When comedian Susan Prekel takes to the stage and spots an attractive man in the audience, her heart sinks. “By the end of my gig he's going to find me repulsive, at least as a sexual being,” she says.

In more than a decade of performing on the New York City comedy circuit, the attractive, tall brunette has been asked out only once after a show. But male comics get swarmed. “They do very well with women. I see it all the time,” Prekel says.

Comedians, it turns out, may simply be experiencing an extreme version of the typical romantic interplay between men and women. Although both genders consistently prefer a partner with a sense of humor, there is an intriguing discrepancy in how that preference plays out. Men want someone who will appreciate their jokes, and women want someone who makes them laugh. The complementary nature of these desires is no accident. Researchers suspect humor has deep evolutionary roots—in 1872 Charles Darwin noticed chimpanzees giggling as they played—and many argue that the laws of natural selection can help explain the complex senses of humor we have today.

Men and women use humor and laughter to attract one another and to signal romantic interest—but each gender accomplishes this in a different way. And as a relationship progresses, the way men and women use humor changes; it becomes a means of soothing one another and smoothing over rough patches. In fact, humor is rarely about anything funny at all; rather sharing a laugh can bring people closer together and even predict compatibility over the long haul.

Humor in all its forms—sarcastic, witty, anecdotal, ironic, satirical—is as complicated and evolved as language. It can be a weapon used to alienate and a means to communicate interest and intelligence. So at the risk of unweaving a rainbow, it's time to take a serious look at humor.

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Make Me Laugh
It was when scientists started watching men and women be funny, in addition to studying what people found funny, that interesting patterns emerged. “The literature prior to the 1990s focused on joke appreciation,” says Martin Lampert, humor expert and chair of social sciences at Holy Names University. “This was a contrived situation where subjects were presented with jokes and we documented their reaction.” Experiments then started to look at humor production, asking subjects to come up with jokes or studying how people amuse one another in the real world. “This gave us a much more accurate picture of what was happening,” Lampert says.

In 1996 Robert R. Provine, professor of psychology at the University of Maryland, analyzed 3,745 personal ads and found that women sought a mate who could make them laugh twice as often as they offered to return the favor. Men, on the other hand, offered humor about a third more than they requested it. These findings were the first big clue that the sexes were approaching humor from different angles.

Ten years later Eric R. Bressler of Westfield State College and Sigal Balshine of McMaster University revealed another intriguing gender difference. The psychologists showed 200 people photographs of men and women, each paired with either a funny or a fairly straight autobiographical statement. Women chose the funnier men as potential dates, but men showed no preference for the funny women (as Prekel, the comedian, has been witnessing in the real world). And yet all over the world, both sexes consistently rank a sense of humor as one of the most important traits in a mate—so why the disparity?

“Although both sexes say they want a sense of humor, in our research women interpreted this as ‘someone who makes me laugh,’ and men wanted ‘someone who laughs at my jokes,’ ” says Rod A. Martin of Western University, Canada. In 2006 Martin, along with Bressler and Balshine, asked 127 subjects to choose between pairs of potential partners for either a one-night stand, a date, a short-term relationship, a long-term relationship or friendship. In each pair one partner was described as receptive to the participant's humor but not very funny themselves, and the other partner was described as hilarious but not all that interested in the participant's own witty remarks.

In every context other than friendship, men preferred women who would laugh at their jokes to those who made jokes. Women, however, preferred partners who were funny.

The fact that a man and a woman complement each other when they offer and request humor is striking because laughter is not under our conscious control, Provine points out. And as with many behaviors that occur outside of our awareness, researchers suspect these opposing desires may have arisen because they serve a reproductive purpose.

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Why Funny Men Are So Attractive
From an evolutionary perspective, the sex that contributes more resources to the development of offspring will likely be the choosier of the two. In all mammals, that choosier sex is the female because of the burden of pregnancy. So the male must compete for female attention—think of the courtship displays of bucks with their grand antlers. When a female is drawn to an impressive performer, she is unknowingly responding to his genetic health—thereby increasing the likelihood that her offspring will survive.

This evolutionary force is referred to as sexual selection, and psychologist Scott Barry Kaufman of New York University thinks it may explain why humor is so important in early courtship and why men produce the jokes while women appreciate them. “Humor is pretty sexy at first meeting. When you have little else to go on, a witty person who uses humor in a clever, original way is signaling quite a lot of information, including intelligence, creativity, and even aspects of their personality such as playfulness and openness to experience,” says Kaufman, who has done studies on the role of creativity in humor.

Supporting this idea are studies that show that humor is a good indicator of intelligence—a highly prized, heritable trait. For instance, in 2008 Daniel Howrigan of the University of Colorado at Boulder asked nearly 200 people to create humorous statements and draw funny images. Those who scored higher on a test of general intelligence were also rated by observers as being significantly funnier.

