When you pressed your little lips to mine, that was then i understood
They taste like candy, brandy and wine, peaches, bananas and everything good
I love jam and no film flam, scratch that off my list
This ain’t no jam, the jam can scram
Baby! c’mon and knock me a kiss
These words are from the 1941 Louis Jordan hit, “Knock Me a Kiss.” A quick google search for just the word “kiss” yielded no less than 237 million hits, and that’s only in English. Poets have been writing about them, singers have been singing about them, and in well over 90 percent of the cultures studied by scientists, lovers have been giving them — for as long as anyone can remember. There’s even a scientific branch of study devoted to kissing — philematology.
We know several things about kissing. For one thing, women are more into it than men, and they’re much more likely to insist on kissing before sex. For another, the first kiss really is the make or break moment for a lot of potential partnerships. In one study, 59 percent of men and 66 percent of women reported that they felt less attracted to someone after the first kiss! In other words, it’s one thing for us to look at someone and feel attracted. It’s quite another to pass the kiss test.*
Kissing, in a very practical sense, is a taste and smell test. We know that human females tend to be sexually attracted to men with a different immune system makeup. (Remember, natural selection likes diversity!) Smell is one of the most ancient and relatively reliable indicators of health and immune response, and it still works today. Of course, women don’t consciously think “Hey, this guy’s got a poor immune system.” However, if you have ever spent time in a hospital or hospice environment, you know that illness and smell are powerfully linked in the human subconscious. There really is a “smell of death,” and there really is a “smell of health.” While we haven’t completely dissected the chemistry of it all, we have clearly demonstrated that women are unconsciously able to differntiate between males based on traits that are invisible to the conscious eye.
Pardon my diversion, but I need to spend a little time talking about the science of human love, and then we will return to “the kiss.” According to Helen Fisher, a prominent writer on the science of human love, there are three phases of love: Sexual attraction, romantic love, and attachment. Sex drive, of course, is the initial attractor, and the part of love most likely to produce new humans, which is the ultimate purpose of our genes (at least from the point of view of natural selection).
With humans, however, just getting together and having sex is not enough to ensure the survival of the offspring. This is where romantic love comes in. Our feelings of wanting to share the future with someone, and imagining walks on the beach, intimate evenings in hot tubs, and rose petals in the bubble bath on Valentine’s Day, are all part of the romantic drive. In essence, it’s what makes us want to commit to one person rather than keep looking for sex anywhere we can get it.
Once we’re together, it gets sticky. Raising children is hard, stressful work, and it takes as long as twenty years in some cases. Evolution had to give us something to help us stick together for that long because (as anyone who’s been married will tell you) the honeymoon really does end, and there’s nothing you can do to keep the initial level of romantic and sexual desire. This is where attraction comes in. When we are with someone romantically for long enough, we literally become addicted to them. Oxytocin, among other chemicals, is largely responsible for our attraction to other people and our feelings of love. When we suddenly lose the companionship and affection of our partner, we experience something that can easily be called physical withdrawal.
So, evolution has designed us with three different mechanisms for successful reproduction — it encourages us to have sex, it drives us to want to have sex with the same person repeatedly, and finally, it makes us chemically dependent on that person to prevent us from wanting to leave them. Maybe it’s not the most romantic way of putting it, but it is the reality of it. While I don’t recommend trotting out the science book and talking of oxytocin addiction over an anniversary dinner, I think understanding these steps can make us happier as people, and can help us make healthier decisions.
In any case, let’s return to the kiss. Perhaps one of the reasons we are so addicted to kisses is that they apparently serve a large role in all three phases of human love. In phase one, they are one of the primary tools used by both men and women to determine sexual compatibility. In the romantic phase, they are one of the primary tools for creating intimacy and trust, and for facilitating the attachment phase, in which we literally feel like we have to have them.
For anyone who’s experienced a relationship that’s fizzled, it’s easy to see that the kiss is a lie detector. How cliche is it to say that you can “feel it in the kiss” when someone no longer feels the same way towards you? Cliche, but true. By the same token, how many times have we felt magic in the first kiss, or known that it was “true love” by the way someone kissed us? Kisses are powerful tools for our genes. Lucky for us, they are also something that we pretty much all love to get and give. For once, evolution has given us something that feels good that’s also good for us.
Our lips and tongues are custom made for this work. While our backs, elbows, and calves have relatively little sensitivity, our lips and tongues can distinguish minute details about anything that touches them. While it would be impossible for you to tell anything about the state of a lover’s lips by feeling them on your elbow, your lips can detect the slightest patch of dead skin, the smallest canker sore, or the faintest trace of unhealthy mucus from a cold. Fortuitously, they can also gain pleasure from healthy full lips as well. A very large part of the somatosensory cortex, which extends to both sides of the brain, is involved in receiving and processing information from the lips, nose, and tongue — the three parts of our face most involved in the kiss. So, for whatever else a kiss might be, it is certainly a functional part of our evolutionary heritage, and isn’t it wonderful that it is something we also love to do!
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*Are any of my cynical readers noticing that men who are looking for casual sex would do well not to put too much effort into kissing? If they can find a woman who doesn’t require a pre-sex kiss, they can skip a step that is very likely to reduce the chance that she’ll want to have sex with him! Isn’t science a real kick in the teeth sometimes?