The Science of Kissing: What Our Lips Are Telling Us

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The Science of Kissing: What Our Lips Are Telling Us Page 11

by Sheril Kirshenbaum


  One virus you probably do not need to be concerned about when it comes to kissing is HIV. Although many people suffer from bleeding gums, the virus does not appear to be transmitted this way. It’s probably safe to kiss your partner passionately without first sending him or her to a clinic for analysis.

  To date, no one on record has become infected with HIV from kisses without tongue. Openmouthed kissing, meanwhile, is considered a low-risk activity by the Centers for Disease Control and Prevention (CDC), and there’s only one case where a woman apparently contracted HIV through her kissing partner’s contaminated blood. (The details in this case are unclear, and curiously, the man involved was reported as a “sexual partner” as well.) Still, the CDC warns against “prolonged open-mouth kissing” with someone known to carry HIV.

  Something else you needn’t worry about is locking braces: This appears to be an urban legend. Modern braces are smaller than they were in the past, and according to the American Association of Orthodontists, it is nearly impossible to get stuck to someone while kissing—braces, after all, are not magnetic.

  AND THEN there are the riskiest “kisses” of all. Fortunately, they are probably unfamiliar to most readers, since they involve going to extraordinarily dangerous extremes. Still, it’s important to survey the most unusual styles of “kissing” behavior that can lead to dire consequences.

  The recent rise of interest in vampires, particularly among teens, makes the practice of biting another person to draw their blood necessary to mention. In short, just don’t do it. Swapping saliva through traditional kissing is vastly safer than literally injecting gobs of potentially dangerous microorganisms directly into the bloodstream of your beloved. It’s probably the worst conceivable way to show someone you care, given that you’re exposing them to a potentially life-threatening situation.

  Many of the germs in our mouths are harmless until they break the skin barrier. In fact, doctors consider the human bite to be of greater concern than most snakebites and broken bones, and often send human bite victims straight to the emergency room. So remember the lesson from preschool and do not bite your loved ones for any reason. The outcome won’t be as sensual as it appears on film, and may require medical intervention.

  Along the same lines, it’s also inadvisable to make any kind of oral contact with the mouths of wild animals that could be carrying deadly diseases. In the summer of 2009, for instance, the Lee County Health Department in Florida and the CDC put out a search for three boys, aged ten to twelve years old, who had been seen “kissing” a dead rabid bat in Florida. Who knows what they were thinking, but they took a tremendous risk. There is no cure for rabies.

  Fortunately, the average person will not encounter these uniquely dangerous kinds of “kisses.” But there is one further risk that can truly put you in a life-or-death situation.

  You might think you’re out with the perfect person, about to embark on an epic romance. All the signals seem right, and you go in for the kiss. But suddenly, instead of being excited and aroused, you—or your partner—is covered with hives. Oscar Wilde once remarked, “A kiss may ruin a human life.” While I doubt he had peanut butter or split pea soup in mind, allergens can be a serious mood killer, or in extreme cases even a deadly poison.

  For the majority of us, this scenario has probably never crossed our minds. But food sensitivities can rear their ugly heads at the most inopportune time. The usual suspects are shellfish, eggs, and milk, but peanut allergies are the main cause of fatalities. In extreme cases, kissing has triggered an immediate anaphylactic reaction from contact with trace amounts of the substance on another person’s lips. Symptoms can develop quickly and without warning—including difficulty breathing, facial swelling, hives, a dangerous drop in blood pressure, shock, loss of consciousness, and sometimes death.

  A recent study published in the New England Journal of Medicine found that about 5 percent of people who are allergic to nuts or seeds reported experiencing adverse reactions from kissing. When seventeen volunteers consented to be kissed by someone who had just consumed their particular allergen, reactions occurred in under a minute, and involved itching and swelling. Some subjects experienced wheezing, and one required a shot of epinephrine in the emergency room. These results suggest that although kissing isn’t normally considered a life-threatening activity, food allergies do threaten a small percentage of the population—even after a partner has brushed his or her teeth.

  IF YOU’RE FEELING SQUEAMISH about puckering up at this point, you’re not alone. There’s an actual term, “philematophobia”: the fear of kissing, which occurs when someone comes to find lip-on-lip contact completely terrifying. Some people who suffer from this are most frightened of bacteria, while others fear having their tongues bitten off.

  Most of us, though, want to keep kissing—while protecting ourselves from potential disease. By any measure, an awareness of the risks described above is a key part of our defenses. Not only can cleanliness help defeat germs, but it also boosts the likelihood that another virus- and bacteria-laden mouth pressed to yours will be back for more.

  No matter how attractive someone may be, poor hygiene can kill the moment before it even begins. This is particularly true for men. As preceding chapters have described, women depend heavily on taste and smell and pay close attention to teeth when evaluating a partner.

  In this chapter, I’ve covered the disturbing, dirty, and allergic aspects of kissing. In the end, it certainly seems the practice can leave us exposed to some serious illnesses. Still, claims about “risk” mean nothing without context, and when it comes to kissing, the risks are relatively minor compared to other sexual and nonsexual activities. In reality, there are generally a greater number of dangerous germs transmitted during a handshake than a kiss.

