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Good Question: Why Do We Kiss To Show Affection?

MINNEAPOLIS (WCCO) - This Valentine's Day, you'll probably be doing a little smooching.

One study finds more than half of all couples kiss several times a week and 70 percent of us have regular make-out sessions.

But why do we swap saliva to show someone we love them? Why do we kiss? Good Question.

"The short answer is we don't know," said Michael Wilson, an anthropologist at the University of Minnesota. "But there are a bunch of different hypotheses for it."

One theory suggests kissing started with mothers chewing their food and passing it to their babies. A second hypothesis is kissing was one way to size up the health of a potential mate. There may have been some cues in a person's saliva about their genetic qualities.

"It wasn't romantic back then -- it was about survival," said Andrea Demirjian, author of Kissing – Everything You Wanted to Know About Life's Sweetest Pleasures.

Wilson believes kissing is a learned behavior, rather than an instinctive one. He points to new research suggesting that only 40 percent of cultures kiss to show affection. Those researchers speculate that the advent of better hygiene and dental care, as well as the rise of social classes, might have contributed to this practice.

"That's the way to signal to the world, 'I am a refined, sophisticated person from a cultured society,'" Wilson said.

Demirjian also pointed out there are an exceptional number of nerve endings in our mouth and lip area that send signals of happiness and arousal to our brains.

"It's a very sensual part of our bodies," said one woman who had been married 58 years. "That's probably why we do it."

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