“Kiss me and you will see how important I am,” Sylvia Plath wrote.

The erotic kiss (as opposed to the kiss of respect, friendship, courtesy, or parent-child) is recognized in most cultures around the world. The vast majority of adults all over the globe have experienced the awkwardness, excitement, confusion and pleasure of it. But one must admit that on its face the practice of kissing is more than a bit strange. Why would the exchange of saliva and dinner salad remnants be considered a desirable event, a ritual of passion? Given that the erotic kiss is so common, it must play an important role in the dance of human sexuality. But what exactly is that role?

Opinions among scholars differ as to the function and origins of kissing. One hypothesis is that the kiss has evolved as a mechanism for gathering information about potential sexual partners. A kiss brings us into close physical proximity with the other, close enough to smell and taste them. The face area is rich with glands secreting chemicals that carry genetic and immunological information. Our saliva carries hormonal messages. A person’s breath, as well as the taste of their lips and the feel of their teeth, signals things about their health and hygiene, and thus their procreative suitability.

Another hypothesis claims that the kiss functions primarily on the level of psychology, as a way to express and reinforce feelings of trust, closeness, and intimacy with another. Just like the clicking of wine glasses allows us to bring hearing into the sensory experience of drinking (which already involves all the other senses), so the kiss allows us to invite the senses of taste and smell to partake in the celebration of intimacy and make the event deeper and more complete. In addition, when we kiss someone, we bring that person into our vulnerable personal space and agree to take the risk of catching an infection or disease. A kiss is therefore an implicit expression of openness and trust. A kiss also shows that you do not recoil from the other’s bodily fluids. Recent research(link is external) has suggested that sexual arousal, especially among women, functions to suppress feelings of disgust. In this context, the kiss may serve as evidence and expression of sexual arousal. This theory predicts that kissing will not be an integral part of sexual activities where genuine desire and intimacy are absent. Indeed, the kiss is not common among sex workers and their clients, or rapists and their prey.

In addition, the research suggests a possible gender difference in how kissing is perceived and used. Men, in general, may regard less the kiss and the information it provides. Men tend to use kissing as a potential gateway to intercourse. They are more willing to forego kissing for intercourse, and their interest in kissing their spouses decreases over time. Women, in general, may regard the kiss as more important and attribute to it more meaning in the process of choosing a partner and maintaining a relationship. Women tend to see kissing less as a sexual act and more as an intimate act. Women rely more on the kiss to identify and assess a potential partner. They tend to be more attuned to the taste and smell of the man, and are much less willing to have sex without kissing beforehand. They are also somewhat more likely to use a bad kiss as reason to break off contact with a potential lover.

Despite the differences in attitudes towards it, kissing, it seems, benefits both genders. Generally, couples that kiss more frequently report improved and more satisfying relationships.

This article was taken off of Psychology Today. We do not claim to own it.