[There are many types of kisses but this post is dealing with romantic kisses.]
Here’s an article from eHarmony called Science of a First Kiss.
This basically sums up the biochemical aspect of kissing:
As one starts to kiss, the nerve endings in the lips become more sensitive. The stimulation causes these nerve endings to fire signals back to the brainâ€™s cortex to release neurotransmitters, including dopamine, endorphins, and phenylethylamine. Dopamine is largely responsible for feelings of pleasure and motivation to engage in pleasurable activities. Endorphins, which are peptides, are known to relieve pain in the body, but they can lead to feelings of euphoria as well. Phenylethylamine, an alkaloid also found in chocolate, is thought to influence mood and attention. When these neurotransmitters are released throughout the body, they result in sensations of happiness, giddiness, and euphoria. No wonder kissing feels so good.
I don’t know if most people think it kills the romance to know what’s going on behind the scenes… like knowing the secret to a magic trick. For me, my major was human biology with a concentration in the neurobiological basis of human behavior so I found the article fascinating.
In addition to revealing what happens during a great kiss, the article helps explain (implicitly) what doesn’t happen when kissing someone with whom there is no chemistry. That’s why a kiss is so telling. If a person one is kissing doesn’t induce the chemical reaction described in the article, that’s a pretty huge hint.