Scientists in the Netherlands have reported that we share about 80m bacteria during a passionate 10-second kiss: a finding that makes puckering up seem cringe-worthy – and downright unsanitary.
But take heart: we’re more likely to get sick by shaking hands throughout the day than through kissing. And the science behind this behaviour reveals that along with all of those germs, we share plenty of benefits with a partner as well.
Kissing is not all about bacterial exchange or romance. Our first experiences with love and security usually involve lip pressure and stimulation through behaviours that mimic kissing, like nursing or bottle feeding. These early events lay down important neural pathways in a baby’s brain that associate kissing with positive emotions that continue to be important throughout life.
Our lips are the body’s most exposed erogenous zone. Unlike in other animals, human lips are everted, meaning they purse outward. They are packed with nerve endings so even the slightest brush sends a cascade of information to our brains, which can feel very good.
Kissing activates a very large part of the brain associated with sensory information because we’re at work making sense of the experience in order to decide what to do next. Kisses work their magic by setting off a whirlwind of neurotransmitters and hormones through our bodies that influence how we think and feel.
If there’s real “chemistry” between two people, a kiss can set the stage for a new romance. A passionate kiss puts two people in very close proximity – nose to nose. We learn about each other by engaging our sense of smell, our taste buds and sense of touch. And through that information all sorts of signals are being sent to our brain informing us about the other person. In fact, the scent of man can provide subconscious clues about his DNA to his partner.
Evolutionary psychologists at the State University of New York at Albany found that 59% of men and 66% of women say they have ended a budding relationship because a kiss didn’t go well. It’s nature’s ultimate litmus test, nudging us to be most attracted to the people who may be the best genetic partners.
Research by Swiss biologist Claus Wedekind found that women are most attracted to the scents of men who carry a different genetic code for their immune system in a region of DNA known as the major histocompatibility complex, or MHC. Scientists suspect that when a couple carry distinctly different genetics for fighting disease, their children are likely to benefit by having a strong immune system. We may not exactly be thinking about parenthood when we connect with someone at the lips, but kissing provides clues to help us decide whether to take a relationship further.
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