Just Babies (16 page)

Disgust may be morally neutral when elicited by a dead rat or a puddle of vomit, but disgust at our fellow human beings is more troubling. Now, disgust is not identical to repulsion or hatred. You can hate someone who doesn’t disgust you at all in a visceral sense—though there is often the temptation to use the rhetoric of disgust toward those
we despise: “He makes me sick!” And you can feel disgust without hatred, repulsion, or any sort of negative feeling at all. Changing your child’s diaper or cleaning up her vomit might be revolting, but it doesn’t make you hate your child. Still, disgust ups the odds. To be grossed out by someone is, other things being equal, to be repelled by him.

Disgust is the opposite of empathy. Just as empathy leads to compassion in many (but not all) circumstances, disgust usually (but not always) leads to repulsion. Empathy triggers an appreciation of another’s personhood; disgust leads you to construe the other as diminished and revolting, lacking humanity.

Experimental research shows that feelings of disgust make us judge others more harshly. In the first experiment along these lines, the psychologists
Thalia Wheatley and Jonathan Haidt hypnotized participants to feel a flash of disgust whenever they saw an arbitrary word. When the participants later read stories of a mild moral transgression, those who saw the word rated the behavior as more immoral than those who didn’t.
In other experiments, participants were asked to make judgments at a messy, disgusting desk; or in a room that had been blasted with a fart spray; or after being shown a scene from the movie
Trainspotting
in which a character puts his hand into a feces-filled toilet; or after being asked to write about a disgusting experience. All of these situations made the participants more morally disapproving about the acts of other people.
Even eating a bitter food, which evokes a sensation akin to physical disgust, makes people harsher toward moral transgressions. And
consistent with these experimental findings,
individuals with high disgust sensitivity have harsher attitudes toward certain other people, such as immigrants and foreigners.

The consensus from the world and from the lab is clear: disgust makes us meaner.

S
EXUAL
practices are part of Rozin’s disgust scale. Respondents are asked to rate how disgusting it is for an adult woman to have sex with her father or for a thirty-year-old man to seek sexual relationships with eighty-year-old women. Many people do see such acts as disgusting. And they see them as immoral as well.

Our moral response to certain sexual activities is really puzzling from an evolutionary point of view. Most of the moral judgments I have been discussing throughout this book can be understood as evolved adaptations. The warmth we feel toward those who are kind and honest and the outrage we feel toward cheaters and free riders can be seen as adaptive solutions to the challenges of individuals living with one another in a small society. Our reactions to unfairness emerge from our evolved obsession with status; our reactions to assault and murder follow from the importance of surviving and having one’s kin survive. We think it is worse to intentionally kill someone than to knowingly allow the person to die (even when rescuing them would be trivially easy), because no society can survive if individuals could kill one another at will, but it’s less critical that we be obliged to save one another.

Other aspects of our moral thought are not themselves
adaptations, but they are natural extensions of adaptations. Our brains did not evolve to disapprove of modern crimes like arson and drunk driving, but these behaviors are seen as morally wrong because they fall into the general categories of intentional and negligent harm. I doubt that the logic of gift giving is encoded in our genes; rather, our intuitions about what’s appropriate to give, and our feelings of gratitude or disappointment, can be explained (at least in part) in terms of evolved concerns about status, respect, and reciprocity.

But sexual morality is different. Yes, it’s easy enough to see how any creature that reproduces through sex would evolve a desire to engage in sexual intercourse along with a desire to avoid certain sex acts that either don’t lead to reproduction (such as sex with nonhuman animals) or don’t lead to the right sort of reproduction (such as sex with parents, siblings, or one’s adult sons or daughters).
The mystery for moral psychologists isn’t why we would engage in certain types of sex while avoiding other types; it’s why we should be so concerned with the sex that other people are having.

For example, sexual intercourse between two people of the same sex is forbidden in much of the world and is sometimes punishable by death. In the United States, it was only in 2003 that the Supreme Court, in
Lawrence v. Texas
, deemed sodomy laws unconstitutional; up until then, thirteen states had laws against same-sex sexual relationships. Many prominent social and religious figures continue to decry homosexual relationships as immoral, and homosexuals are victims of bullying, harassment, and even murder.
In a recent poll (May 2012), 42 percent of adults said that “gay or lesbian relations” are morally wrong.

It used to be worse, of course. Take Thomas Jefferson, whose wise words on our moral natures are quoted at the start of this book. In 1777,
Jefferson proposed the following law for Virginia: “Whosoever shall be guilty of Rape, Polygamy, or Sodomy with man or woman shall be punished, if a man, by castration, if a woman, by cutting thro’ the cartilage of her nose a hole of one half inch diameter at the least.” As brutal as this now seems, Jefferson was merciful by the standards of the era. His proposal was rejected because it wasn’t harsh enough; the legislature wanted, and ended up with, the death penalty for these acts.

What’s particularly noteworthy here is Jefferson’s conflation of rape—always a crime for obvious reasons—with consensual sexual acts such as sodomy. Our disapproval of such acts is perverse from an evolutionary perspective. After all, there is no genetic downside to homosexual activity. There’s no risk of malformed offspring, and there might be an overall benefit in establishing and strengthening social bonds through sexual contact.

Now,
exclusive
homosexuality does have negative reproductive consequences for the individual. But, still, given the fierce nature of mate competition, it makes no sense for men to be bothered by other males who are exclusively homosexual. A good Darwinian would predict the opposite. Men who have sex with one another (or who devote themselves to any other harmless nonreproductive activity instead of trying to impregnate women) are pulling
themselves out of the mating market, giving every other male a relative advantage. Male homosexuals should inspire gratitude, not disapproval. Women should be the only ones bothered by male homosexuals, just as men should be the only ones bothered by female homosexuals.

