IdeaFestival Peeps' Show: the Science of Kissing


A research scientist and regular "Convergence" columnist for Wired, Sheril Kirshenbaum recently wrote a book with the too-hard-to-ignore title of the "Science of Kissing: What Our Lips are Telling Us." We didn't. One of the many fascinating IdeaFestival 2011 presenters, she was kind enough to respond to a few questions about our favorite pastime, the subject of every middle school crush and the one memory none of us ever lose.

Penny White, where are you today?

The least expensive all-access passes of the year are now on sale for a limited time only. Buy one and come see Sheril, Leonard Mlodinow, Aubrey de Grey, the "other" Wes Moore and other leading thinkers and creatives at the IdeaFestival. Let us hear from your lips. Just mouth the word, "yes."


1) You write that the kiss is "our most intimate exchange". What has been historically exchanged besides pleasure?

Kissing has been as much a social custom as a romantic gesture and we have many examples in throughout history from the literature where kissing as a means of showing respect or even in supplication was practiced with no mention of romance.

Kissing has probably arisen and disappeared throughout human history or a variety of reasons in different parts of the world. The first literary evidence we have for the practice comes of India's Vedic Sanskrit texts, composed ~3500 years ago, but humans have likely been kissing, or engaging in similar behaviors for far longer given there are so many similar kissing-like behaviors throughout the animal kingdom.

2) Ingrid Bergman said that “A kiss is a lovely trick designed by nature to stop speech when words become superfluous.” How is this true or not true?

Kissing is the ultimate way to express how we feel beyond what words can convey. On top of that there are hidden signals that help each individual--particularly women who have a stronger sense of smell and taste--decide whether to pursue a deeper connection.

For example, kissing puts us in very close proximity to sample another person's natural odor and research has demonstrated that women are most attracted to the scent of men with a very different genetic code for immunity. We're not consciously aware of this, but a couple with diversity in this area may be more likely to have stronger, healthier children. In this way, a good kiss helps a woman figure out whether her partner would be a good long term match.

3) Why kiss on the lips? Why not just rub noses?

There are many theories about why we kiss the lips, but anthropologists and neuroscientists recognize that the color red gets noticed as an attractive and alluring signal. The social kiss also likely evolved from the sniff greeting bringing out faces into close proximity and over time a brush of the lips may have accompanied a brush of the nose. Our lips are also packed with sensitive nerve endings so even a slight brush will send a cascade of pleasurable signals to the brain encouraging us to continue under the right circumstances.

4) Why do men and women remember their first kisses so vividly?

It likely has to do with the fact that we are actively engaging all or our senses in the process. An enormous cascade of information is being sent around our bodies as we access our compatibility with the other person. Novelty alone has a huge effect on these chemicals in our brains, so a first kiss really leaves a very lasting impression. Additionally, vivid memories create the opportunity to spend time processing the experience later, enabling us to anticipate equally emotional experiences in the future.

5) Do men and women kiss for different reasons? If so, what are those reasons?

Men are more likely to describe kissing as a means to an end, as something that's done with hopes of sex down the line. Women tend to place more emphasis on the act of kissing itself in order to assess compatibility and relationship status. The good news is that it's enjoyable for both genders.

The human population is moving and networking faster than ever before, and kissing customs and opportunities continue to be in a state of flux to accommodate emerging technologies. There are now kissing-bots, virtual partners, and companion androids. However, no matter what kind of experiences become possible, the kiss as we know it will never go out of style because promotes an important connection.