Most of us don't want to judge others by their appearance. Yet if we're honest, don't we all, at least occasionally, feel an unwelcome twinge when we find that the woman seated next to us on a flight is obese, or the teller who greets us at the bank bears a port-wine stain on his face?
A relatively new, yet growing body of research suggests that such gut-level responses may be a type of protective prejudice, a set of innate cognitive and behavioral responses that evolved to help us detect and avoid potential disease. Consider it the brain's way of engaging in a form of preventive medicine, says Mark Schaller, a professor of psychology at the University of British Columbia. "We're on the lookout for signals indicating that those around us deviate from what's 'normal' in some way," he explains. When we detect a possible sign of illness in others—a runny nose, say, or an unusual lesion on the skin—we automatically give them a wide berth, and sometimes worse.
It's an unconscious strategy for avoiding a wide range of potential infections, since we have no way of detecting germs themselves. But since the consequences of missing a sign of disease are serious, possibly even fatal, and the array of symptoms wide, our behavioral immune system (as Schaller has dubbed this suite of responses) tends towards over-sensitivity—which is why we might be more averse to practically anyone who strikes us as anomalous. That includes a man in a wheelchair who poses no disease threat at all. Recent scholarship bears this out; for example, research published in Evolution and Human Behavior revealed that disease-avoidant psychological processes play a driving role in prejudices against people who are obese or disabled.
"Protective prejudice" may also fuel an instinctive distrust of strangers. It makes sense—in terms of strict self-preservation—to be wary around those whose behavior and dress suggest they're outsiders. They may bear pathogens against which we, and others in our community, carry no immunity. They may practice traditions of hygiene and food preparation that aren't as effective as our own at eliminating germs and parasites common in our region.
Even if we try to hide our reactions, our instinctive concerns about those who look unusual are biases we impart to others through everyday interactions. Left unchecked, such discomfort can grow powerful enough to predispose whole societies towards xenophobia, and along with it, violence against those seen as outsiders. Yet by understanding the underpinnings of protective prejudice, we can learn to combat it rather than overextend it, on both a personal and a global scale.
Protective Prejudice in Action
All things considered, our immune system does a great job of keeping us safe from disease. When microbes or other foreign invaders are detected inside our body, swarms of specialized cells mobilize to destroy the enemy. But there's a built-in limitation to this defense scheme: By the time the immune system goes into action, the invaders have already breached the walls, and dislodging them takes energy and resources (we all know the exhaustion that comes with fighting off a cold or flu). "If we can use our senses to detect infection risk—and then do something that prevents us from coming into contact with such threats—that holds tremendous advantages," Schaller says.
It's not just humans who take pains to avoid becoming infected in the first place; a wide range of animals engage in behavioral strategies to stave off disease. Scientists have discovered that some ants, for example, can detect fungal spores among their brethren and groom each other to minimize infection. Certain rodents sniff each other as a way of checking for parasites, and chimpanzees have been observed avoiding diseased individuals in their social groups. Jane Goodall famously documented how Mr. McGregor, a once popular chimp, was shunned after he contracted polio, which left him without the use of his legs, forcing him to move by dragging himself with his arms.
A 2010 study led by social psychologist Chad R. Mortensen, of Metropolitan State University of Denver, found that people who were shown images of sick people were quicker to make "avoidant" arm movements in a computer game, as if primed to push away a threat. Another study by the same team revealed that when people were shown discomforting information about infectious diseases, they rated themselves as less sociable—in effect, giving themselves permission to avoid others and their potential germs.
Concern about parasitic infection correlates with anti-immigrant attitudes; in one study, people who viewed images relating to illness were more likely to express negative attitudes about foreigners. Research further suggests that such biases are heightened at times when people are more vulnerable to infection. For example, a study led by Michigan State University researcher Carlos Navarrete found that women tend to be more xenophobic in the first trimester of pregnancy—a time when the immune system is suppressed so that it does not attack the fetus. Conversely, psychologists have also found that when people feel protected from disease—say, if they've just had a flu shot—xenophobic attitudes diminish.
The Connection Between Disease and Violence
Beyond affecting our reactions to others, the behavioral immune system may influence how we act on the population level, shaping cultures around the world. For example, a study by Schaller in the Journal of Personality and Social Psychology demonstrated that in areas where disease is prevalent, people tend to be less extroverted.
Other research suggests that in regions with a high prevalence of infectious disease, such as Colombia and Somalia, cultures tend to favor collectivism over individualism, conservatism over liberalism, autocracy over democracy. Even within this country, states that have higher rates of disease (such as Louisiana, South Carolina, and Alabama) also tend to have stronger indicators of collectivism, like religiosity and an emphasis on family ties, according to University of New Mexico biology professor Randy Thornhill. "It's important, under high threat of disease, to build social alliances with locals," he says, and to favor our own kin over outsiders. "You need a social network of reliable people in your group who will help you through the onslaught of disease. That's the only health insurance that human evolutionary ancestors had."
