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We have just made the entire Freakonomics Radio archive available, free, on every podcast app. That’s more than 10 years’ and 400 episodes’ worth. Hopefully you’ll enjoy poking around the archive. And tell your friends! You listeners often write in to ask how you can help our show. One thing you can do is spread the word. Or: leave a review or a rating on your favorite podcast app. That’s a great way to help other people discover Freakonomics Radio. Our preference is the five-star rating. If you’re inclined to leave fewer than that — well, let’s just forget we had this conversation. The important thing here is that the entire archive of Freakonomics Radio is now available to you, and anyone, free, on any podcast app. And here now is the newest addition to our catalog, Episode No. 448. Hope you enjoy.

If you sat down at my kitchen table and I put an insect in front of you — maybe a cricket or a grasshopper — would you eat it? If you answered “no” — and I’m guessing you did — then why not? Your answer likely has something to do with “disgust.” But have you ever wondered why eating an insect is disgusting? Have you ever wondered why disgust exists? And what else do you find disgusting? Are there any universal disgusts?

Val CURTIS: Fecal material, for example, is inherently disgusting. Every person on the planet, with a few strange exceptions, finds fecal material something they want to stay away from.

But once you get past poop, absolutes are hard to find.

Paul ROZIN: There are enormous variations in disgust. 

Consider, for instance, the animals we eat and don’t eat.

ROZIN: I’m a massive dog lover, but I would eat dog out of curiosity.  

Sandro AMBUEHL: In California, you cannot eat horse. Whereas in many European countries, you have horse butcheries. 

ROZIN: I’ve never eaten roadkill, but I would. I would eat human flesh.  

From an evolutionary standpoint, disgust has often served us well: there is good reason to not eat poop — as well as other disgusting things that might harm us.

CURTIS: There’s this real [gasp] moment. 

But what if I told you that disgust is also holding us back? That it prevents us from pursuing strategies that could improve the environment, the economy, even our health?

Iliana SERMENO: Just try them. They’re not as disgusting as they look. 

Today on Freakonomics Radio: we’ll explore the roots, and types, of disgust.

CURTIS: There’s basically six different types of disgust.

How incentives may change your disgust threshold.

AMBUEHL: I brought buckets and tissues. I was afraid that somebody might throw up. 

We look into what psychologists call the “mere-exposure” effect:

ROZIN: Medical students are disgusted by cadavers. But after they’ve dissected a cadaver, they’re much less disgusted.  

And we ask what it might take to overcome:

Emily KIMMINS: When in doubt, cover it with chocolate.

*      *      *

We begin with someone who’s an elder statesman — and a pioneer.

ROZIN: Nobody studied disgust 50 years ago. I did sort of start the modern interest in disgust. I mean, Darwin wrote about disgust quite a bit.

That’s Paul Rozin.

ROZIN: R-O-Z-I-N. People call me Rosen, but that’s not right.

Rozin is one of two scholars of disgust we’ll be hearing from today. He’s a professor of psychology at the University of Pennsylvania. 

ROZIN: Much of my work is about how humans relate to food from anthropological, evolutionary, and psychological perspectives. 

It was Rozin who we heard say in the open of this episode that there are “enormous variations in disgust.”

ROZIN: You have people who have almost no disgust. They certainly wouldn’t eat feces, but they’re not really disgusted by seeing animal feces or something like that. And there are other people who will not blow their nose in a brand new piece of toilet paper.

Because, you know, the poop association. As for Paul Rozin’s personal disgust levels:

ROZIN: I’m probably in the 20 percent of people who are least disgusted.

Stephen DUBNER: Are there things that you are particularly disgusted by that aren’t the common ones?

ROZIN: Yeah, and I’m puzzled by it. I don’t like really stinky cheese. 

Rozin calls himself a “partial vegetarian.”

ROZIN: I do not eat mammals or birds. However, I have a whole bunch of exceptions. For example, I will eat bacon. I will eat rejected food. So, if someone’s in a restaurant with me, and they eat a hamburger and they only eat half of it, I, in principle, will eat it, because it’s going to go in the garbage. I will eat calves’ liver, which I love, in the United States because it’s a waste product. Nobody kills a calf for the liver.

It was also Rozin who noted in the open of this episode that he would eat dog, roadkill, even human flesh.

ROZIN: I’m curious what it tastes like. Whether I’d be disgusted by it — I don’t think so but I could be.  

DUBNER: I’ve always wondered what parts of the human do you think would make for the best eating?

ROZIN: Well, we in the United States only eat muscle. In other countries they eat liver; they eat a lot of the viscera. I don’t terribly like eating brain, though I have eaten brain and it doesn’t taste bad. I have eaten the ashes of one of my dear persons. That’s the idea of endo-cannibalism: you love somebody, and if they die, you want to keep them, in some sense, in your body — whereas exo-cannibalism, which is very different, is eating your enemies.

DUBNER: Would you like to see endo-cannibalism, as you’ve just described it, become more popular? 

