The Anatomy of a Kiss

· February 12, 2018

Although kissing is an everyday thing, it is still a bit of a puzzle. We don’t know for sure what purpose it serves. Nor do we agree on whether it is learned behavior, or instinctual.

Science has been trying to get to the bottom of it. The goal is to determine the anatomy of a kiss, and what effects it has.

Charles Darwin, the father of the theory of evolution, wrote about the nature of the kiss.  In his work The Expression of the Emotions in Man and Animals, Darwin noted that the gesture was, more than anything, one of sociability. 

He said that a kiss is a result of an innate desire to be recognized and to establish relationships. It is a way to “receive pleasure from close contact with a loved one.”

Nevertheless, there is data that calls into question these statements. For example, we know that 10% of the cultures in the world do not include kissing as part of their customs. 

There are also societies that gave a different meaning to kisses. So, it seems we cannot universally reduce the anatomy of a kiss to an expression of love.

“The good thing about the years is that they heal scars. The bad thing about kisses is that they cause addiction.”

-Joaquin Sabina-

The anatomy of a kiss from a biological standpoint

From a physical point of view, a kiss is “the mouth to mouth contact between two people or the pressure of the lips of one person on the body of another.” 


This is the definition written by Sheril Kirshenbaum, a research biologist from the University of Texas. This is the most basic anatomy of a kiss.

Interestingly, when you kiss someone, 32 different anatomical elements come into play.

gif of a kiss

From a physiological standpoint, a kiss is much more complex. The gesture is like an exchange of sensory information. It involves the senses of taste, smell, and touch. A kiss also includes a chemical reaction, whose messengers are pheromones.

When you kiss someone, you trigger a flurry of hormonal activity in your body. Oxytocin starts to flow into your bloodstream. As you know, this hormone is known as “the love hormone” and makes you feel good.

Along with all of this, at the end of the kiss, the body unloads a big dose of serotonin. This also promotes a feeling of well-being. For all of these reasons, it makes sense to say that the anatomy of a kiss is also the anatomy of a pleasurable moment.

The meanings of a kiss

One of the questions we posed at the beginning is whether kissing is instinctual or learned behavior. There are several facts that tilt the balance towards the second explanation. One of those is the use of the kiss throughout history.

For example, in the Middle Ages, the kiss was prohibited for a period of time. Back then, only illiterate servants used the kiss. And it wasn’t because they liked each other. They used it to seal contracts because they were unable to sign them.

Likewise, researchers have established that the anatomy of a kiss means different things for women and men. Women value it more. They see it as an end in and of itself. They appreciate the gesture before and after sex. Men, on the other hand, think of it as a direct precursor to sex.

ancient art

Other interesting facts about a kiss

Although it seems that humans are ruled by culture over instinct, this last factor also is of great importance in the act of kissing. We can prove this with a simple fact.

Our ancestors learned to detect the color red more easily. In this way, they could locate the mature fruit much fast. These elements were essential to their survival.

Many ancient cultures also placed great emphasis on highlighting people’s lips. That was especially true in the case of women’s lips.

That’s why many of them developed methods to “evert” their lips. In other words, shaped outward. These kinds of lips were redder.

That suggests that ancient cultures made an association between lips and survival. This particular example supports the hypothesis about instinct.

the anatomy of a kiss

When we kiss someone, we exchange about 40,000 microorganisms. The kiss stimulates saliva production which momentarily improves your breath.

Researchers have proved that people who kiss their significant other in the morning get sick less. They also have fewer traffic accidents and live up to five years longer. 

There are many aspects of the kiss that we have yet to understand. But… we can say that the anatomy of a kiss contains wonderful mysteries that have to do with happiness and life.