Why We Kiss: Kissing Helps Find the Right Partner--And Keep Them

Why do we kiss? That's a good question, and one that researchers decided to look at a little more closely. Now, they've discovered that kissing helps us size up potential partners and, once in a relationship, may be a way of getting a partner to stick around.

"There are three main theories about the role that kissing plays in sexual relationships: that it somehow helps assess the genetic quality of potential mates; that it is used to increase arousal (to initiate sex for example); and that it is useful in keeping relationships together," said Rafael Wlodarski, one of the researchers in a news release. "We wanted to see which of these theories held up under closer scrutiny."

In order to learn a bit more about this behavior, the researchers set up an online questionnaire. Over 900 adults answered questions about the importance of kissing in both short-term and long-term relationships. This allowed the scientists to examine exactly what factors played a role in this particular behavior.

"Kissing in human sexual relationships is incredibly prevalent in various forms across just about every society and culture," said Wlodarski in a news release. "Kissing is seen in our closest primate relatives, chimps and bonobos, but is much less intense and less commonly used."

So what did they find? The survey responses showed that women rated kissing as generally more important in relationships. In addition, men and women who rated themselves as being attractive or who tended to have more short-term relationships and casual encounters also rated kissing as being more important.

This isn't necessarily surprising. In humans, as in all mammals, females must invest more time than men in having offspring. Previous studies have shown that women tend to be more selective when initially choosing a partner. In addition, men and women who are more attractive, or have more casual sex partners, have also been found to be more selective in choosing potential mates.

"In choosing partners, we have to deal with the 'Jane Austen problem': how long do you wait for Mr. Darcy to come along when you can't wait forever and there may be lots of women waiting just for him? At what point do you have to compromise for the curate?" said Robin Dunbar, one of the researchers, in a news release. "What Jane Austen realized is that people are extremely good at assessing where they are in the 'mating market' and pitch their demands accordingly. It depends what kind of poker hand you've been dealt. If you have a strong bidding hand, you can afford to be much more demanding and choosy when it comes to prospective mates."

The findings reveal a little bit more about the role that kissing plays in relationships. It turns out that, in fact, kissing can be used to help assess a partner and to actually keep a partner in a long-term relationship.

The findings are published in two studies in Archives of Sexual Behavior and Human Nature.