ROZIN: I have no desire for that, but if a religion practiced it — I don’t think any current major religion does — I would think that’s okay.

Disgust doesn’t exist in a vacuum; it has ramifications.

CURTIS: So, people who are very high on the disgust scale often have comorbidities with other sorts of neuroticisms. So, we found, for example, that people who were high on disgust are also high on sex disgust and that makes it very hard to make a lasting bond in a relationship.

That is the other scholar of disgust we’ll be hearing from today.

CURTIS: I am Professor Val Curtis. I’m a disgustologist.

In Curtis’s case, that means a background in engineering, public health, and evolutionary anthropology.

CURTIS: I work on hygiene, sanitation, and water at the London School of Hygiene and Tropical Medicine. 

DUBNER: How does one become a disgustologist, and is that a large field? 

CURTIS: There are very few disgustologists in the world. Surprisingly, there are not hordes of people screaming to study the science of disgust. But there are a growing number. 

DUBNER: And what got you into the disgust racket? 

CURTIS: It was a long, long journey. But there was a eureka moment that got me traveling this route. So, I’d been working on trying to understand behaviors that made people sick, mostly in developing countries, trying to understand why people were hygienic or weren’t hygienic. For example, we’d done interviews in lots of different countries and I was asking people, “So, when would you wash your hands?” And they would say, “Well, when they feel sticky and disgusting.” And I go, “Well, what do you mean, ‘disgusting?’” And I kept coming up with these lists of things that people all around the world found disgusting. And it was a motley collection of things. I couldn’t figure out what connected that all together.

But then a colleague asked me to explain the cause of a strange parasitic disease. And I looked it up in a book about communicable diseases. And suddenly I realized all these things that people found disgusting were sitting in the index to this book. And I’m going, hang on, vomit. People find that disgusting. It makes you sick. Fallen hairs. People find that disgusting. Well, it’s a cause of ringworm. Food that’s gone off. That can cause typhoid, can cause diarrheal diseases. And the more I looked into it, the more I realized that there was a very obvious pattern here, that the things that everyone around the world seemed to regard as disgusting, they were all things that might harbor parasites and pathogens and so might make us sick. Being an evolutionarily-minded sort of person, I saw that this was basically an adaptation — something we have in our brain to make us behave in ways that avoid us getting sick.

Paul Rozin agrees.

ROZIN: The core of disgust is almost certainly originally derived from a system to avoid pathogens, which are usually part of animal food, not plant food.  

And that’s what led to his interest in disgust.

ROZIN: What got me interested is that meat is the most favored food of humans, and also the most tabooed food. So, I got curious why we should have such a strong negative emotion about a food that is highly nutritious and highly favored. 

DUBNER: Can you quickly define disgust for me ? 

ROZIN: Disgust was originally defined as a rejection or offense at the oral incorporation of an offensive substance. We added to that definition the fact that that substance is usually contaminating. That is, if it touches an otherwise-desired food, it renders it inedible. So, when a cockroach touches your sundae, that’s the end of the sundae. 

CURTIS: it turns out there are different categories of things that might make us sick that we find disgusting. 

Six categories.

CURTIS: There’s disgust about hygiene. There’s disgust related to certain types of animals and insects. There’s disgust related to sex. Disgust related to people who are atypical in their appearance — deformed or “not normal” tends to unfortunately evoke a sense of disgust. If you meet somebody with a lesion, with an infected wound, people do tend to find that disgusting. Types of food, particularly food that smells funny or has gone off. Those are the six disgust categories. 

So, those are the categories of things that generate disgust. What about our responses? We’ll start with the physical ones. The first is called the “disgust face.”

ROZIN: There are actually two disgust faces. One of them is a jaw drop, sometimes with the tongue sticking out, which is an oral rejection, and maybe a closing of the nostrils. Okay? There’s another one, which is primarily a raising of the upper lip, and that overlaps a little with the anger expression. 

And then there are the verbal expressions of disgust.

CURTIS: So, I’ve got a collection of the words from all over the world, and it’s quite surprising how many use this onomatopoeic “blech” or “ick” or “ugh” — it does seem to be almost a universal language. It’s to do with the gorge rising. It’s to do with this idea that your body is preparing itself for the ingestion of something that might make it sick. 

DUBNER: So, you’re saying that that “yekh” or “blech” or whatever, is literally a pre-vomit sound, yes? 

CURTIS: Yes. And everybody would understand it, wherever you were in the world.

But beyond the physical expressions of disgust, there is an emotional component. Which goes beyond the things we put in our mouths.

CURTIS: So, my definition of disgust is a system that evolved in the first place to help us avoid parasites and pathogens. But when you’ve got a system like that that is so useful, and we use the same neurons to detect social disgust and moral disgust as we do to detect pathogen disgust I think it’s reasonable to call it the same thing. 

ROZIN: That area is not as well-defined, and so there’s a big discussion now in moral psychology of the extent to which disgust is really a moral emotion.

