Consider this a warning: the theory I’m about to describe is likely to boil untold liters of blood and prompt mountains of angry fists to clench in revolt. It’s the best—the kindest—of you out there likely to get the most upset, too. I’d like to think of myself as being in that category, at least, and these are the types of visceral, illogical reactions I admittedly experienced in my initial reading of this theory. But that’s just the non-scientist in me flaring up, which, on occasion, it embarrassingly does. Otherwise, I must say upfront, the theory makes a considerable deal of sense to me.

The work in question dates back to 1995-1996 and involves a four-paper exchange published in Ethology and Sociobiology. It is a dialogue between two influential evolutionary psychologists—Gordon Gallup of SUNY-Albany, whose work on human sexuality I’ve covered before, and British psychologist John Archer of the University of Central Lancashire. Their primary debate is about whether or not people’s aversion to homosexuality (colloquially called "homophobia," although both authors acknowledge that this is a misnomer because it is more a negative attitude towards this demographic than it is fear) is a product of natural selection or, alternatively, a culturally constructed, transmitted bias. That this discussion ended in 1996, and not a single study to my knowledge has sought to disentangle the various knots in both scientists’ positions, is revealing in its own right, and probably reflective of shifts in the social zeitgeist since then.

As Archer notes, most evolutionary research on homosexuality involves trying to locate its fringe gene-enhancing benefits. This homosexuality-is-adaptive-too approach complements a growing tolerance for gay individuals, such as, happily, myself. Gallup comes at things from a very different angle, instead asking why there is such disdain for gay people to begin with and—although cultures may vary in their relative degree of tolerance or practice of homosexual behaviors—why no cultures actually endorse exclusive, lifelong same-sex relationships.

The Gallup-Archer debate hinges on a multi-study empirical report by Gallup. In it, he aims to test his hypothesis that negative attitudes toward homosexuals is a function of parents’ implicit concerns that their children’s sexual orientation is malleable. Formulated originally with Susan Suarez in 1983, Gallup’s idea involves the following central prediction:

So-called homophobic reactions should be proportional to the extent to which the homosexual [is] in a position that might provide extended contact with children and/or would allow the person to influence a child’s emerging sexuality.

Remember, adaptive behavior is behavior that simply favors genetic replication. So just as being cuckolded results in maladaptive, unprofitable parental investment in someone else’s biological offspring, gay offspring—even your own biological child—are less likely to reproduce, and are likewise genetically costly. There are caveats. Just as a stepchild can contribute to one’s genetic success in indirect, non-reproductive ways—for example, by helping to raise your younger biological offspring, their half-siblings—gay offspring can do the same. But Gallup’s is an all-else-being-equal argument, and it makes sense in strictly biological terms. "In its simplest form," he clarifies, "parents who showed a concern for their child’s sexual orientation may have left more descendants than those who were indifferent."

Gallup’s position rests on a set of assumptions about the development of sexual orientation, assumptions that are in fact challenged by Archer. We’ll get to Archer’s criticisms eventually, as well as Gallup’s responses to them. But first, let’s have a look at how Gallup went about testing his hypothesis that homophobia stems from unconscious, gene-driven, parental concerns.

In his first of four studies, Gallup administered a survey to 167 self-identified straight undergraduate students—males and females—a survey designed to gauge the student’s "degree of discomfort" in interacting with homosexuals who held different jobs. Importantly, these occupations varied along one dimension: the extent to which the job entailed interaction with children. Included were nine sample occupations—three that afforded a high degree of contact with kids (teacher, school bus driver, medical doctor) and six that provided moderate to low contact (lawyer, construction worker, bank teller, pilot, mechanic, sales clerk). As predicted, the degree of discomfort was significantly correlated with the likelihood that persons in these categories would come into contact with children.

