Don't Look, Don't Touch, Don't Eat: The Science Behind Revulsion

by Valerie Curtis

  The disgust system is tuned to overreact; it’s better to miss one meal, or one mating opportunity, than run the risk of contracting a life-threatening disease.23 Hence, disgust responses are precautionary and disproportionate to actual current risk. There have been running battles in California about the reuse of wastewater, largely because of scaremongering about contamination—the insinuation that almost infinite dilutions of contaminants might be harmful in water that has “passed through several people.” Such arguments have derailed much-needed water purification schemes.24

  As the food industry knows to its economic cost, even the slightest suspicion that products may have been contaminated leads to mass shunning that can affect a far wider range of products and goes on for much longer than is warranted by any actual health risk. Meat is already a suspect product because of its ability to carry and support the multiplication of bacterial contaminants; hence, when mad cow disease came along (which had nothing to do with bacteria), beef became suspect and consumption dropped dramatically, at a huge cost to farmers in the UK.

  Indeed, disgust is probably the main reason that we throw out over a third of all of the food we produce. In a society where we are no longer hungry, the slightest sign of a mark on a fruit makes it suspect and hence unsalable in the supermarket, and the sniff test or the sell-by-date destines food for the wastebasket. I grew up in a society that made a virtue of thrifty cooking, so I’m shocked to find that some of my kids’ friends won’t eat anything that I make that contains leftovers. Babies, too, are deprived of good nutrition by overactive disgust. One reason for the decline of breast-feeding in the UK is that some mothers find the practice of feeding bodily fluids to an infant disgusting.25 Breast-feeding is a lifesaver in low-income countries. But mothers we talked to in Zambia told us that they preferred to wean early, partly because they found the smell of breast milk spilt on clothes disgusting and feared that it would repel their husbands. Disgust is a strong affect; its sticky labels are easy to apply to things and very hard to peel off.

  Doing the Dirty Jobs

  Individuals whose work or lifestyle involve, or bring to mind, infectious fluids tend to suffer from sticky labeling too. The best-known example is the sweeper, or Dalit (previously known as the “untouchable”), in India. Studying the problem of sanitation in Lucknow, I covered my head with a dupatta and went out before dawn to watch the sweepers. As it began to get light, women and men could be seen moving from house to house sweeping steaming offerings from small holes in the backs of houses into baskets that they carried on their heads to empty into the nearest drain. No one noticed or greeted these shadow people; it was as if they did not exist. In Ghana, I learned that the same job of emptying bucket toilets could not be done by Ghanaians, but instead was done by members of a neighboring Burkinabé tribe, the Dagari. “Would you let your daughter marry a Dagari?” I asked Akan respondents. “No way” was the usual answer.

  The toilets in my commuter train into London are tended by a range of non-Brits, taking a job that the natives don’t want, as their first brave step on their way up the international career ladder. Being honest here, I’m not sure that I’d be happy to see my daughter marry a train-toilet cleaner either, for reasons that surely include contamination.

  In France the word putain, which means “whore,” is said to originate from the idea that prostitutes stink (puer) because of the sexual fluids that they absorb.26 And females in general are suspect because they may be menstruating—which can spoil the sauce in Italy, stop bread rising in the north of England, and require monthly sequestration in Kenyan, Nepalese, and Native American cultures. The Old Testament forbids sex during menstruation, and a survey for a tampon manufacturer in the 1980s in the United States found that half of both women and men thought that one should not have sex during menstruation, presumably due to the double disgust of blood and sexual fluids.27 A national survey in the United States in 1993 reported that 89 percent of adolescent males found the idea of sex between two men disgusting28—disgust of sex and bodily fluids spreads and sticks—contaminating the very gay identity. The negative effects don’t stop there. Disgust’s hyper vigilance can be tripped by a range of conditions like epilepsy, mental illness, mental retardation, obesity, skin conditions such as psoriasis, cancer, and HIV, all hard, if not impossible, to catch via social contact.29 Though it may have been adaptive in our ancient past to flee strangers with signs that they might be carrying an infection, such responses are wrongly calibrated for a modern world where infection is much rarer. Individuals with disabilities or disfigurements automatically activate thoughts of disease in onlookers, even when the perceivers know perfectly well that these individuals do not have infectious conditions.30 People who are more concerned with disease are less likely to have friends with disabilities, to dislike obese individuals more, and to display implicit ageism.31 Human faces made up to look sick are found to be more disgusting than healthy counterparts.32 As a consequence those who are sick face a double burden—they suffer with the condition, and they suffer discrimination from those around them—or at least, they fear possible discrimination.

