*Originally published on December 12, 2023.
In a hangar-like building just outside Halifax, Greg Wanger, founder and CEO of Oberland Agriscience, digs his hands into a rubbermaid tub filled with black soldier fly larvae.
“I have done this many times,” Wanger says, pulling up a brimming handful of gently writhing larvae.
“But there are people that this is just a little bit too much for them, and I fully understand that.”
This facility — an insect farm, one of only a few in Canada — uses the larvae of several hundred million black soldier flies to produce more sustainable forms of pet food, fish feed and other products. But while many cultures consume insects as part of their diets, they are seen as disgusting fare by others, especially in the West.
“What we typically do with disgust is we push it away,” he said. But with demand for protein rising, he says we need to push back on attitudes that cast insects as disgusting.
“We can’t do that, the way our society is going now.”
This is one of the mysteries of disgust. While theorists have argued it’s an evolutionary impulse that has helped keep humans safe from poisons and pathogens — and maybe form part of what defines humanity itself — it’s also been co-opted by culture, driving everything from our sense of what foods are fit to eat, to religious and political divides.
In an increasingly fragmented world, it’s important to understand how disgust affects us — and to recognize what kind of realities it’s used to create.
Disgust’s evolutionary role
Theorists argue disgust played a key role in humans’ evolutionary trajectory. On the one hand, disgust helps humans avoid eating things that might make them sick, said Daniel Kelly, philosophy professor at Purdue University and the author of Yuck! The Nature and Moral Significance of Disgust.
On the other hand, Kelly said, disgust serves on the front end of the immune system, directing people away from communicable diseases — an explanation for why the sight of someone sneezing is disgusting.
But human disgust is ultimately a blunt instrument, said Kelly — and that means it’s more likely to produce false positives than false negatives.
“So we could become disgusted by things which in fact aren’t poisonous, or in fact aren’t parasitic but the system itself is going to err on stay[ing] away from that thing.”
Irrationality of disgust
Some of the most vivid examples of this are in the work of psychologist Paul Rozin, the pioneer of the field that’s come to be known as ‘disgust studies.’
Prior to Rozin’s work, little research had been done in disgust, and many dismissed it as a primitive emotion.
But Rozin saw something complex in the way disgust worked. For instance, he wondered why so many people are disgusted by the idea of eating anything but the muscle of an animal, even though millions of people consume meat every day? And why, particularly in the West, do we limit ourselves to eating about 3 or 4 mammals?
That led to a series of experiments in which Rozin tested the ideational nature of disgust, applying the idea of sympathetic magic, which had originated in early 20th-century anthropology.
It includes the belief that things that have been in contact can have a lasting effect on each other, even if the contact is brief. Rozin wanted to better understand how this concept could play out in psychology.
Through a series of experiments — including one where participants were offered a cup of juice in which a dead, sterilized cockroach had been dipped — Rozin tested how even brief contact with something disgusting rendered something gross — despite the fact that there was no actual disease risk — known as the law of contagion.
“It has nothing to do with infection,” he said. “It has to do with a cockroach that was pressed into that food. And if you take it in, it’s disgusting and you’re defiled by eating something disgusting.”
Rozin also tested a principle known as the law of similarity, meaning “if it looks like an X, it’s an X.” He offered participants a wide range of things that looked like something disgusting — including chocolate fudge shaped like dog poop. Even knowing it was delicious chocolate, most refused to eat it.
Animals and disgust
While some psychologists say disgust is an uniquely human trait, other scientists have argued it also manifests in animals.
Cecile Sarabian, cognitive ecologist and research fellow at the Institute for Advanced Study in Toulouse, France, has studied disgust in primates. She found Japanese macaques are more reluctant to eat a piece of grain placed on top of macaque feces — even when those feces are fake — and chimpanzees will recoil at the touch of something slimy, similar to the reaction shown by humans.
Sarabian says the elements of the distinctive human expression of disgust — the so-called ‘gape face,’ which features lowered eyebrows, a wrinkled nose and a raised upper lip — is also shared with macaques and mice.
“I think over the years, and particularly, I would say, over the last five to 10 years…we have accumulated more and more evidence from the animal literature that what we would describe as being uniquely human is actually present in most species.”
Disgust’s harmful effect on society
Nonetheless, what does seem uniquely human is in how disgust has been co-opted to serve cultural purposes.
Senthorun Raj, associate professor of human rights law at Manchester Law School, says disgust can be seen at work in the history of criminalization of homosexuality in the U.K., from the 1533 Buggery Act introduced by Henry VIII, to the 1895 trial of Oscar Wilde for gross indecency.
“Here you have a law that actually institutionalizes ‘gross’, and obviously, the use of gross might be slightly different to how we’re using it now. But I think it’s vernacularization today actually echoes the way it was institutionalized then, because it was really about expressing this kind of moral repudiation — spitting out of certain sexual behaviours and bodies of the people who engaged in these behaviours from society,” Raj said.
These days what seems particularly concerning is how disgust is being more and more used for political purposes to demonize any group who is considered the other, said Raj.
“Governance through disgust is not unusual. And there’s sort of this scapegoating of particular communities, the kind of targeting of particular people as morally reprehensible, disgusting, aberrant, monstrous, we see that playing out in global conflicts right now.”
Because disgust is so powerful and so sensitive to social factors philosophers like Daniel Kelly have argued that we should resist disgust’s effect on social and moral judgments.
“It’s not a guide to moral reality,” said Kelly.
But at a time of heightened social and political divides, understanding how disgust can be both a force for survival — and can make the world more dangerous — can play a role in reckoning with its influence.
“We’re all emotional creatures, and disgust is one of those very pervasive emotions like shame that you just can’t get rid of, no matter how hard you try. So what can we do?” asked Senthorun Raj.
“Well, we should think critically about what our emotions are doing, and be mindful of the politics that they organize.”
Listen to this episode by downloading the CBC IDEAS podcast from your favourite app.
*This episode was produced by Moira Donovan, with help from Mary Lynk.
Guests in this episode:
Greg Wanger is CEO and founder of Oberland Agriscience.
Rachel Herz is a Canadian-American neuroscientist who teaches at Brown University, and is the author of That’s Disgusting: Unraveling Mysteries of Repulsion.
Daniel Kelly is a professor of philosophy at Purdue University, and the author of Yuck! The Nature and Moral Significance of Disgust.
Paul Rozin is a professor emeritus of psychology at the University of Pennsylvania.
Cecile Sarabian is a cognitive ecologist and Research Fellow at the Institute for Advanced Study in Toulouse, France.
Parama Roy is professor emerita of English at the University of California, Davis, and the author of Alimentary Tracts: Appetites, Aversions, and the Postcolonial.
Bill Miller is professor emeritus of Law at the University of Michigan, and the author of The Anatomy of Disgust.
Senthorun Raj is an associate professor of human rights law at Manchester Law School.
David Pizarro is a professor of psychology at Cornell University.
*This episode was produced by Moira Donovan, with help from Mary Lynk.
Listen to the full episode by downloading the CBC IDEAS podcast from your favourite app.