  Furthermore, some noteworthy benefits to kissing should be balanced against concerns. For example, thinking about a desirable kiss stimulates the flow of your own saliva, bathing the mouth and dispersing plaque, which helps protect your teeth.

  And aside from improving our mood, being on a natural kissing high may also help us live longer. A ten-year psychology study undertaken in Germany during the 1980s found that men who kissed their wives before leaving for work lived, on average, five years longer, earning 20 to 30 percent more than peers who left without a peck good-bye. The researchers also reported that not kissing one’s wife before leaving in the morning increased the possibility of a car accident by 50 percent. Psychologists do not believe it’s the kiss itself that accounts for the difference but rather that kissers were likely to begin the day with a positive attitude, leading to a healthier lifestyle. Kissing, after all, has been proven to promote strong social bonds, which have been shown to foster health benefits and emotional well-being.

  So although kissing carries some risk, it also brings potential rewards. And no matter what the medical experts may discover, I have a feeling humans will keep at it for a very long time.

  The Blarney Stone

  In 2009, the travel website TripAdvisor.com dubbed the Blarney Stone in Cork, Ireland, the most “unhygienic” tourist attraction in the world.

  Why so disgusting? Every day, over a thousand visitors kiss the stone at Blarney Castle, which is purported to give people the gift of eloquent speech. To reach it, they must literally bend over backward and hang on to iron bars. Despite the trouble, up to 400,000 people press their lips to its surface each year. No doubt that’s a lot of germs, but TripAdvisor.com admits it has no scientific evidence to back the claim that it’s truly the germiest destination on earth.

  PART THREE

  Great Expectations

  Kisses are a better fate than wisdom.

  —e. e. cummings

  CHAPTER 10

  This Is Your Brain on Kissing

  One evening while I was researching this book, I found myself staring down a mountain of scientific articles related to kissing. And suddenly it occurred to me: Given how much I’d already learned about the subject, t
here must be a way to push existing knowledge a little bit further and make some new discoveries. After conducting a thorough search of the scientific literature on kissing, I knew very well what kind of research was already out there—including many of the studies discussed in the preceding pages. It wasn’t all that much compared to what exists in other scientific fields; you would think a near-universal behavior in our species might have garnered more attention. Still, there was no doubt that the science to date raised a lot of interesting—and testable—possibilities.

  For instance, if men and women have different hormonal responses to kissing (as shown in chapter 8), these changes would be intimately related to what’s going on in our brains during the behavior. After all, the brain controls the release of our hormones. So how would the response to a kiss appear when recorded using the latest brain imaging technology? Might we visualize differences between the sexes?

  As far as I could tell from my research, no one had yet studied kissing using a brain scanning device like a magnetoencephalography (MEG) machine, capable of picking up a far different kind of information than revealed by surveys or blood and saliva tests. Wondering how I might obtain access to such a machine, I called up a friend in neuroscience, Dr. David Poeppel, to find out if I could tear him away from his research at New York University long enough to begin a new investigation on kissing and the brain.

  And here’s the crazy part: He agreed.

  Poeppel is a cognitive neuroscientist who’s interested in the way our brains are involved in human hearing and speech, and how they store and perceive information. He’s also exploring the brain-to-computer interface: Might our thoughts be downloadable and transferable and even emailable, just like other bits of data? Just when you thought reading minds was pure science fiction, David is out to write the true story. (Don’t worry, though. Even if it is possible, he assures me that mind control would not be feasible for an extremely long time.)

  Poeppel has the kind of intense curiosity that makes for a great scientist, and on top of that he’s also very cool. He’s not the stereotypical scientist depicted by Hollywood as a socially awkward Rick Moranis character or an evildoer out to take over the world. Instead, David’s a funny, really nice family man with a great team of graduate students. He also happens to have access to several amazing and powerful brain scanning machines in his NYU laboratory.

  I’m not sure David knew what he was getting into when I initially contacted him, but he seemed keen to hear my ideas for the next steps in kissing experimentation. After a two-hour conversation, I bought tickets to fly several hundred miles up to his lab in New York City. We began laying out the methodology for a scientific study that, to the best of our knowledge, had never before been attempted—a cognitive neuroscience experiment on the effect of kissing in the brain.

  MAGNETOENCEPHALOGRAPHY provides a unique way of looking at how our brains work. Scientists call it a “brain imaging” technique, but what an MEG machine really does is measure the magnetic fields produced by the everyday electrical impulses in our brains. It allows scientists to watch brain activity as it happens, and study the direction and location of the impulses that are the basis for all our thoughts and actions, ranging from instinctive muscle movements to the release of various neurotransmitters. What’s more, MEG is noninvasive, meaning that we can see these magnetic fields—which reflect ongoing brain activity—without any surgery or risk to the research subject.

