to what you would call human kissing,” he said. “More open mouth put on another’s mouth, sometimes including tongue action. But it’s more a playful thing, not so much a sexual thing.”

After kissing, primates who’ve been arguing calm down and re-establish friendly relations. When a member of a primate troop has been gone, and returns, other members often kiss it.

Kissing evolved, goes the prevailing theory, by the transfer of food from the mouth of a mother to the mouth of babies.

A perfect kiss may help partners choose potential mates, whether they're royals like Prince William and Duchess Kate, or mere mortals.

What's in a kiss?
But why do people do it? To find out, the Oxford researchers asked people to rate their own sexual attractiveness, their socio-sexual styles — short term and one-nights stands versus looking for a long-term partner — and gender. Then they were asked to indicate in which situations they kissed and how important kissing was. 

When they sifted through all the answers, the researchers concluded that kissing wasn’t really used as a way to create sexual arousal, but was used to judge the value of a potential sexual partner and, as in primates, to help establish or maintain a social bond.

Women were especially attuned to kissing quality. In answer to the question “Have you ever felt attracted to someone, only to find that your attraction to them had changed after an initial kiss?” the results showed that “women were more likely than men to have experienced a change in attraction after an initial kiss.” 

The more attractive the woman, the more likely she was to have changed her mind if a kiss wasn’t up to snuff.

Furthermore, women valued “having a partner who was a ‘good’ kisser,” more than men. More kissing, and more satisfaction with that kissing, as well as more sex in the relationship, “were all positively associated with relationship quality.”

Sizing up a potential mate
A growing number of studies are showing that when two potential mates are close to each other, they unconsciously exchange a great deal of information about genetic fitness, health and fertility.

Immune system “compatibility information is passed in human pheromonal cues,” Wlodarski said, possibly in saliva, but more likely by scent. “Kissing in many cultures can take the form of sniffing or inhaling the other. I would guess that this is the more likely mechanism which allows individuals to assess potential mates.” 

Studies have shown that women can detect some immune system information from men through smell. And men can detect when women are ovulating. Neither gender is aware, but, for example, female strippers earn higher tips when they are ovulating. Close contact through kissing could help that exchange.

Massage, eye gaze, touching have all been shown to engage oxytocin and reward brain circuits relieving anxiety and increasing trust.

“Kissing in established relationships probably works to strengthen bond between individuals via these types of mechanisms,” Wlodarski said, “by establishing trust, intimacy, and the release of various neurotransmitters and neuropeptides,” like oxytocin and dopamine.

That’s probably why even long-married couples who often touch and kiss, even if they’re not having much sex, report good relationship satisfaction.

That may also be why the people in Wlodarski’s survey reported much more kissing before sex rather than during sex or even after sex. It was not to get aroused, but to feel relaxed and intimate. 

Brian Alexander is a frequent contributor to NBC News and a co-author of “The Chemistry Between Us: Love, Sex, and the Science of Attraction.”