Valentine message: don't miss the kiss!

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You may call it love, but scientists call it philematology.

And according to experts in this field (yes, there are at least three of them), the 60's pop song got it right: It really is in his kiss.

"Kissing is a mechanism for mate choice and mate assessment," Helen Fisher, a Biological Anthropologist from Rutgers University here at the American Association for the Advancement of Science, said to a press conference crowded with science journalists hoping for a story or, perhaps, some advice.

Over 90 percent of human society engages in what, if you get right down to it, seems like a very strange thing to do: putting faces together and trading spit. But because it is so pervasive, scientists think there must be a good reason for it, some kind of evolutionary advantage. And humans aren't alone in this ritual. Chimpanzees kiss, foxes and dogs lick each other's faces, some birds tap their bills together, and elephants put their trunks in each other's mouths.

Humans have been kissing for ages. "Many kisses, particularly in the Roman novels, are slobbery," said Donald Lateiner of Ohio Wesleyan University in Delaware who studies the history of kissing. "Every time that the past is excavated at Pompeii, there is good a chance there will be some additional data on sexual customs, if not kissing."

So what's all the making out about? It may have to do with that elusive but essential ingredient to true love that we call chemistry. It turns out, it may not be that elusive after all. It may just actually be...chemistry.

Saliva is like a chemical cocktail, and hooking up may have evolved to help us quickly tell if someone is a good mate or not, Fisher said.

After all, haven't we all been attracted to someone and then the first kiss just killed it? It might be because he didn't have the right stuff in his spit. Lots of hormones are present in differing quantities in our saliva, and they may serve several romantic purposes.

"There's evidence that saliva has testosterone in it, and there's also evidence that men like sloppier kisses with more open mouth," Fisher said. "That suggests to me that they are unconsciously trying to transfer testosterone to trigger the sex drive in women."

This prompted one male reporter to ask, "Should I drool more when I kiss?"

"Are you suggesting men would be more successful if they passed more saliva?" he asked. "People will want to know that."

After Fisher first mistook "drool" said with an English accent for "drill" and asked if it was some sort of British kissing technique, she dodged the question saying she's not in the "should business," about what you should or shouldn't do.

But, she did offer the advice that "you don't want to turn your partner off."

And there may be more to this chemical assessment than just kissing, Fisher said. "I think kissing is the tip of the ice berg. I think we'll find that all kinds of other chemical systems are in play that we don't know about."

Fisher says she has found from other scientists' research and from her own analysis of statistics on 40,000 people on the dating Web site Chemistry.com that there are four dimensions of temperaments, or biologically based traits, and each is associated with different chemical systems in the brain: Dopamine is associated with traits like novelty seeking, risk taking, curiosity and creativity; serotonin was linked to calm, caution cooperation, loyalty, and tradition; testosterone with decisiveness and emotional containment; and estrogen lumped together with oxytocin was linked to nurturing, patience and social skills.

So Fisher devised a questionnaire and gave it to 28,000 people on Chemistry.com to see if how strongly people express each of these systems affects their partner choice.

"It now appears that we are drawn to people with particular biological profiles," she said. And the kiss may be how we assess someone's profile.

This drew the obvious question from a reporter: "Is it true that opposites attract?"

Well, that depends on the person she said. Those adventurous ones who express dopamine strongly preferred people like themselves, and the same was true for the more traditional, serotonin expressers. But those high in testosterone preferred more estrogen and vice versa.

But there has to be more to it than just pure chemical profiling, right?

Neuroscientist Wendy Hill thinks it also plays a role in pair bonding. Now doesn't that sound more romantic?

Maybe, but she studied this idea by asking college-aged couples to do the decidedly unromantic act of making out for 15 minutes in a lab room at the campus infirmary. By comparing blood and saliva samples from before and after the kissing sessions, she discovered that cortisol, a hormone involved in stress, went down in both men and women. Interestingly, kissing boosted the mens' level of oxytocin, which has been linked to pair bonding, but the level dropped slightly in women.

Hill suspects that despite the flowers and music she provided, this could be because the college health center is where the students go when they feel sick, not sexy, which may affect women more than men.

So Hill is currently running a similar study in a far more seductive setting...an academic building. Sounds romantic, right?

Though she hasn't yet analyzed the new oxytocin results, she thinks the couch, light Jazz CD, and electric candles (real candles are against Lafayette College fire regulations) will do the trick.

What other burning questions did journalists have for the philematology experts? Several of them wondered why people are obsessed with oral hygiene. I'm not sure what that says about journalists.