Kissing is something that we do often, but seldom truly think about. Scientists believe that kissing evolved as a way of evaluating potential mates in our ancient ancestors (an extreme close-up, after all, reveals a lot more than a coy glance across the cave). By becoming so close to your partner that your faces actually touch, you are opening your body language up, saying without words “I trust you on a subconscious level, enough to let you get this close without being guarded about it.”