So much the worse for evolutionary explanations, then. Perhaps our moral disapproval has cultural roots. But finding a cultural function of this restriction is no easier. It’s sometimes said that societies condemn homosexuality because encouraging reproductive sex helps to keep the population large. But women, not men, are the limiting factor in the production of children, so this would only explain disapproval of female homosexuality. Indeed, given the emphasis through human history on controlling the sex lives of women, one would have predicted that lesbians would be the sole focus of moral censure, not gay men.

Incest is another sexual behavior that is condemned in just about every culture. People often have explicit explanations for this restriction. When the anthropologist Margaret Mead questioned a member of an Arapesh tribe about what he would think of a person who married his sister, he explained that marrying outside the family was necessary to build alliances:
“What, you would like to marry your sister? What is the matter with you anyway? Don’t you want a brother-in-law? Don’t you realize that if you marry another man’s sister and another man marries your sister, you will have at least two brothers-in-law, while if you marry your own sister you will have none? With whom will you hunt, with whom will you garden, whom will you visit?” In our
society, one might raise concerns about consent, psychological harm, or the possibility of deformed children.

But while there might be perfectly sensible reasons for opposing incest, our instinctive repugnance at the thought of this act comes from a deeper place.
As the psychologist Steven Pinker points out, parents of teenage children have all sorts of concerns, but they don’t usually worry that their kids will sneak off to have intercourse with one another. Teenagers do not refrain from sibling incest because they’re concerned that they will have a shortage of in-laws to hunt and garden with or because they are worried about deformed children. Sibling incest is rare simply because most siblings don’t want to have sex with one another; the very idea is disgusting.

There is an evolutionary logic to this disgust response. It’s clearly a bad idea to have children with your close relatives, because of the likelihood that the child will inherit two copies of an allele that would be harmless on its own but deleterious in a pair. When people do have sex with kin, it is often by mistake, as when siblings, separated early in life, meet and get married and only learn later that they are blood relatives.
Co-residence during childhood is one of the cues that seem to trigger the mental system that steers us away from incest. People respond to this cue even when they are not actually related by blood, which explains why
a stepfather who enters the family when the daughter is past a certain age, as opposed to being around when she was a baby, is more likely to later be sexually attracted to her. He is also more likely to kill her. (I should add the obvious
here, which is that most stepparents, even those who enter the family late, never assault their children, sexually or otherwise. Most of us are moral beings, and there is a large chasm between desire and action.)

But none of this explains why incest committed by
other people
bothers us so.
Consider a well-known hypothetical, carefully constructed by Jonathan Haidt to avoid the consequences that are usually connected to incest, such as concerns about coercion or deformed children:

Julie and Mark are brother and sister. They are traveling together in France on summer vacation from college. One night they are staying alone in a cabin near the beach. They decide that it would be interesting and fun if they tried making love. At the very least, it would be a new experience for each of them. Julie was already taking birth control pills, but Mark uses a condom too, just to be safe. They both enjoy making love, but they decide never to do it again. They keep that night as a special secret, which makes them feel even closer to each other. What do you think about that? Was it ok for them to make love?

Most people say that Julie and Mark did something wrong. Interestingly, when asked to articulate the basis for this judgment, most cannot, a phenomenon that Haidt describes as “moral dumbfounding.” It just feels wrong.

If you distrust these sorts of artificial examples, here’s a
real one. In 2010, a political science professor from Columbia University (who studies game theory, of all things) was charged with
“third-degree incest” for having consensual sex with his twenty-four-year-old adult daughter. The legal charges were accompanied by sensationalistic coverage in newspapers and blogs, and there were demands that he be fired from his position. Clearly, many people thought his actions were immoral.

Laws against incest, even those that apply to consenting adults, can certainly be defended on consequentialist grounds. Knowing that one’s young son or daughter will be an acceptable sexual partner in the future might distort the relationship between a parent and a child. More generally, sexual relationships might be incompatible with the special ties that hold between certain blood relatives, even as adults, so society might be better off if such relationships are not permitted. But these concerns were probably not the source of many people’s disapproval of the professor. Rather, his activity grossed them out—it was seen, in the words of the
New York Daily News
, as “a sick sexual relationship.” There might be good reasons to ban consensual incest, but we wouldn’t be so quick to come up with these reasons if we weren’t already disgusted by the idea in the first place.

I
DON
’
T
think it is a coincidence that the sex acts that we disapprove of are the very same ones that we think of as disgusting. Rather, disgust is part of the solution to the problem of sexual morality.

Disgust is our natural default toward certain sex acts, and, as we have seen, disgust triggers repulsion and rejection. The psychologist Nilanjana Dasgupta and her colleagues found that
viewing disgusting images led to more negative implicit attitudes toward homosexuality, while a study that I did with the psychologists Yoel Inbar and David Pizarro found that
exposing people to a bad smell—a fart spray—made them report less warmth toward gay men.

This predicts that an individual’s disgust sensitivity should be related to his or her attitudes about sexual behavior. To explore this idea, Yoel Inbar, David Pizarro, and I measured the disgust sensitivity of a broad sample of American adults (leaving out any questions about sexual disgust) and found that
greater sensitivity was associated with more conservative attitudes on a range of political issues—and the association was particularly strong for sex-related issues such as abortion and gay marriage. The effect held even when we factored out gender, age, and religious affiliation. In a second set of studies, adding Yale philosopher Joshua Knobe to our team, we tested students at the University of California, Irvine, and Cornell University. This population is highly socially liberal and, when explicitly asked, tends to be unbiased toward homosexuals. Still, the
students’ disgust sensitivity scores correlated with their implicit attitudes about homosexuals: the more disgust-sensitive they were, the more negative their attitudes.