Why do we kiss?

Humans have been kissing one another for thousands of years. But is smooching more science than art, more biology than poetry?

“A man’s kiss is his signature.” — Mae West

“A man’s kiss is his signature.” — Mae West

“A man’s kiss is his signature.” — Mae West

There’s the romantic kiss, the social kiss, the air kiss, the kiss that conveys affection, familial ties or deep respect. The ancient Romans were big on romantic kissing, but the Greeks viewed kissing more as a way to pay homage or give social recognition. In Biblical times, washing and kissing another’s feet was considered a gesture of humility and respect. The Black Stone of Mecca, a relic considered holy by Muslims, has been polished smooth by centuries of kissing. Today, kissing is a near universal behavior, with many of us puckering up under the mistletoe, to seal a marriage and to ring in the New Year.

Humans have been kissing — for any number of reasons — for a very long time, according to scientists. But where did the custom come from and why exactly do we do it?