In addition, Thornhill says, high parasite stress tends to promote philopatry, the tendency to remain in one place. "If you stay where you were born and raised, you'll be relatively immune to the local parasites," whereas striking out for new ground carries the risk of exposure to novel germs and diseases.
Research by Thornhill and others supports the idea that in places where disease rates are high—Afghanistan, for example—the consequent xenophobia, in-group favoritism, and philopatry tilt local customs and values toward harm ful and exploitative behavior. A collectivist outlook, he argues, may increase the likelihood of crime and violence against others since people feel less compunction about mistreating those to whom they're not connected—and because people who are insulted or disrespected are more likely to respond violently if they feel a need to defend the honor of their group, be it family, clan, or gang.
In 2011, Thornhill examined rates of violence and found that the prevalence of disease correlated strongly with homicide rates across the United States. In fact, disease threat turned out to be the best predictor of the variation in homicide levels—more so, for example, than income inequality or personal hardship. Another analysis found that disease prevalence also predicted homicide rates worldwide. Furthermore, a 2013 study by Loyola University psychologist Ilan Shrira revealed that across the United States, infection rates are related to rates of homicide committed against strangers—but not family members or other known individuals—which lends support to the notion that it's a fear of outsiders that links disease and crime rates.
Thornhill's research also suggests that the presence of disease is a strong predictor of civil war, tribal warfare, and other large-scale armed conflicts within nation states. "If you get high levels of xenophobia, then one group feels so negatively about another group that they want to kill them," he says. "So you get more large-scale violence like clan wars in regions with high parasite stress."
Beating the System
If prejudice and xenophobia are, at least some of the time, the results of an innate system that helps us to avoid disease, that's not to say that we're innate bigots. The definition of who is and isn't in our group is something we learn. "We don't know at the beginning which folks are from different groups," says Steven L. Neuberg, professor of psychology at Arizona State University. "There's nothing in our head that inherently says, for example, 'People who don't possess our skin tone are bad.'"
It is possible to control even real disease avoidance—such as steering clear of someone with a rash or a hacking cough, Neuberg notes, citing how nurses or physicians may initially be repelled by the condition of patients they encounter during their first days of hospital training but quickly learn to override their automatic responses.
Bigotry and xenophobia are behaviors that can be altered. Despite the high sensitivity of the behavioral immune system, it wouldn't work if it weren't capable of shifting in response to the changes around us. "We can learn that cues are no longer relevant," says Neuberg. "One of the things that makes us uniquely human is this ability to learn and to respond flexibly to different situations and people."
Research suggesting that prejudice is a flexible trait abounds—and simply being aware that it's not fixed can significantly reduce discriminatory behavior. Accepting that we all hold negative associations and becoming aware of the ones we automatically make are also critical steps in the process of counteracting our biases. So, too, is encouraging people to talk about their negative preconceptions.
On a population level, tamping down on our automatic aversions could also be accomplished by lowering disease risk. Researchers argue that this could be a relatively straightforward approach to lowering rates of homicide, warfare, and other forms of violence worldwide. "Cleaning up infectious disease is a big task," Thornhill admits, "but putting in a sewage treatment plant to provide clean water is cheap compared to the cost of a civil war or a long-term clan war."
Cost isn't the only challenge to enabling change on a large scale, though. There's also a need for patience and planning. While individuals can overcome their prejudiced responses, Thornhill expects that it would "take a generation" for population-wide effects to be seen. Kids who grow up in areas with a high prevalence of pathogens might become less xenophobic if illness rates plummet—but it's their kids, raised from the beginning in an environment less fearful of disease, who should show a game-changing shift in prejudicial attitudes.
Theoretically, the concept could be tested here in the United States by improving health care in states that have high homicide rates. Practically, that might be difficult, given the contentious debate regarding health-care reform in this country. But Thornhill points out that, in a way, such a test has already been conducted: Health-care improvements that took place in the West during the 1920s through the '40s—such as vaccination programs, chlorination of water, and widespread availability of antibiotics—were followed by increased liberalism, decreased collectivism, and widespread acceptance of cultural diversity in the 1960s and '70s.
Time will tell whether eliminating infectious disease discourages violence and warfare. If it doesn't, preventing life-threatening illness is a valuable outcome in itself. Meanwhile, Dan Gottlieb has this advice for those who find themselves on the receiving end of protective prejudice: "People are hardwired to discriminate, but there's a responsibility to teach a different way. It's been thrust upon you." When he finds himself in the presence of someone made uncomfortable by his disability, Gottlieb takes it upon himself to ease the anxiety and engage in an educative moment. "I say, 'It's OK to talk to me.' After that, I can see people's body language change; their shoulders relax. It's a relief."
Rick Chillot is a writer and an editor at Quirk Books. He lives in Pennsylvania.
