Your lips swell, and you get that pleasant tingling sensation in your private parts. The blood rushing to your skin's surface makes you feel fevered, your face flushed. You may begin to sweat. This ritual is what anthropologists call pre-copulatory activity, what sex manuals call foreplay and what Marvin Gaye calls getting it on. And getting it on is good for your health.
Doctors believe that physical touch itself boosts levels of the hormone oxytocin.
Among other things, oxytocin boosts feelings of affection and promotes caretaking behavior, and synthetic oxytocin has been used to treat depression. It takes only two muscles to purse your lips into a simple pucker, but a serious French kiss activates all 34 of your facial muscles, and the highest level of serious making out, properly done, engages every muscle and tendon in your body. She kissed the hurt away. The chaste, nurturing kisses between parent and child build lifelong trust. It's better than medication at times.