  Shame, as the flip side of disgust, leads people to sequester themselves, to avoid disgusting others. Teenagers try to hide the acne that causes shame and poor self-image, and women with obstetric fistula (vaginal damage that causes incontinence, which is common in places with poor obstetric care) sometimes remove themselves from society for fear of causing offense.33 Beyond the suffering of sickness, hospital patients often have to deal with the shame of public evacuation. One doctor recounted the problem from his own experience: “To lay in bed, and against all physical rules, and I may say psychological rules as well, and do what you normally do at the toilet was a humiliating experience of the helplessness patients feel when help with basic functions is needed. Why did I never question this part of caring when I worked as a doctor? For us, defecation was only an abstract category in the patient’s medical record.”34

  Terminally ill people often fear losing control over their physical functions and hence becoming dirty and “untouchable.”35 So the old, the frail, the sick, and the disabled, all those who have to hand their body care to others, have to live in shame, fearing the disgust that they may cause.

  Policy makers sometimes dismiss such fears as simply irrational, effectively asking people to “get over it.” But this is to make a major error about human nature. Rules about continence with bodily fluids are based on powerful ancient emotional drivers of behavior, as well as on the manners that are inculcated into everyone at an early age. Fear of shame is a serious and a seriously debilitating matter that can’t just be reasoned away.

  And while patients may fear the disgust response of the caregiver, the caregiver also has to deal with her or his own disgust response. Caregivers have to overcome revulsion for the bodily fluids of those they care for. Sickness can strain relationships, for example, when the partners of AIDS patients find themselves having to deal with the messy processes of disease.36 Despite their often heroic denials, it is clear that caregivers too suffer from stress and pay an emotional cost in overcoming disgust. To dismiss this as irrational is, again, unhelpful. Caregivers need the emotional labor of their work to be recognized, discussed, supported, and rewarded.37

  Beyond those who care for the sick, professions that involve encounters with disgust elicitors also involve emotional labor. Sewage workers; launderers; road sweepers; toilet, office, and hospital cleaners; sex workers; emergency-service crews; abattoir workers; pest controllers; and morticians suffer both from stigma and the stress of overcoming disgust. They find little sympathy and social support, as few stalwart friends are ready to hold extended conversations with them about the horrors that their professions force them to encounter. Professional support tends, again, to concentrate on dismissing disgust as irrational, rather than engaging with its real, and often powerful, effects on the psyche.

  The horror and shame of breaking rules of good manners affects youn
g women who reach the age of menarche. When I hit that transition, I stayed in my room, refused to go to school, and claimed to be sick for several days each month. Though there are few studies on this, it may be a common pattern. Many girls in developing countries drop out of school at this time.38 With little in the way of suitable toilet facilities and reliable sanitary napkins, girls live in fear of shame because toilet doors don’t close (if there are toilets at all), makeshift menstrual pads leak and can’t be washed and left out to dry in public, and boys tease. Faced with such problems, or even when there are menstrual-friendly modern facilities, girls the world over may prefer to sequester themselves in a sort of self-disgust when their periods start. Well-meaning NGO campaigns that seek to tell girls that they are behaving irrationally are again missing the point.39

  When Disgust Goes Wrong

  Like any of our organs, the disgust system and its components can malfunction. Genes, wiring, chemistry, physiology, and life experience can all conspire to make brains produce behavior that is maladaptive, interfering with the normal pursuits of everyday life. People at the top or bottom end of a normal distribution of disgust sensitivities might also find that they are classified as abnormal. Whether due to malfunction or finding themselves at an extreme end of a spectrum, many people have problems that relate to disgust. High levels of disgust make some people so squeamish that they can’t leave the house, eat, or make social contact properly, and low levels of disgust make people unhygienic, unmannerly, and hard to be around. The fact that disgust seems to be made up of a number of subcomponents suggests that we might find pathologies associated with each: food/animal, sexual, lesions, hygiene, other people, and contamination disgust. Do malfunctions in each domain manifest as specific phobias or anxieties?

