The Science of Kissing: What Our Lips Are Telling Us

no title has been provided for this book
Category: Relationships
Genre: Self-Help
Published: 1/5/2011
When did humans begin to kiss? Why is kissing integral to some cultures and alien to others? Do good kissers make the best lovers? And is that expensive lip-plumping gloss worth it? Sheril Kirshenbaum, a biologist and science journalist, tackles these questions and more in The Science of a Kiss. It's everything you always wanted to know about kissing but either haven't asked, couldn't find out, or didn't realize you should understand.

Book Summary - The Science of Kissing by Sheril Kirshenbaum

Key Insights

When we experience our first romantic kiss, most likely as a teenager or a young adult, the specific mechanics of our happily locking lips are unlikely to be at the forefront of our minds. Instead, we are probably focusing on the new sensations we are encountering and the romantic feelings that are starting to emerge.

But, what if we knew more about what was really happening when we kissed another person? Would a better understanding of how things were occurring ‘behind the scenes’ lead to higher quality smooches later on?

Sheril Kirshenbaum, the author of The Science of Kissing, postulates that humans can indeed become more competent kissers if they challenge themselves to learn about the historical foundations of smacking lips. We also must value the physiological purposes and implications of what we-- humans and many other animals alike--feel naturally compelled to experience when we encounter the primal pull of attraction.

Key Points

Love and Trust

After we are born, we quickly become acclimated to being nursed by our mothers. It is through this initial mother-child bonding that babies become comfortable using their lips. In addition to nursing, babies use their lips for self-soothing activities, such as when they suck their thumbs. Even the act of nursing itself is relaxing for babies and makes them feel loved.

In fact, centuries ago, mothers took the use of lips with their babies a step further, often participating in premastication or the process of feeding mouth-to-mouth. While this might sound gross to contemporary moms, women used to lack the ability to have their babies’ food mashed mechanically, so premastication served as a transitional step between breastfeeding and solid food.

To this day, premastication is employed by many different animals, including apes and birds. In some cultures, it is still a practice that is implemented by humans as well. Premastication not only increases a baby’s attachment to their mother, but it also strengthens a child’s emotional foundation for the kissing that is likely to occur later in life.

A recent study found that in modern Egypt, more than 39 out of 119 communities still utilize premastication, which can also be effective in warding off illness.

Social Purposes

While we most often think of kissing as a precursor to--or a piece of--sexual activity, there are actually social reasons behind it as well.

In the Middle Ages, you would kiss people in different places depending on their social status. For instance, if you were greeting a priest, you would kiss his cloth and if you were greeting the Pope, you would kiss his slippers or ring. When you were kissing the ground, that usually meant that you were greeting a King.

Similar to the way that we use ‘x’s’ to represent kisses when we are typing out messages on a computer, the letter ‘x’ used to be found on contracts so that they could be signed by way of a kiss. Even now, you will often see an x in front of a signature line on most formal documents.

Almost every animal species has a behavior that mirrors kissing, be it nuzzling, sniffing, nibbling, licking, or caressing. Some of the ways that animals show affection are a bit unusual, such as the way that moles rub their noses, turtles tap each other’s hearts, and porcupines nuzzle. Bonobos are the most like humans in that they kiss with lips and tongues!

Ultimately, kissing allows for the exchange of information between two parties. And this information can vary quite a bit. The way that we kiss a family member is likely going to convey a very different message from what we would pass along to a potential mate.

Kissing signifies trust and acceptance. You are trusting someone enough to invite them to enter your personal space and you are also allowing your tastes and smells to co-mingle!

Compatibility Testing

At some point, in order to determine if you and a potential mate were destined to be together, you may have referred to an online compatibility quiz or even looked to astrological signs. However, determining compatibility can actually be as simple as paying careful attention to a kiss.

When we kiss another person, we are also smelling them and not just their mouth. Every human has scent glands on their armpits, neck, face, and genital area.

So, what makes for an attractive scent?

One that is different from our own.

We are biologically more likely to produce healthy babies with an individual who is immunologically dissimilar from us.