A more subtle test of the sexual selection hypothesis for humor depends on what women want when they are at their most fertile—during ovulation. A large body of research has shown that when considering short-term partners, ovulating women tend to prefer men who have signs of good genes, such as body symmetry, masculine facial features and behavioral dominance. In contrast, when considering long-term partners at any point in their cycle, women show no preference, often choosing men with resources (in this day and age, that means money) and nurturing characteristics—in other words, good dads.

If humor is a sign of creativity and intelligence and hence an indicator of high-quality genes, funny guys should be highly desirable to women when they are ovulating. Although it did not focus specifically on humor, a 2006 study by Geoffrey Miller of the University of New Mexico and Martie Haselton of the University of California, Los Angeles, showed that ovulating women do indeed prefer men with creative intelligence. Forty-one women read descriptions of creative but poor men and uncreative but wealthy men and rated each man's desirability as a short-term mate. During high fertility, women chose creative men about twice as often as wealthy men for short-term pairing, but no preference emerged for creative men as long-term partners—exactly the pattern one would expect.

If being creative and funny is valuable in courtship, then making others guffaw should be a priority for guys. Think back on the class clowns you've known. Were they boys?

And while the boys were clowning, chances are the girls were giggling. Studies of laughter also reveal clues about humor's important, evolved role in courtship, as Provine discovered when he started studying spontaneous conversation in 1993. He had tried studying laughter in the laboratory, but plopping a person in front of a TV with a couple of Saturday Night Live episodes did not incite much hilarity. Provine came to the stark realization: laughter is inherently social. So he set out, like a field primatologist, to observe human interaction in urban spaces: malls, sidewalks, cafes. He made note of about 1,200 laugh episodes—comments that elicited a laugh from either the speaker or the listener—and figured out which gender laughs when.

The results may not come as a surprise. Women, in general, laugh a lot more than men, according to Provine's data—especially in mixed-sex groups. “Both men and women laugh more at men than at women,” Provine observes. This finding aligns with the idea that men are performing humor and women, the “selectors,” are appreciating it, but of course there are other possible explanations. Are women simply less discriminating when it comes to humor? Or are men the funnier gender?

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Cracking the Laughter Code
Recent research suggests these possibilities are unlikely. Men and women are consistently judged to be equally funny when they go head to head on humor production. For instance, in 2009 Kim Edwards, a Ph.D. student in psychology at the University of Western Ontario, asked men and women to come up with funny captions for single-frame cartoons. Both genders created an equal number of highly rated captions.

In humor appreciation, too, women and men are on equal footing. In 2005 psychiatrist Allan Reiss of Stanford University showed men and women 30 cartoons while scanning their brains. Both genders rated 24 of the cartoons as funny, and when asked to rank them in terms of how funny they were, the genders again agreed. In addition, men and women had very little difference in their response times to the jokes they liked.

Given the sexes' similar capacity for humor production and appreciation, the fact that women laugh more—and men are laughed at more—must have its roots in something other than simply who is being funny. In fact, Provine's data support this idea, too: 80 to 90 percent of the statements that elicited laughter in his field studies were not funny at all. Rather people laughed at banal phrases such as “I'll see you guys later!” or “I think I'm done.” His research also showed that people tend to laugh more when they are speaking as opposed to listening. Many studies have confirmed this finding, and experts believe that when a speaker laughs, it sets his or her audience at ease and facilitates social connections.

Provine found one notable exception to the rule that speakers laugh more than their audience, however: when a man is talking to a woman, the woman laughs more than the man. The difference is sizable: when Provine averaged laughter in two-person pairs, the speakers laughed 46 percent more than the person listening. When a woman was talking to another woman, she laughed 73 percent more than her interlocutor, but when a woman was in conversation with a man she produced 126 percent more laughter. Male speakers laughed less than female speakers, but they still laughed 25 percent more than their listeners when they were talking to other men. But in the specific circumstance where a man was talking to a woman, the men laughed 8 percent less than their partners.

The fact that women laugh so much when they are speaking to men—and they laugh more than men even when the men are doing the talking—suggests that there is some instinct at play. Perhaps it is a reflection of the female role as sexual selector, but whatever the roots may be of the female instinct to laugh around men, it works—men find women attractive when they laugh. Perhaps it is because laughter unconsciously signals interest and enjoyment.

Consider that chimpanzees utter laughlike sounds when they are being chased by other chimps, and as with human children, the one being chased is the one who laughs. For chimps playing, the panting laugh is a signal to the chaser that the play is fun and nonthreatening. The enjoyment might come from anticipation, as if the laughter is sending a message: I'm going to keep running, but it's going to be really fun when I get caught. Because women are the ones typically chased in courtship, could there be a link? “I think there's an interesting parallel there,” humor expert Martin says. “In both cases, the laughter is a signal of enjoyment and invitation to continue.”

