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Nina Strohminger, perhaps not unlike many fans of raunchy comedies and horror flicks, is drawn to disgust. The University of Pennsylvania psychologist has written extensively on the feeling of being grossed out, and where it comes from. The dominant idea, developed by Paul Rozin and April Fallon, is that disgust evolved adaptively from an oral revulsion to biologically harmful substances, like rotten food and bodily waste. The emotion subsequently crept into the social arena, they claimed, as we became revolted by abnormal and licentious behavior. Moral repugnance arose as a result, which retains little if any connection to the biological origins of disgust. It’s “like a parfait,” Strohminger says. “It started out as one thing and things kept getting added on as it developed.”

Building on Darwin’s 1872 thesis that disgust signified “something offensive to taste,” Rozin and Fallon’s theory made disgust one of the more popular human emotions to study. Strohminger finds their story intuitive, although perhaps oversimplified. In particular, she worries that the cumulative view of disgust masks a more evolutionarily complex story. Strohminger prefers to approach disgust not as a straightforward extension of the immune system’s aversion to harmful substances, but as “a psychological nebula, lacking definite boundaries, discrete internal structure, or a single center of gravity.”

Disgust is inherently ambivalent—it at once revolts and attracts us. This reflects, for Strohminger, the larger evolutionary ambivalence that disgust stems from, since we “must balance the need for nutrition against the peril of toxic comestibles, the need to socialize against the threat of communicable disease.” In short, disgust may not derive from a simple aversion to harmful substances but from a tension between the desire to explore and consume new things and the dangers of doing so.

There’s more to the story of disgust than being biologically revolted by harmful substances.

Josh Rottman, a developmental psychologist who specializes in disgust, claims that the emotion is better understood by examining the social forces that inform it. If disgust were an adaptive behavioral mechanism for avoiding biologically harmful substances, Rottman argues, children would exhibit disgust in their most vulnerable years, when their immune system is still developing. But infants and toddlers are willing to put just about anything in their mouths, even imitation feces, and only begin to show signs of disgust around ages five to seven, long past their vulnerable weaning period. This could, perhaps, be explained by the fact that children’s immune systems benefit from their exposure to a variety of substances. However, most of the helpful bacteria and immune-building germs that children encounter come not from steaming mounds of dung and worm-eaten corpses, the hallmark triggers of disgust, but rather from invisible air and water-borne pathogens.



Rozin attributes the delayed onset of disgust to the omnivore’s dilemma, the fact that we must balance our ability to consume a wide variety of foodstuffs with the potentially steep consequences of poisoning ourselves. If disgust had a single adaptive origin, one might expect certain substances to universally elicit disgust. But universally disgusting objects don’t seem to exist.

While some Westerners are disgusted by insect larvae on a plate, Easterners are similarly revolted by the idea of lifting curdles from soured milk, adding salt, and giving the resulting product a quaint name like “cottage cheese.” The Hazda of Tanzania often consume putrid meat scavenged from lion kills. Shamans of the Koryak tribe in Siberia consume mushrooms, urinate in a pot, and pass it around for the group to sip. And the Mundari tribe in South Sudan not only showers in cow-urine but also cover their bodies with ash from dung fires to ward off infection.

Given this ethnographic variation on disgust, Rottman argues that what elicits the emotion is largely socially informed. There’s even considerable variation for disgust within a lifetime, as we can develop a taste for bloody, organ-spilling horror films as well as revulsions to odors of liquors we formerly enjoyed but once overindulged in.

Since disgust arrives in middle childhood (ages five to nine), right around the time when social biases are formed, Rottman says, “It seems to be more of a social avoidance kind of emotion. It helps us avoid people, not only people who are sick, but also people exhibiting non-normative behaviors.” We’re not only disgusted by people who are boiled and plagued, who pose a threat to our physical health, but also by people who seem socially ill, who pose a threat to our customs and morals.

Moral repugnance is perhaps the most complicated iteration of disgust. Daniel Kelly, a philosopher at Purdue University who wrote a book on the subject, considers disgust to have more cognitive than sensory signatures. “Distaste is sensory, a revulsion to something that tastes harmful,” he says. “But disgust isn’t merely sensory—charred human flesh might be delicious, but that’s not why we don’t eat it.” Kelly argues that the emotion shouldn’t have any authority in moral evaluation. “There’s too much cultural variation, and it’s too easily triggered by stuff that’s morally irrelevant” to have a place in moral judgments (after all, some people consider body hair, tight clothing, and even certain colors disgusting). Consequently, Kelly finds there is no “deep wisdom” in disgust, and the use of moral repugnance in decision or policy making is irresponsible and even dangerous. “Disgust tends to stigmatize and dehumanize its object, including people,” Kelly says. “It makes it easy to treat people horribly.”

Plato was perhaps the earliest to think seriously about disgust. Leontius, a character in The Republic, is torn by an embarrassing desire to feast his eyes on corpses piled along the perimeter of Athens. Eventually overcome by his ghastly fascination, Leontius runs toward the corpses and wails, “Look, you damned wretches, take your fill of the fair sight!” Plato presents this as an instance of the tormenting conflict in the soul between reason and unruly, often objectionable desires. While it may seem strange to take disgust as a symptom of a cursed soul, Plato’s story does highlight the chief difficulty about disgust, namely, that we’re attracted to it (and sometimes even disgusted with ourselves because we’re attracted to disgusting things). Rozin used the term “benign masochism” to denote how we enjoy laughing or crying at movies when there’s little risk involved. “It’s one thing to enjoy toilet humor,” Strohminger writes. “It’s another to be inside the toilet.”

What perplexes Strohminger is our attraction to aversion. “We need to account for the fact that we chase after disgust,” she said. Our attraction to disgust is hardly modern. The grotesque fascinated painters from the Renaissance to Goya, with his visages of Saturn, and Francis Bacon, with his distorted portraits. Even earlier, the ancient Greeks told gut-wrenching stories about how Atreus killed and cooked his brother Thyestes’ children and fed them to their unwitting father. Perhaps disgust is cathartic to enjoy when there’s no real threat of contamination, just like it’s cathartic to feel the rush of heart-pounding thrillers or tragedies. Or perhaps Plato was right to say that disgust was contrary to reason, something that we just can’t explain. As a matter of taste, disgust is inherently subjective. There’s no real reason why one person might crave bacon-flavored ice cream with pickles while the thought of that might make another retch. And that might be why it’s hard to explain why we chase after disgust, too. In the end, we might have just developed a taste for it.

Marco Altamirano is a writer based in New Orleans and the author of Time, Technology, and Environment: An Essay on the Philosophy of Nature. Follow him on Twitter @marcosien.