Scientists suspect that when a couple who carry distinctly different genetics for fighting disease, their children are likely to benefit by having a strong immune system. We may not exactly be thinking about parenthood when we connect with someone at the lips, but kissing provides clues to help us decide whether to take a relationship further. (However, it’s important to add that women who take the birth control pill show the opposite preference toward men with MHC genetics most like their own. This suggests that when we are on contraceptives, we may be fooling our bodies in more ways than we realize.)
Getting hot under the collar
Aside from helping us find a great match, kissing has other perks as well. It sets off a cascade of neural impulses that bounce between the brain and the tongue, lips, facial muscles, and skin. Billions of little nerve connections distribute information around the body, producing chemical signals that change the way we feel.
A passionate kiss can spike the neurotransmitter dopamine, which is linked to feelings of craving and desire. Oxytocin, known as the “love hormone,” fosters a sense of closeness and attachment. Adrenaline boosts our heart rate and can make us start sweating as our bodies begin to anticipate what might occur later. Cortisol, known as the stress hormone, also dips to reduce uneasiness. Blood vessels dilate, breathing can deepen, cheeks flush and our pulse quickens.
Kissing fosters the sensations we often describe when we are falling in love. In this way, a kiss can herald in a new romantic relationship. It can also solidify the strong bonds we share with family members and friends. Kisses come in many varieties and are inherently tied to the most meaningful and significant moments of our lives by providing a means to communicate beyond what words can convey.
Science has barely begun to study kissing, despite its obvious evolutionary and personal significance, but what we already know demonstrates that there’s a lot more to going on than meets the eyes – and lips.