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The science of smooching

Studies show men and women respond to kissing differently: Women can use it to assess a mate's health, men to end a quarrel

By Jason George | Tribune reporter

7:12 PM CST, February 14, 2009

Illinois Tech attempted to measure the sparks exchanged in a kiss with an electrical kiss-o-meter in May 1948. (Tribune archive photo / January 6, 2009)

If you kiss your sweetheart this Valentine's Day and find it especially appealing, credit the candlelight, the champagne—or maybe just excellent gene compatibility.

"[Kissing] is not just for fun and sexuality. You are passing vital information about who you are—your genetics, your temperament," said Dr. Helen Fisher, a biological anthropologist at Rutgers University. "When you kiss you're not just picking up if they're a nice guy, you're picking up if he'll be a good father."

Fisher knows all this from studying human brain activity, and she'll discuss her research at this weekend's annual meeting of the American Association for the Advancement of Science, at the Hyatt Regency Chicago. There, she will join other academics in presenting their most recent findings at a symposium titled "The Science of Kissing," the first association conference on the topic.

"Kissing is so common, but we know very little about it," said Wendy Hill, a professor of neurology at Lafayette College, who's also scheduled to speak.

"Kissing is just the tip of the iceberg of understanding all of the biological mechanisms that are involved for mate choice," added Fisher, who is also the chief scientific adviser to the Internet dating site Chemistry.com.

Academic interest in philematology, or the science of kissing, increases each year—thanks to technological improvements in genetics research and neurology—but lip-locking for love is of course nothing new: Kissing occurs in at least 90 percent of the world's cultures, and romantic puckering probably predates recorded history.

"There's also political, power and social kissing all throughout antiquity," said Donald Lateiner, professor of humanities-classics at Ohio Wesleyan University.

"The Greeks seem to have kissed less than the Romans, not that I have the videotape or Kinsey Institute of Rome to reference.

"We see the escalation of osculation"—that's the rise of kissing—"through the art we find," said Lateiner, who also is scheduled to speak at this weekend's conference.

While the Greeks and Romans might have differed on how often they kissed, such differences are not unique. Men and women also approach the act differently, according to several recent studies. For example, one found that women use kissing to assess a mate's health and maintain a relationship; in contrast, men place less importance on kissing and are more likely to use it to end a lovers quarrel or increase the likelihood of having sex.

Men are also twice as likely as women to have sex with a bad kisser, according to the same study, written by professors Susan Hughes, Marissa Harrison and Gordon Gallup Jr.

"[These] results suggest that kissing may play an important role as an adaptive courtship/mating ritual," the authors wrote in the online journal Evolutionary Psychology in 2007.

Furthermore, it's not the lips that deserve most of the credit for why we kiss. The brain does much of the heavy lifting, and new technology is allowing scientists to examine this better. For example, the neurology research of Dr. Vilayanur Ramachandran of the University of California at San Diego, another speaker at this weekend's event, suggests that kissing stimulates mirror neurons in the brain that promote empathy and reduce inhibitions.

In other words, kissing truly could be the language of love.

At Pennsylvania's Lafayette College, Hill, the neurology professor, is studying the chemicals that the body releases—and exchanges—when couples kiss, such as the stress-related hormone cortisol and the bonding-related chemical oxytocin.

"We think [kissing] has stress-reducing properties at least for those couples who are in committed relationships," said Evan Lebovitz, a senior neuroscience major who is Hill's assistant.

How did they determine this?

Hill and her team split a group of college-age couples into two groups: Members of one kissed for 15 minutes, and the others conversed without physical contact. She took blood and saliva samples before and after the sessions.

While getting college-age couples to kiss doesn't sound like a tough task, Hill didn't take any chances and turned part of the school's neuroscience building into a love den; the team lit candles, hung drapes and soothed the students by playing smooth jazz.

"Our earlier experiments were in the health center, and we wanted to provide a more relaxing environment," Hill said. "We're learning as we go."

Lebovitz said the students also preferred the new setting, although some of the young lovers were unhappy with the group they were assigned.

"Some people were disappointed that they were in the talking group, that's for sure," he said.

"We had one couple that said they didn't think they could talk for 15 minutes."

jageorge@tribune.com