Intriguingly, hypothetical gay medical doctors elicited the most discomfort among the participants, an unexpected finding that Gallup sought to better understand in his second study. "There are at least two ways to interpret the greater discomfort expressed by respondents concerning homosexual doctors," he writes:

One possibility is that medical doctors have privileged access to children’s genitals in the context of conducting routine medical examinations, and therefore might be perceived as posing a more serious threat to a child’s developing sexuality. An interesting alternative interpretation concerns the prospect of contracting [HIV] from a homosexual doctor through nonsexual modes of transmission (e.g., blood, hypodermic needles).

In the second study, all of the characters were doctors of various kinds, physicians varying in the extent to which they would have intimate contact with children (pediatrician, child psychiatrist, general practitioner, cardiologist, brain surgeon, gerontologist). When left uninformed about the doctor’s sexual orientation, participants expressed the most discomfort about the prospect of interacting with those who had "invasive" techniques, such as the brain surgeon. But the picture changed dramatically when they were told the doctor was gay. Contrary to the HIV-exposure hypothesis, which should have produced little to no differences in attitudes toward the different gay doctors, it was the opportunity for intimate contact with children that correlated with discomfort. The participants were significantly less comfortable about the idea of interacting with gay pediatricians and general physicians than they were for the other types of gay doctors. In fact, gay brain surgeons, associated readily with infectious material, elicited the least aversion.

Gallup’s third study was even more revealing. Imagine, undergraduate participants were told, that you had a son or a daughter, either an 8-year-old or a 21-year-old, who was invited to spend the night at a friend’s house. On a scale of 1 ("not at all upset") to 4 ("very upset"), how upset you would be, as a parent of this hypothetical child, to learn that the friend’s mother or father was gay? The participants expressed most concern when their imaginary younger child was exposed to same-sex homosexual parents (young sons being around the friend’s gay father; young daughters being around the friend’s gay mother). This was especially pronounced (mean concern = 3.3) for male participants thinking about their imaginary eight-year-old son (compared to 2.3 at the thought of him being around a lesbian). These very same male participants didn’t seem to mind the prospect of their 21-year-old son being exposed to their friend’s lesbian mother (1.6), or even for this older imaginary son spending the night around their friend’s gay dad (2.3). So, the participants’ homophobia didn’t seem to be moralistically generalized to the "gay lifestyle" but instead it emerged specifically in terms of their folk beliefs about children’s sexual impressionability.

Gallup’s final study replicated his basic findings with a broader sample. Nearly two hundred people from the Albany area, varying along a wide range of demographics (age, sex, religiosity, education, number of gay friends) were polled on a "Homosexual Reproductive Threat Scale." Participants responded to statements such as, "I would feel uncomfortable if I learned that my daughter’s teacher was a lesbian," "I would feel uncomfortable if I learned that my neighbor was a homosexual," and so on. As you might expect, variables such as sex (males being more negative) and religiosity predicted homophobia. But parental status was independently correlated with negative attitudes to gays and lesbians, too; and this effect was especially salient for the males in the survey. Fathers with young children were the most homophobic.

A year after Gallup published his theory of homophobia, Archer critiqued it in the same journal. "I shall argue," he writes, "that there is perhaps too great a willingness to assume that the sorts of human behavior with which we are familiar today can necessarily be viewed in adaptive terms." Archer rightly notes, in fact, that the best predictor of adult sexual orientation is gender nonconforming behavior in early childhood. So Gallup’s central position that homosexuality occurs via "seduction" of (especially male) children is flawed. Rather, says Archer, "the link between pedophiles and male homosexuals is one that has been encouraged by media depictions of all those with nonheterosexual orientations as deviant."

Not so fast, Gallup reacts to this media conspiracy claim:

Although the incidence of heterosexual pedophiles exceeds that of homosexual pedophiles by a factor of about two to one, individuals in the population at large with a heterosexual orientation outnumber those with a homosexual orientation by about 20 to 1. Thus, although there are fewer homosexual than heterosexual pedophiles, the proportion of homosexual pedophiles is considerably higher than that of heterosexual pedophiles. Homosexual pedophiles also tend to be highly promiscuous. [In 1987], the mean number of victims of heterosexual pedophiles was 19.8, whereas among homosexual pedophiles the average number of victims was 150.2. Because they have more victims, homosexual pedophiles have a correspondingly greater likelihood of being apprehended, and this might account for their disproportionate representation among those arrested for sex crimes.