A Hair-Trigger Reaction
The behavioral immune system not only triggers behaviors that help us avoid infection, it appears to activate the cellular immune system as well—just in case our actions don't succeed in helping us dodge an infectious bullet. University of British Columbia professor of psychology Mark Schaller and his colleagues showed study subjects a series of photos depicting either symptoms of infectious disease (sneezes, skin lesions) or another kind of threat (guns). They also took blood samples before and after to test for immune system activity. The research team found that study participants who'd viewed slide shows of medical symptoms experienced a spike in immune system activity, while those who'd viewed the images of firearms showed barely any difference.
Charlie Gunderson | 17, Dallas, Texas
I'm a senior in high school, and I'm just three-foot-eleven. I was born with achondroplasia, a form of dwarfism.
I've had it pretty easy—people are laid back here in Texas. The most common reaction that others have to me in public is staring. I get it; it's human nature to stare at those who are different, so I don't get upset. When it happens, I just focus on doing my own thing. The only comments I ever get are from little kids, and I'm not going to get mad about that, because they don't know better. Sometimes people get confused about how old I am. Recently a woman seating me at a restaurant asked if I wanted a kid's menu. Later, my server offered me a margarita and a shot of tequila.
As a little person, it can be a challenge to figure out whom to surround yourself with. I'm picky about friendships because I need to be sure people are interested in me for the right reasons. Some people just think it would be cool to be seen with a dwarf.
I don't talk about "dwarf problems" with most people—I just figure them out for myself, or I talk about them with dwarf friends I've met through The Painted Turtle, a summer camp that has a session each year for kids with skeletal dysplasia and other medical conditions. I went seven summers in a row, and I'd like to work there on staff someday. The little people I met there see me for me and not my dwarfism. You forget that you're "different." It's awesome to be able to see eye to eye with someone—literally.
Michael Carraway | 19, Ellicott City, Maryland
I'm a college student and an entertainer—I make YouTube videos under the name Mike Creezy. I started making them because I act, dance, sing, and produce music—but eventually I realized that by telling stories I could also help people. One way I've done that is by making videos about my vitiligo.
Vitiligo is a condition that causes the skin to depigment. I have white patches on my face, elbows, feet, and several other places. The first spot appeared on my knee when I was about 10. When I was 16, my doctor tried to treat it, but nothing worked.
In public, people often look at me like I'm a freak—as if I'm not even human. In the mall once, someone said, "What is on your face? Get that checked out!" Some people think I'm wearing makeup.
People judge me before they bother to get to know who I am, but I never say anything back in anger. If I did, then they wouldn't have the chance to understand. My approach is: Let me inform you so that you won't be a jerk when you meet the next person like me. I try to explain my condition.
In a way, having vitiligo has been a blessing. It has allowed me to have compassion for others, to open my eyes to other people's hardships, to develop a strong set of values. I believe that I was put here to help and inspire other people. Telling your story can change another person's life.
Sarah Bramblette | 36, Portsmouth, Ohio
I weigh approximately 400 pounds. I've been obese all of my life. In my twenties I was diagnosed with lipedema and lymphedema, congenital conditions that cause an abnormal accumulation of subcutaneous tissue and fluid in my limbs.
Growing up I was told, "You have such a pretty face, it's a shame." Still, I vowed not to let my weight stop me. I had many friends and was a good student. I have great self-esteem—perhaps better than many of my non-obese friends.
I've experienced worse treatment as an adult. Once a woman in an electric cart said, "Check out them cankles!" The funny thing is that even with my cankles I was on my way home from the gym—and without a cart. I've also experienced bias in accessing health care (my conditions went undiagnosed for years because doctors always assumed I was fat because I was eating too much) and in the workplace. Obese people are often seen as lazy; on the job, I have to give 110 percent just so people will think I'm giving 90 percent.
While people's assumptions are hurtful, I try to find a positive perspective. My experiences inspired me to pursue a master's in health law, so I can work in health care administration. I also blog about my experiences. Others' judgments have been a catalyst for a life of advocacy.
Dave McGill | 44, Greenlawn, New York
In winter 1996, I was driving home at midnight when I noticed a woman standing in the road next to her car. It was snowing and cars were skidding around her. I said, "If someone doesn't help her, she'll get killed." I have no memory of being hit while I assisted her. When I came to in the hospital, I looked down and saw nothing below my knee on the left side.
When I wear shorts, it's obvious I don't have two legs. Kids gape. I never have any issue with it—at least kids are honest. Adults stare and then look away. I understand that impulse as well—but I think, "Just admit that you were leering at me." It's not entirely fair of me to respond that way. Most adults have never seen a prosthesis before; why should they behave in a more sophisticated manner than kids?
People relate to you differently if you're missing a limb. But I've had interesting conversations with people who were brave enough to say, "Do you mind if I ask...?" I don't.
Before the accident, I was your typical 26-year-old, putting a lot of what was important to me on the back burner. The accident allowed me to reframe what was important. I ended up cofounding a prosthetic facility in 2001. Now I have three kids. I can't imagine having a more fulfilling life with two legs.