The Disgust Dilemma: How Evolution’s Most Primal Emotion Shapes Our World

Imagine sitting at a kitchen table, staring at a cricket. Would you eat it? For most, the answer is a visceral “no.” But why?

This question unravels a complex web of biology, culture, and economics—centered on disgust, an emotion as ancient as humanity itself. From fecal matter to fried insects, disgust has shaped human survival, diets, and even moral judgments. Yet, as researchers reveal, this primal instinct might also be holding us back from solving modern crises like food insecurity and climate change. Let’s dive into the science, stories, and surprises behind disgust.

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The Evolutionary Roots of Disgust

Disgust evolved as a defense mechanism against pathogens. Val Curtis, a pioneering “disgustologist,” discovered that universal triggers—feces, vomit, rotting food—all link to disease risks. Her research revealed six categories of disgust:

1. Hygiene (e.g., unwashed hands):
   • Public restroom surfaces (e.g., door handles, toilet seats) — perceived as contaminated and teeming with germs.
2. Animals/Insects (e.g., cockroaches, ants):
   • Maggots in rotting food — their association with decay and disease triggers visceral revulsion.
3. Sex (e.g., “unclean” practices):
   • Infidelity or “dirty” fetishes — actions violating cultural norms of sexual “purity” (e.g., taboo acts in conservative societies).
4. Atypical Appearance (e.g., wounds, bleeding):
   • Severe burns or disfigurements — deviations from “normal” human features often provoke instinctive avoidance.
5. Food (e.g., spoiled meals):
   • Expired dairy products (e.g., curdled milk, moldy cheese) — their sour smell/texture signals potential harm.
6. Moral Violations (e.g., corruption):
   • Child abuse — actions deemed universally reprehensible, evoking moral disgust and outrage.

Paul Rozin, a psychologist who sparked modern disgust studies, notes that meat—a prized food—is also the most taboo. “Disgust is a rejection of contamination,” he says. A cockroach in your sundae isn’t just gross; it taints the entire treat.

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Cultural Variability: Dog Meat, Horse Steak, and Human Flesh

While disgust has biological roots, culture dictates its targets:

• In California, eating horse is illegal; in some parts of Europe, horse butcheries thrive.
• Rozin admits he’d try dog meat or roadkill out of curiosity—and even human flesh. “I’m curious what it tastes like,” he says.
• Endo-cannibalism (eating loved ones) versus exo-cannibalism (eating enemies) reveals how context flips disgust into reverence or revenge.

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Disgust’s Double-Edged Sword

When Disgust Saves Lives

• Curtis’s handwashing campaign in Ghana used disgust to slash disease rates. A video showing fecal contamination in food doubled handwashing rates for years. Graphic anti-smoking ads (rotten lungs, blackened teeth) similarly exploit disgust to deter harm.

When Disgust Harms Progress

• Recycled water: Though safe, people reject it due to its sewage origins.
• Insect protein: Over 2 billion people eat insects globally, yet Western disgust persists. The U.N. touts insects as a sustainable protein source, but stigma blocks adoption.

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The Economics of Eating Bugs

Economist Sandro Ambuehl tested disgust’s flexibility through insect-eating experiments:

• Price of disgust: College students demanded U$200 to U$300 to eat a scorpion. Economist Sandro Ambuehl paid college students to eat scorpions. Higher incentives made subjects seek positive info, rationalizing their choice. But bribes rarely lead to long-term acceptance.
• Incentives warp judgment: Higher payouts made subjects seek positive info (e.g., “Why Eat Insects?” videos). “Incentives can cause bad decisions,” Ambuehl notes—or rational ones, depending on perspective.
• Mere-exposure effect: Medical students overcome cadaver disgust; Ambuehl began snacking on crickets mid-experiment.

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From “Ick” to “Incredible”: The Future of Food

Could insects go mainstream? Emily Kimmins of Kraft Heinz sees potential:

• Stealth integration: Cricket flour in protein bars or chocolate (the FDA allows 60 insect fragments per 100g of chocolate).
• Marketing tricks: Call it “konchu” (Japanese for insect) or pair with familiar flavors (e.g., chapulines grasshoppers in guacamole).
• Cultural shifts: Sushi and edamame were once exotic. “When in doubt, cover it with chocolate,” Kimmins laughs.

Yet barriers remain. Kraft Heinz rates insect-based foods a “7” on the difficulty scale. Cost, scalability, and the “ick factor” loom large.

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A Legacy of Disgust

Val Curtis, who linked disgust to disease avoidance, died in 2020. Her work lives on in hygiene campaigns and insect advocacy. Paul Rozin, now promoting black soldier fly larvae, remains optimistic: “If people didn’t know what they were eating, they’d think it was good”.

The Black Ant, a NYC insect restaurant, closed in 2023—but not before serving grasshopper croquettes and ant-flecked guacamole. As Rozin says, disgust is malleable. What’s revolting yesterday (sushi, recycled water) may be mundane tomorrow.

Disgust is a survival tool turned stumbling block. To tackle 21st-century challenges, we must rethink what’s “gross”—or risk missing solutions hidden in plain (six-legged) sight.

Curious for more? Dig deeper into the science of our references:

Ambuehl, S., 2024. An experimental test of whether financial incentives constitute undue inducement in decision-making. Nature Human Behaviour, 8(5), pp. 835-845.

Ambuehl, S., 2017. An offer you can’t refuse? Incentives change what we believe (No. 6296). CESifo Working Paper.

Curtis, V., Aunger, R. and Rabie, T., 2004. Evidence that disgust evolved to protect from risk of disease. Proceedings of the Royal Society of London. Series B: biological sciences, 271(s.4), pp. S131-S133.

Freakonomics radio: The Downside of Digust, 2021 (2025). Available at: https://freakonomics.com/podcast/the-downside-of-disgust-update/

Rozin, P. and Fallon, A.E., 1987. A perspective on disgust. Psychological review, 94(1), p.23.