When a Kiss Is Not Just a Kiss

One reason women cited for having sex turned out to be quite simple: The person was a good kisser. Why kissing might impel a woman to have sex, though, turns out to be complex. Viewed from a primatological perspective, it’s a strange activity. Other than bonobos, humans appear to be the only primate that engages in osculation, as kissing is technically called. Kissing between romantic or sexual partners occurs in over 90 percent of cultures. People kiss with great relish and variety—gently, shyly, affectionately, exuberantly, lasciviously, hungrily. Human lips are densely packed with sensory neurons, more than most regions of the body, but the tongue, nose, and cheeks also come into play. Typically kissing involves information transfer between most of the senses—touch, olfaction, and taste being the most prominent, although sights (luscious lips) and sounds (the English language has no words for this) cannot be ignored.

One study found that kissing caused a drop in cortisol, a stress hormone, indicating a reduction in anxiety. Kissing conveys information about health status, since bad breath can be a sign of disease or ill-health. Women also seem to use kissing as an emotional litmus test, with the outcome revealing whether they should take things to the next level and sexually consummate a relationship. Kissing seems more important for women than for men for this function. Whereas 53 percent of men in one study said that they would have sex without kissing, only 15 percent of women said they would consider sex with someone without first kissing them. Kissing not only provides vital information about a partner, it also can increase sexual excitement, feelings of euphoria, and a sense of emotional closeness.

“Bad” kissing is definitely a sexual turnoff for most women. One study found that 66 percent of women (as compared with 58 percent of men) admitted that sexual attraction evaporated after a bad kiss. As Alex “Hitch” Hitchens, played by actor Will Smith, told his client in the popular 2005 movie Hitch, “One dance, one look, one kiss, that’s all we get . . . one shot, to make the difference between ‘happily ever after’ and ‘Oh? He’s just some guy I went to some thing with once.’ ” In short, kissing provides information to a woman about whether she wants to take things to the next sexual level, reveals something about whether someone will be a good lover, may provide information about health and genetic compatibility, and provides a barometer of relationship quality.