Indeed, studies have shown that laughter is a powerful measurement of the level of attraction between two people. In 1990 psychologists Karl Grammer and Irenaus Eibl-Eibesfeldt of the Ludwig Boltzmann Institute for Urban Ethology in Vienna studied natural conversations in mixed-sex groups and measured the amount of laughter coming from men and women. Later on each individual self-reported how attracted they were to other members of the group. It turns out it is the amount of female laughter that accurately predicts the level of attraction between both partners. In other words, a woman laughs a lot when she is attracted to a man or when she senses a man's interest—and that laughter, in turn, might make her more attractive to him or signal that she welcomes his attention.

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Funny through the Years
As attraction transitions to a relationship, humor's role changes, but sharing a laugh is no less important. Many agree it is the connection that humor fosters that makes it so good for relationships, especially over the long term. Humor often becomes a private language between two people. A couple's in-joke can make a mundane or tense moment hilarious.

But here again, each gender's role is different—and interestingly, in some ways men and women change places. Unlike during courtship, when men are usually the humor producers and women are the appreciators, in long-term relationships it can sometimes be harmful for men to use humor. When women are the humorous partners, however, relationships tend to thrive.

Funny men are not necessarily a curse, of course, but in certain situations male humor might be dangerous. In 1997 psychologists Catherine Cohan of Pennsylvania State University and Thomas Bradbury of the University of California, Los Angeles, analyzed the marriages of 60 couples over an 18-month period, using data from self-reports and audiotaped conversations of the couples working through a specific marital issue. They found that in couples who had a major life stressor such as a death in the family or a lost job, the husband's use of humor during problem solving was a warning sign. These couples were more likely to wind up divorced or separated within 18 months than couples with a life stressor where the male did not use humor. This result may be about men knowing how and when to crack the tension with a joke. Timing is key. “Particularly with men's humor we see it used to avoid problems or serious conversations,” Martin says. “And if it's used aggressively—in a teasing or put-down way—or at an inappropriate time, it can be detrimental to the relationship.”

The idea that male humor might sometimes be bad for a relationship is supported by results from the Coping Humor Scale (CHS) test developed by Martin and psychologist Herbert Lefcourt of the University of Waterloo, which measures how much one uses humor to cope with life stress. They found in 1986 that men who score high on the CHS report less marital satisfaction than their peers who do not use humor as much to cope. They also discovered that men tend to use more disparaging forms of humor, directed at others, when coping with a tough situation. If this is the type of humor men are referring to when they take the CHS, Lefcourt notes, it might explain the lower relationship satisfaction.

Women, on the other hand, have been shown by many studies to often use self-deprecating humor, which may bring relief to a tense situation. [For more on types of humor each gender prefers, see box on page 71.] And the CHS study found that women who use more humor to cope reported greater marital satisfaction.

A recent physiological study may help explain why. Couples psychologist John Gottman of the Gottman Institute in Seattle analyzed 130 couples discussing their top three most problematic issues. Starting when they were newlyweds, couples came to Gottman's lab once a year for six years and had private discussions while Gottman measured their physiological responses, such as blood pressure and pulse, with a polygraph and electrocardiogram.

Gottman found that the reduction of the male's heart rate during these intense discussions was critical for a successful marriage (whereas the female's heart rate made no difference). Some men were good at soothing themselves, but the next best way to lower these husbands' heart rates was for their wives to crack a joke to relieve the tension. Couples in which the women deescalated the conflict in this way, according to Gottman, were more likely to have a stable marriage through at least the study's six years, as compared with couples in which the wives did not use humor.

As a relationship progresses, then, a man's humor becomes less important—perhaps even counterproductive in certain situations—whereas a woman's sense of humor becomes a blessing. During courtship, a man's wit attracts a woman, and her appreciative laughter, in turn, is attractive to him. But as commitment increases, the challenge becomes less about landing a mate and more about keeping one around. “Here it is more about sympathy and attunement to the other's feelings and perspectives,” Martin says. “The goal is less to entertain and impress and more to reduce interpersonal tensions, convey understanding, save face for oneself and one's partner. Women may be more skilled at these uses of humor.”

Of course, in real life men and women inhabit a wide spectrum, with far greater individual variation than is reflected in the trends that show up in the lab. Many people have traits that are the opposite of those normally associated with their sex. But in general, the way men and women use humor betrays its deeper purpose—to help us connect and bond with one another. A genuine laugh is one of the most honest ways to convey: I'm with you.