If you think about it, kissing is pretty strange. You'd never walk up to your partner and purposely spit in his or her mouth, but essentially that's what we're doing when we kiss.
How much spit are we talking? The American Journal of Medicine estimates around 9 milliliters and as many as 10 million to 9 billion bacteria, depending on how long you're locking lips. But when we're making out with someone, we're not thinking about that because we're caught up in all of the feels.
Why does the act of swapping bacteria and bodily fluids feel so good?
Why do we kiss the people to whom we're attracted? Is it an act of nature or nurture? And what impact does it have on our relationships, both our romantic ones and platonic ones? If you've ever found your stomach full of butterflies during an intense make-out session and wondered what was going on behind the scenes, we've got answers.
Here's a look at the science of kissing.
Why Do We Kiss?
Regarding how or why we kiss, psychotherapist Dr. Tina B. Tessina says culture and upbringing play a role. "As an act of intimacy, kissing is an act of nature (instinct), but nurture (culture) can change when and how we kiss, such as the Inuit intimate act of rubbing noses (because connecting moist lips in freezing weather is problematic)," she explains. "Some cultures kiss a lot, on both cheeks or on the lips, within families or as a social act or greeting, and others kiss only romantically. Kissing as most of us know it is driven by the desire to get close to one another."
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Ever wonder why it feels extra good to kiss some potential partners, but not others? Sex educator Colby Marie Zongol says that's your pheromones at work. "The evolutionary theory behind kissing indicates that kissing is subconsciously used to determine mate compatibility," she explains. "Pheromones are exchanged through saliva during kissing, and we are innately attracted to others whose pheromones subconsciously communicate genetic compatibility for a mate. In other words, if you share a kiss with someone whose genetic makeup is compatible to your genetic makeup (aka is likely to create offspring with a high chance of survival), you are more likely to feel those butterflies when we kiss. If someone is not genetically compatible, we don't feel those butterflies."
What Happens When We Kiss?
As it turns out, the act of kissing a partner feels good because it triggers a release of the chemicals in our body responsible for pleasure. "Research has shown increases in the hormones oxytocin and dopamine during lip-locking," Zongol explains. "Oxytocin is linked to feelings of closeness and sexual desire, so those feelings typically increase as a result of kissing. Dopamine is the hormone that makes us feel happy, increasing our levels of pleasure during and after a kissing session." If you've ever finished kissing your partner and found that you felt less stressed than beforehand, there's a reason for that. "Further, the stress hormone Cortisol decreases, which typically leads to kissers feeling more relaxed," Zongol says.
How Kissing Improves Our Relationships
Aside from the fact that kissing feels good, Tessina points out that it also has many benefits for your relationship. "Kissing is a signal to each other of affection or love," she says. "It’s a reminder to a partner that we care about them. Long kissing gets us in the mood for sex, emotionally and physically. A brief kiss is a reassuring way to say hello or goodbye or to communicate warm feelings at any time. It’s more intimate than a hug."
Kissing can also be beneficial for strengthening our platonic relationships when applied in the right context. "Families and friends who kiss on cheeks are saying 'I love you' in a nonverbal way," she says. "Difficulties can arise when you get close to someone who has a different cultural definition of family kissing. For example, when a French person who is apt to be used to kissing on both cheeks as a form of greeting meets an American who isn’t used to that, it can be awkward. We have to learn those different cultural signals and not assume our own way is the 'right' way."
How To Be A “Good” Kisser
When it comes to being a good kisser, Tessina says the ability to tweak your technique to fit what your partner likes is key. "Kissing is quite subjective, but lovers learn to modify their kissing technique to suit each other’s preferences," she explains. "For example, some people like wet kisses, or using a lot of tongue, and others don’t like it, or have to work up to it. Talking with a partner about what you like and don’t like about kissing can improve your sex life." For those who are in a relationship that's fairly new, Tessina recommends taking it slow to learn his or her preferences. "Basically, if you’re kissing someone new, you should not dive right in, but start gently and tentatively, and find out what this new partner responds to," she says. "Kisses should build as each partner gives signals in the kiss, and responds to what the other partner is doing."