Searching through the New York Public Library's online catalog for books on friendship between men and women, I expected to find a wealth of titles, but when I entered my first keyword phrase, "male-female friendship," the system asked me if I meant "female friendship." "Cross-gender friendship" yielded "frost and friendship" (meaning the poet). Next I went with "man-woman friendships," which led, bizarrely, to "my animal friendships." (Or maybe not so bizarrely: Men recognized the virtues of canine companionship long before they came around to women.) "Cross-sex friendship," the term of art used by psychologists, turned up "profane friendship."

There's been astonishingly little work done on cross-sex friendship in any field, and the work that has been done is mostly inward-looking—how men and women feel about these relationships and how they manage them rather than what these relationships might mean for society. In trying to piece the latter together, I've wondered if the substitution of profane for cross-sex is unwittingly astute.

Certainly the Inquisition felt that a woman who pals around with her confessor somehow desecrates a sacred relationship by evening it out. The "Dear Prudence" commenter who wrote that "[S]haring a hotel room with an 'old friend' of the opposite sex simply isn't appropriate for people who are in committed relationships with each other" was making a similar argument: It's not kosher to maintain a cross-sex friendship and a romance at the same time. And by suggesting that male-female friendship is impossible, Hollywood sends the message that the relationship is taboo: It doesn't exist because it must not exist.




What's behind this impulse to deny male-female friendships—or to thwart them? Before the 20th century, when the chief obstacle to cross-sex friendship was a structurally unequal society, it's fairly obvious why non-romantic relationships between men and women made people uncomfortable: They put the lie to the idea that women have nothing to offer men outside of their traditional responsibilities (sex and child rearing). Michel de Montaigne cautioned in 1580 that women are not "firm enough to endure the strain of so tight and durable a knot" as friendship. If they really are "firm enough," though, who knows what else they might be capable of doing?

This conservative anxiety is still very much in evidence in certain parts of the world. A 2008 New York Times article on young Saudis from the nation's capital, Riyadh, notes that unmarried men cannot enter malls where women shop and that getting caught with an unrelated woman (in a completely innocent situation) can mean arrest and flogging. Even wedding ceremonies are separated by sex. Naturally a system exists to make weddings possible—arrangements between families, matchmakers—but there is no chance whatsoever for unrelated young men and women to meet as friends.

In the more level West, where the top-down barriers to friendship between the sexes have fallen away, the emphasis has shifted to undermining platonic relationships by suggesting that they're actually frustrated romances. Could the current objection to male-female friendship be an outgrowth of the older one? Maybe the "sex problem" is just another way of talking about how men and women are hopelessly different, hopelessly at odds.

Today it's no longer acceptable to suggest (publicly) that men and women aren't equal, but it's perfectly OK and even fashionable to state that we're equal but separate—that our brains work in fundamentally different ways, that we communicate differently, that we're metaphorically from different planets (Mars and Venus). The gender-war evangelists make men and women seem so far apart, so incompatible, you'd think that, if it weren't for the biological imperative to reproduce, men and women would want absolutely nothing to do with each other. This take on human relations serves as the basis for nearly every joke in the long-running TV series Everybody Loves Raymond, most Tyler Perry jokes, and maybe a significant percentage of all jokes. Maybe these theories are widespread because they're true—after all, men and women are not exactly the same; dissimilarities do exist. Or else we're drawn to them because they quietly justify lingering inequities.




The one variety of male-female friendship whose authenticity nobody questions, and which gets abundant screen time, does not rattle the gender-war thesis; I mean relationships between gay men and straight women. In reality, gay-straight friends come in all varieties (the equivalents of Brandon and Sue, Sean and Jody, Joel and Ruth). But in the popular imagination, the gay-male half of these relationships almost invariably takes on a feminine persona—he likes to shop and to gossip, like Stanford Blatch in Sex and the City. This isn't a friendship between a man and a woman, but a friendship between two people who both like guys. The gay man is just one of the girls.

When it comes to straight cross-sex friendships, such rationalizations are impossible. Here's a "regular" guy and a "regular" girl. Somehow they've overcome their natural differences and managed to build a platonic relationship.

In practice, moreover, cross-sex friendships challenge the very concept of what it means to be an ordinary guy. Academic research confirms the trope that when women get together, they spend their time communicating thoughts and feelings. Men are more likely to discuss neutral subjects such as sports, or engage in some activity. Summarizing the difference, the psychologist Paul H. Wright has said that women's friendships are "face-to-face" while men's friendships are "side-by-side." But when men and women start hanging around each other platonically, they meet somewhere in the middle in terms of emotional exchange. Research shows that cross-sex friendships are more emotive than male-male relationships and less emotive than female-female ones. In my own survey of nearly 600 Slate readers, I heard from men who said that what they like about their cross-sex friendships is the ability to share without fear of judgment, and from women who said they valued the opportunity to watch sports, for example, without having to pick apart their feelings.

It's possible that those who choose to enter into cross-sex friendships are less gendered to begin with—so it's not that the relationship encourages less stereotypical, less differentiated behavior, but is a result of it. Call it the Louisa May Alcott take—in the 1868-69 novel Little Women, Jo and Laurie have a platonic friendship, of sorts (Laurie proposes marriage but Jo rejects him). It's clear that they get along in large part because Jo isn't feminine—she's outspoken and rowdy—and because Laurie, in turn, isn't masculine: He's perceived as unmanly by his grandfather, not tough enough for the business world.




I know that, in my cross-sex friendships, the traits that supposedly make men and women so separate (excluding physical differences) are hardly in evidence. My friend Jeff preferred art class to gym class (he hyperventilated when he had to run a quarter mile our freshman year), wrote poetry about the girls he liked, and would tidy his room, including the closets, before they came over. He cries when he watches E.T.—or at least he did when we saw the 2002 rerelease in theaters. As for me: I don't watch sports; I have poor hand-eye coordination; I don't play video games. But I don't like to shop, and I confess I'm not entirely sure how to apply eyeliner. E.T. has never made me cry.

Did Jeff and I become friends because we don't fit gender typecasts to an unusual degree (the Alcott take), or did our friendship make us more androgynous? The answer probably comprises a bit of the former and a bit of the latter, but either way, our friendship led me, at least, to dismiss the whole Mars-Venus thing. As a greater percentage of men and women experience cross-sex friendships, it stands to reason that more people will come around to this point of view and that the more extreme versions of the gender-divide argument will fall out of favor.