What’s in a kiss?
July 18th, 2008
You gaze into his or her eyes. Your breathing deepens. Your pupils dilate. Your ribcage can’t hold back the drumming of your heart. You lean close. His or her breath warms your lips. You’ve crossed the threshold. There’s no turning back. Reason slides into retreat. What’s left but to surrender. Casanova proclaimed, “I don’t conquer, I submit.”
What’s in a kiss? The thinnest layers of skin. Moreover, the lips, together with the tongue, enjoy more sensory neurons per square centimeter than anywhere else on the body. Those neurons trigger an intoxicating cocktail of densely packed sensation. To the brain, sensation is information – texture, temperature, taste, smell. Who is this man? Who is this woman?
If you were to scan the brains of two lovers gazing into each other’s eyes you’d find a flurry of neuronal firing in the right ventral tegmental area and the right caudate nucleus. These areas are central to the brain’s reward centers — the same centers jacked up by cocaine. Add a kiss? Love is the drug, indeed.
Love is the Drug, Roxy Music
Evolutionary psychologist Gordon G. Gallup has theorized that kissing conveys subconscious information about a prospective mate’s genetic compatibility. (1) This information passes beneath our awareness through the tactile (touch) and olfactory (smell) sensory systems. Now here’s where evolutionary theorists often step onto thin ice, even ones who should know better. And here’s where throughout human history bazillions of the love struck have fallen into heartbreak’s abyss. Genetic compatibility doesn’t insure a great partner any more than does great kissing.
Genes don’t “care” whether that man or woman you’re smooching will be that hall-of- fame mate or not. Genes are out to replicate themselves. The information gathered doesn’t have to be accurate, just good enough to get that job done. Our choices are always a gamble. Chance always lurks about life’s table. Our senses help us sort the odds. If his kiss is soft, wet, and passionate, maybe it shows he’s invested enough to stick around. Maybe. If her mouth melts and she slides her tongue against yours, maybe she’ll be yours. Maybe. We have to base our guesses on something. What’s closer to the scan of our senses than a kiss?
It may be, instead, that the information our brain tracks in those devouring lips helps us weed out the genetic misfits. It’s a more efficient evolutionarily strategy to let us in on what to avoid, than to show us what we are going for. Bad smell, disgusting taste, rough and nervously tight lips. (Evolutionarily, a high probability sign of poor health, weak temperament, and unfavorable genes.) It may be hard to be certain if he or she is that forever mate with great genes, but we certainly will tingle with delight over that good kisser, and shove ourselves off from the bad. For better and worse, for richer and poorer, and sometimes even in spite of all reason, most of us find ourselves playing the odds in favor of that pair of luscious, tasty, simmering lips.
___________________________________
(1) Walter, Chip. “Affairs of the Lips,” Scientific American Mind Vol. 19, No. 1 (2008): 24-29.