  Obsessive-compulsive disorder (OCD) is an obvious candidate for a disorder of the contamination subcomponent of the disgust system.40 OCD patients suffer from an excess of disgust. Thoughts of contamination and impurity intrude into their daily lives, and they try to reduce their distress by sanitizing and disinfecting themselves and their environment.41 Sufferers describe how contamination is a constant concern—how they live in a world of spreading, looming contagion.42 Not surprisingly, the condition gets worse in the presence of a disease threat—psychiatrists report increased distress and the exacerbation of washing rituals during epidemics, such as the swine flu alert.43 And because OCD occurs along a continuum, it is likely that for every individual diagnosed, there are many more who suffer from some form of debilitating contamination anxiety.

  As ultrasocial beings, humans depend on others for survival, yet other people, as disease sources, are a key subdomain of disgust. Social phobias may therefore be related to other-person disgust. Though most phobias go unreported, at any one time 4.5 percent of Americans may be suffering from social phobias and 2.3 percent from agoraphobia.44 Abnormal unwillingness to venture into crowds and to contact other people is associated with heightened disgust sensitivity.45

  Other specific phobias also relate to components of the disgust system. Blood-injection-injury phobia is characterized by extreme aversion to the sight of blood, injuries, or surgical procedures, including injections. Sufferers rate disgusting images as more disgusting than control individuals do, and they display stronger facial expressions of disgust.46 Such sufferers would be likely to score particularly highly on our lesion subscale of disgust.

  Animals that have connections with disease and dirt are much more likely candidates for phobias and childhood fears than animals that do not (i.e., spiders, rats, worms, maggots, cockroaches, teeming insects),47 suggesting a disorder of the insect/animal disgust domain. Though there has been controversy as to whether spiders occasion fear or disgust, it now seems that disgust is a stronger predictor than anxiety of spider avoidance.48

  Trichotillomania may also be disgust related; people with a condition that involves the compulsion to pull out skin hairs may be responding in an exaggerated manner to the possible presence of ectoparasites in skin—a hypothesis that has some support in the literature.49 Another odd phobia has Internet groups dedicated to it. Trypophobia is fear of clusters of small holes. Looking at the images that trigger this phobia, I find I’m also scratching my skin and feeling slight nausea in sympathy with the phobics. To me the patterns of holes look like clusters of insect eggs, possibly laid in the skin. These patterns hyperstimulate my parasite detection mechanisms and creep into my nightmares. Look it up on the Internet if you dare check your own responses!

  Since food is one of the subdomains of disgust, one might expect food anxiety disorders to relate to disgust. Clinicians point out that anorexia and bulimia feature disgust, and some, but not all, studies have shown heightened disgust in food phobics.50 Meat is one of the most likely sources of pathogens in food and is also a special focus of anxiety. All cultures have taboos about what meats are suitable to eat, and vegetarians/vegans reject it entirely.51

  Since sex is a subdomain of disgust, one might expect pathologies of the disgust system to affect sexual function. Though the problem has been little studied, several authors report that disgust is implicated in undermining sexual arousal and desire.52 Clinicians recount case studies of women who had turned disgust on themselves, associating dirt, disease, fistula, and defecation problems with their vagina, leading to an inability to face intercourse.53 The UK broadcaster Stephen Fry describes why he chose celibacy in the following terms: “I would be greatly in the debt of the man who could tell me what would ever be appealing about those damp, dark, foul-smelling and revoltingly tufted areas of the body that constitute the main dishes in the banquet of love. . . . Once under the influence of the drugs supplied by one’s own body, there is no limit to the indignities, indecencies, and bestialities to which the most usually rational and graceful of us will sink.”54

  If the psychological problems that we have been talking about are pathologies of different components of the disgust system—of fomite, food, animal, sex, and other-people disgust—then we would expect some cross talk between conditions. A quarter of OCD patients in one study were found to be virgins, and 9 percent had not been sexually active for years.55 Many also suffered from extreme shyness, suggesting possible social phobia comorbidity with OCD.

