Why we kiss

Osculation is the scientific term for “kissing” but of course you never hear anyone refer to their first kiss as their first osculation unless you’re like Sheldon, the main character in the hit comedy series Big Bang Theory. But no matter what you call it — kissing or osculation — it refers to the act when your lips come in contact with another pair of lips or somebody else’s body part.

We know that humans kiss and we do kiss for various reasons. In fact, anthropologists are pretty confident to say that 90 percent of all human societies kiss. I am not sure what the other ten percent does, but after having read my share of scientific research on kissing through the years, I want to suggest to researchers to ask these societies why they do not kiss. Bonobos who also have pink lips like humans, also kiss another pair of lips, in fact for as long as 12 minutes. Other animals like some species of fish, lock lips. This has something to do with mating but scientists have also observed that they also kiss when in conflict so it is a tricky thing to say with certainty that the emotional meaning of a human kiss is the same in other animals.

Fish and Bonobo kisses are among the things that amused me as I listened to Ira Flatow of NPR.org’s Science Friday interview Sheril Kirshenbaum last Feb. 10. Kirshenbaum is the author of a book called “The Science of Kissing” (Grand Central Publishing 2011) and she said that kissing is in so many ways good for us. She focused much more on the kiss between lovers understandably because it was Science Friday’s Valentine’s offering. On the romantic level, she said that research has found that kissing stimulates the release of a hormone called oxytocin, a chemical naturally released by humans that makes them feel affectionate and attached to the one they are kissing. This means that “kissing” is a means to keeping the relationship “warm.” She also mentioned a study that revealed how much men and women regarded “kisses,” surprising me by saying that 59 percent of men and 66 percent of women have dropped their relationships because of a bad first kiss. She also mentioned a gender difference in the role of kissing, citing that men viewed kissing more as a prelude to sex while women generally regarded kissing as an act in itself. No wonder more women dropped men who kissed them badly.

In a research published last 2009 by Helen Fisher, a prominent anthropologist who has done so much work on the science of love, discovered that a man’s saliva is filled with testosterone which could drive the sex drive of the woman he is kissing. This seems to have found proof in research published in the Journal Evolutionary Psychology that found that only 14 percent of women would want to have sex without being kissed. Kirshenbaum also elaborated that because of the intimacy of a kiss, the kissers get a good dose, including a deep sniff of each other’s natural chemicals which science has indeed proven to be what is at work when we choose mates. Experiments have shown that by sniffing, women preferred the scent of men whose immune system turned out to be so different from theirs. This is good because the farther your mate’s immune system is from yours, the better chances your offspring has of surviving and overcoming diseases that one of you pass on through your genes. Ergo, this makes kissing one of the behaviors that has helped us survive as a species. Kissing has helped us stay alive. 

Kirshenbaum said that the earliest known reference to a kiss is found in a Sanskrit text which is about 3,500 years old. I know that the earliest written code found in stone is about 6,000 years old and it was not about kissing but, well, about 10 goats. Modern human species have been here for far longer than that — at least 200,000 years and older, other species of humans, for about three million years. I do not think it is too far off to think that they must have discovered the wonders that lips unleash when it comes in contact with another, even then. Unfortunately, kisses do not fossilize so we may never know when it started. But we know we all enjoy it more than enough to keep it alive. So if there is any advice a Valentine-themed science column can give, I think there is only one: osculate. It’s good for you.

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