  An MEG machine is also a rare, expensive piece of hardware that runs several millions of dollars. There are only about ten or fifteen of them in the entire United States. But despite the cost, the machine is rather underwhelming in person. When you go inside its small magnetically shielded room to have your brain scanned, the table you have to lie down on doesn’t look much different from the standard examination table at the doctor’s office. Meanwhile, the place where you stick your head so that all this high-tech science can happen sort of resembles a toilet bowl. The walls of Poeppel’s MEG are constructed out of a special material called Mμ—an expensive mixture of metals with a high level of magnetic permeability. Mμ creates an environment that’s uniquely silent because it’s magnetically shielded from the outside world.

  If we were going to study kissing with this sophisticated and yet humble contraption, we would first have to get around an obvious practical problem: Two people can’t simultaneously squeeze their heads inside the machine’s “toilet” to make out. And even if they could, reading brain scans while subjects kissed would be nearly impossible, because they wouldn’t be holding still. Moreover, the context of the situation would be way too weird to extract any useful information. Cramped quarters, strange electrodes, and overlapping wires would undoubtedly skew the kissing experience. Just think of what a too-clinical hospital environment probably did to Hill and Wilson’s study of kissing and hormones, and multiply the effect dramatically.

  But in conversations with David, we soon thought of a way around this problem. One thing we could do with the MEG was show individual test subjects images of different couples kissing so as to evoke an observable brain response, and then measure it. In fact, this would introduce a new novelty into the experiment. As far as David knew, few MEG studies had looked at subjects’ responses to viewing two individuals doing something together (like kissing). Generally, human images used in past MEG studies had been simpler, such as displaying a single face.

  Now we had a good strategy—but the approach quickly raised another problem. Since science has no official taxonomy of kisses—i.e., no standard way to categorize all the different kinds—I would first need to establish one before we could show any kissing images to test subjects. Different kinds of kisses would surely evoke different brain responses; but we couldn’t measure them until we had decided precisely what kinds of kisses we wished to show.

  So after a good deal of thinking, and after remembering some kissing taxonomies from the Kama Sutra and from Roman times, I finally settled on three kissing “categories” to include:

  EROTIC KISS: passionate/sexually charged kiss

  FRIENDSHIP KISS: kiss between friends

  RELATIONSHIP KISS: affectionate kiss implying commitment

  As we’ve seen, there are many other types of kisses in the world. But collecting a range of images fitting these precise categories—and ensuring, at the same time, that the people in the images did not show major differences in age, race, or other attributes that might skew a subject’s responses—was more than enough work for a preliminary scientific run.

  For this early experiment, we also decided—in a fateful choice for what our results would ultimately show, though I didn’t know it then—that our three types of kisses would further vary according to three “conditions.” In addition to being either “erotic,” “friendship,” or “relationship” kisses, the kissing pairings in the images would be either male-female, female-female, or male-male. In the end, this meant that we would be scanning our test subjects’ brains to see how they responded to a total of nine different kinds of kisses, as follows:

  The Nine “Conditions” of the Kissing-MEG Experiment

  EROTIC

  Male-Female RELATIONSHIP

  Male-Female FRIENDSHIP

  Male-Female

  EROTIC

  Female-Female RELATIONSHIP

  Female-Female FRIENDSHIP

  Female-Female

  EROTIC

  Male-Male RELATIONSHIP

  Male-Male FRIENDSHIP

  Male-Male

  Finding photos to include in the study was not nearly as easy as it sounds. I began in the obvious way, by scouring the Internet for available images. Not surprisingly, a Google search for terms like “two women kissing” and “erotic kiss” led to all sorts of hits that weren’t particularly useful for my intended goal. I also received more than a few strange glances while I worked in North Carolina coffee shops.

  After sifting through far more pornography than I’d like to admit, I eventually located fiftee
n acceptable images whose kissing “category” seemed obvious. I then cropped the photos so they would show only the kissers’ heads—that way, their body positions or postures would not influence our test subjects’ responses. Furthermore, and to cut out other possible extraneous influences on the test subjects, I converted all the images from color to black-and-white.

  While I won’t show you here all of the different images used in the study, here is a good example of what one of the “conditions”—female-female relationship—might have looked like:

  PHOTO: ARIEL SOTO

  Sample image to represent

  “female-female committed relationship”

  And still, I wasn’t nearly finished setting the stage for our study of kissing in an MEG machine. For while I had my own interpretations of what each picture conveyed, and what kissing “category” it belonged to, I wanted to ensure that a suitably large consensus existed among other people as well. After all, perhaps my “erotic” kiss was someone else’s “relationship” kiss.

  Fortunately, the blog I write for Discover magazine attracts a fairly wide audience, so I developed a kissing survey for our readers. On June 8, 2009, I posted all fifteen images online, labeled by the letters A through O, and asked for readers’ help. They weren’t allowed to comment directly on the blog, because I didn’t want them to bias other readers’ responses. Rather, everyone interested in replying was asked to email privately with an assessment of each kiss: Was it “erotic,” “friendship,” or “committed relationship”?

 

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