  If these phobias can be explained as maladaptive overvigilance in the parasite-avoidance system, then are there also people with underresponsive disgust? It’s been suggested that one of the reasons that patients with Huntington’s disease can be hard to nurse is damage to the disgust system in the anterior insula.56 Caring for such patients is challenging when they pay little attention to their toileting and keeping themselves clean.

  Self-neglect is a common problem that social workers have to deal with, when clients’ poor hygiene manners leave them isolated, ignored, and sometimes abused by society.57 Indeed, I agreed to speak at a conference on this topic, but it was canceled—because too few people signed up to attend! Such disgusting topics are unpopular, unattractive, and neglected, as, indeed, are those who suffer. Individuals with learning difficulties have been shown to get a poor deal from the UK national health service. It is likely that people who have problems with personal hygiene—whether due to low disgust, autism, or some other issue—are likely to be discriminated against in all walks of life. This is one of the last bastions of social prejudice that needs investigation; funders and researchers should be encouraged not to turn their noses up at it.

  Beyond people’s having too much, or too little, disgust sensitivity, disgusting experiences can also cause psychological sequelae. Though post-traumatic stress disorder (PTSD) is generally thought of as being triggered by extreme fear, a companion condition is triggered by extreme disgust. Encountering decomposed corpses in war or at work, or other shockingly disgusting scenes, can lead to intrusive thoughts, flashbacks, recurrent nausea, and feelings of dirtiness that cannot be removed by washing—which can leave patients unable to lead a normal life.58 Similarly, rape victims with PTSD can suffer from fee
lings of dirtiness, described as “mental pollution.”59 Victims of childhood sexual abuse and survivors of torture may also suffer persistent lasting mental torture by disgust.

  Can anything be done to improve conditions for those suffering from disgust-related pathologies? I see good cause for hope. First, accurate diagnosis is required. Seeing such problems as part of an adaptive parasite-avoidance system can help hone the instruments of diagnosis and offer better means to test the effectiveness of therapies. Second, many of these conditions are part of a continuum in the population, with a somewhat arbitrary line dividing the “normal” from the “abnormal.” Many people may be suffering at levels that are subclinical, but because the conditions are associated with shame, they may be reluctant to seek help. Health workers need to be briefed to detect hints of these conditions and to look for comorbidities, for example, for sexual dysfunction in those presenting with OCD. Internet-based support for conditions like these may provide part of the answer. Discussing such conditions online may be easier for sufferers than in a face-to-face interaction in a clinic.60

  Third, there are many approaches to treatment, both through behavioral and drug therapies. A systematic look through the lens of disgust at what has worked in each of these conditions might reveal effective therapies. For example, we know that cognitive reappraisal is possible. Just as rotting milk can be relabeled as yogurt and so become palatable, exercises aimed at reappraising sexual organs, not as smelly and dirty, but as examples of exquisite design could be effective in reducing sexual phobias.61 Work is needed to determine the effectiveness of behavioral therapies such as exposure with response prevention (ERP) and microbiological experiments demonstrating the lack of organisms on objects perceived to be contaminated.62 Cognitive behavioral therapy (CBT) involving habituation to disgust objects, extinction of negative associations, and the formation of new and positive associations could be used across these phobias, possibly with the addition of cortisol, which has been shown to enhance the consolidation of newly learned memories.63 If pathologies relate to disgust subsystems, it is vital that the right set of stimuli be used for habituation. Drug therapies might also focus on the possible implication of serotonin pathways in disgust.64