Furthemore, Gallup never claims that being seduced by a gay pedophile is the only path to homosexuality, nor that—obviously—"turning gay" is an inevitable outcome of being molested by an adult of the same sex. Instead, he argues, in the ancestral past, such developmental experiences would have led to statistically more homosexuality outcomes than would the absence of such encounters, and thus there was a selection bias for homophobia, apparently exacerbated by becoming a parent.

Recent evidence offers some support for Gallup’s model: men—but not women—who were sexually abused as children by same-sex adults are more likely than non-abused males to have homosexual relationships as grownups. Most researchers believe that there is something like a "sexual imprinting" process that occurs in early development, which may help to explain this, as well as fetishism and paraphilias. Note also that some of the most virulent homophobia today can be found on the playgrounds, which is consistent with the sexual imprinting model. Children and teen’s stubborn reluctance towards tolerating gays and lesbians may itself be an adaptive proscription orienting them away from same-sex experimentation. Gallup points to data showing that boys whose first masturbation experiences are around other boys are more likely to be homosexual as adults than are those who are alone.

Archer favors an alternative evolutionary theory of xenophobia (hatred of outgroup members) to account for Gallup’s findings. Gays, he argues, have been homogenized into stereotypical pedophiles because of media biases, just as racist British people refer to anyone of certain Asian origin—whether from Pakistan, Bangladesh, Sri Lanka, or Pakistan—as "Pakis." Xenophobia would have been an adaptive strategy in the ancestral past, says Archer, given the ever-present threat of social dissidence within groups and also the invasion of other groups.

But, replies Gallup, this still doesn’t explain the data in hand. "How can xenophobia," he counters, "account for the fact that college students who have yet to become parents feel more uncomfortable about the prospect of being in the presence of a homosexual teacher than a homosexual construction worker or airline pilot? Similarly, how would an appeal to xenophobia explain the fact that students report feeling more uncomfortable about the prospect of being in the presence of a homosexual pediatrician or general practitioner than a homosexual brain surgeon?"

And this, as I mentioned, is pretty much where the debate ends. I’ve revived this fifteen-year-old discussion in the hopes that it might spark new research. Gallup’s work is intriguing, his theory sound. Yet his studies are imperfect, the data remain un-replicated, public attitudes have changed (dramatically, in the US) and other cultures may differ in response to homophobia manipulations. One thing that is important to keep in mind, however, is that societal changes in attitudes toward homosexuals may not mirror people’s implicit biases. Today’s answers may very much sound like the voice of gay-friendly 2011 but, as any social psychologist knows, you can’t always trust what people tell you as reflecting their private attitudes. (They may not even be aware of these themselves.) So researchers today would have to be very clever in probing for what have rapidly become socially inappropriate feelings.

Sometimes, science can be exceedingly rude—unpalatable, even. The rare batch of data, especially from the psychological sciences, can abruptly expose a society’s hypocrisies and capital delusions, all the ugly little seams in a culturally valued fable. I have always had a special affection for those scientists like Gallup who, in investigating highly charged subject matter, operate without curtseying to the court of public opinion. And, before anyone does so, what an absurd, spineless suggestion for science to refrain from engaging in any intellectual inquiry, from exploring theoretical possibilities, because we fear what we may learn about ourselves. It’s the devils we don’t know that we have the most to fear. That Gallup’s ideas could be championed by antisocial conservatives to promote further intolerance against gays is inevitable, perhaps; but if it’s any consolation, it should also have them doing a bit of navel-gazing, seeing that their hatred is just an artifact of their godlessly evolved minds.

About The Author: Want more Bering in Mind? Follow Jesse on Twitter @JesseBering, visit, or friend Jesse on Facebook. Jesse is the author of newly released book, The Belief Instinct: The Psychology of Souls, Destiny and the Meaning of Life (W. W. Norton).