In our immune systems, we have something called MHC genes, which help us to differentiate our own cells from foreign cells. The more diverse these genes are, the more likely we are to have healthy immune systems.

Your MHC genes come from your parents and so when they differ, they produce stronger offspring. We naturally prefer people who have different MHC genes from us, thus indicating that our children would likely maintain good health.

In a recent study, heterosexual women were asked to select shirts based on which smells they were attracted to. Overwhelmingly, they picked shirts from men with significantly different MHC genes from their own. This is why you don’t kiss your brother the same way you would kiss your boyfriend--the MHC genes between you and a sibling are biologically similar, which creates a familial effect.

Kissing High

You might not consider yourself a drug user, but have you ever tried kissing? If so, you have likely experienced a high that is similar to what you feel from cocaine.

When you kiss another person, your brain experiences an adrenaline boost which leads to an increased heart rate and an energy spike, to boot. In addition to adrenaline, kissing produces serotonin and dopamine, the combination thereof making you feel relaxed and euphoric.

Cocaine and kissing literally stimulate the same regions of your brain, so it should not be surprising to hear that you can actually be addicted to kissing.

Your body also releases a bonding hormone during kissing, which automatically decreases your level of stress. See? Kissing is good for your heart!

This bonding hormone is called oxytocin and it strengthens emotional attachments. It is also responsible for the pleasure you feel when having an orgasm. During an orgasm, both men and women produce five times as much oxytocin as they normally would.

When you kiss, you are decreasing your cortisol levels, which weaken your immune system and can be harmful to your blood pressure. High levels of cortisol are associated with many diseases, so decreasing this particular hormone is one of the many physical benefits of kissing!

Lust, Attraction, and Attachment

We know, inherently, that kissing makes us feel good, but it is time we consider the reason why.

The answer is biological.

When we kiss, we are stimulating our limbic system by way of the very sensitive nerve endings on our lips. The limbic system is the portion of our brain that is most associated with love, passion, and lust.

However, in spite of the parallel limbic responses, men and women actually use kissing for very different purposes.

For women, kissing is often a test to see if sex with another person is an option or not. A study found that one out of eight women would not have sex with someone they had not first kissed. There might not be a moment where you consciously say, “Okay, if I don’t like this kiss, I am not going to have sex with this person.” Rather, you have biologically evolved to be less attracted to an individual whose kissing style does not complement your own.

Men, on the other hand, use kissing differently. Rather than determining the suitability of a mate, men use kissing to increase the chances of another person having sex with them. They attempt to elevate their odds by kissing with a large amount of tongue. Tongues transfer more testosterone to the woman or partner, which can be perceived as a sign of dominance.

Throughout history, there have been several attempts at banning kissing on moral or health-related grounds. For instance, during the Great Plague in London in 1965, governments banned kissing in order to slow the spread of the disease. It is unclear how effective this proved to be.

In 2008, South Africa attempted to ban kissing in children under 16 in a misguided approach to curbing HIV.

In many instances throughout history, the Catholic Church has tried to ban kissing on the grounds that it can potentially lead to sex.

The Main Take-away

We may take the power of a single kiss for granted in our day-to-day lives, but the reality is that the physiological changes brought on by locking lips can be incredibly beneficial to our physical and emotional health.

When we have a thorough understanding of the biological and evolutionary implications of this age-old ritual, we are able to use this foundation as a narrative for how and why we kiss the way we do.

In a broader context, kissing allows us to experience a deep form of attachment that is tied not just to human communities, but to the animal world as well.

About the Author

Sheril Kirshenbaum was born on May 24, 1980. After attending Tufts University and the University of Maine, she began her career as a science writer, author, and policy advocate. Currently, Kirshenbaum serves as the executive director of the Science Debate, an organization aimed at integrating science and politics.

In addition to The Science of Kissing, Kirshenbaum co-authored a book with writer Chris Mooney, titled Unscientific America: How Scientific Illiteracy Threatens our Future.

Kirshenbaum lives in East Lansing, Michigan with her husband David Lowry and sons.


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