DUBNER: When someone says that they are, “disgusted” by another person’s actions — something they consider immoral or unethical, maybe cruel — is that something that you consider disgust? An extension of the food disgust? Or is it more, in your view, metaphorical?

ROZIN: Well, that’s the big issue, whether it’s metaphorical use of disgust or it’s actual disgust. And one critical issue there is whether the same brain area is involved, for which there is some evidence, and also whether some of the other features of disgust even a little sense of nausea is involved. It does seem that when moral violations are called “disgusting,” they often have a bodily component to them. Like an axe murderer, not a bank robber.

DUBNER: But what if I say I’m disgusted by the actions of, let’s say, a politician. What he did disgusts me. I can’t imagine there’s actual nausea attached to that, for instance.

ROZIN: Well, I would say that’s a more metaphorical use of disgust. When we say someone who steals, someone who is corrupt, is disgusting, that’s a little different from saying that someone who, say, burns the American flag is disgusting.  

CURTIS: So, disgust is but one of a functional set of motives that make us do the things that were good for our ancestors. And they’re there in all of us all the time. And they drive a huge amount of what we do, and it’s very poorly recognized that that is the complete and necessary set of motives you need to be a human being.

DUBNER: You’ve noted that people are much less disgusted by the notion of eating rotten food when they’re very hungry. Also, that people are less disgusted by certain sexual matters when they’re aroused. So, how malleable is our disgust system? 

CURTIS: Our motives compete for our attention at every moment. And the one which is the strongest is the one that’s going to win. So, if it’s been a long time since you’ve had a — what am I allowed to say on the radio? 

DUBNER: Anything. 

CURTIS: Since you’ve “had a shag”? Can you say that? 

DUBNER: We don’t say that, but you can, sure.

CURTIS: So, if it’s a long time since you’ve had a shag, you’re going to be much more likely to be attracted by the somewhat smelly, greasy hunk who’s proposing himself to you than if you had a good one the day before. So, it’s not your level of disgust that’s going up and down. It’s the trade-off that you’re making that’s going up and down. If you haven’t eaten for weeks, the sandwich that has got mold on it — you might scrape the mold off, but you’re going to eat it.  

Okay, what have Val Curtis and Paul Rozin taught us so far? Disgust is driven by biological and quite likely evolutionary factors; it’s got strong emotional components. It’s also malleable — and variable, among individuals and cultures. The next question is: how useful can disgust be? Considering it is an ancient force and that we’re living in a modern world, should we learn to dial down the disgust in some cases? And are there other cases where we might want to turn up the disgust?

CURTIS: So, yeah, it is a double-edged sword.

Think about infectious disease, one of Val Curtis’s specialties.

CURTIS: So, globally, some of the biggest killers are infectious diseases.

As the Covid pandemic has reminded us, hand hygiene is an excellent weapon against infectious disease.

CURTIS: We’ve been working in programs all over the world trying to get people to wash their hands.

But let’s be honest: the benefits of hand hygiene have been known for a long time now. Some people just aren’t very diligent. So, Curtis got to wondering if she could apply what she’d been learning about disgust:

CURTIS: We used disgust to promote hand hygiene in Ghana. We did it not by talking about germs, not by talking about disease, but by making a very attractive little video where a rather well-dressed but typical Ghanaian woman came out of the toilet. And you notice that she doesn’t wash her hands. And then she prepares food for her kids. And you see her kneading this pounded yam. And you see stains of something indeterminate on the pounded yam. And then you see her feeding a piece of it to her child. And there’s this real [gasp] moment as moms watch this ad, they realize basically that the feces that she was dealing with in the toilet have actually got into the mouths of the kids. So, it’s a really powerful disgust message. 

DUBNER: Okay, so powerful I’m buying. Was it effective? Did it change behavior?

CURTIS: This is one of the most effective hand-washing campaigns ever. The rates of hand-washing more than doubled and they were still high several years after the campaign.

So, that’s a case where dialing up the disgust was fruitful. Another example: those horribly graphic anti-cigarette ads you may have seen, with rotten teeth and blackened lungs. But let’s now consider the flip side. Rather than exploiting disgust in order to promote a certain behavior change, are there other behavior changes that are best promoted by reducing disgust?

ROZIN: The answer is: yes. 

Paul Rozin again. 

ROZIN: For example, a lot of people will not drink recycled water, which is water which goes from sewage to pure water in a matter of minutes, by being forced through a membrane that only passes water. So, it’s pure water, but people are disgusted by it because they know it was in contact with feces. Now, that disgust is a barrier to acceptance of this, which is a very efficient way of delivering water. 

So, that’s a case where there could be large environmental and economic gains from ratcheting down the disgust — maybe even geopolitical gains, considering that water scarcity is a source of great friction in many places. There’s another disgust-related mission that Paul Rozin is even more enthusiastic about: getting people to eat more insects.

ROZIN: Especially in the developing world, where they’re short of protein. Insects are a great source of protein. And though more than a billion people eat insects regularly, there are many who could use that protein who don’t, and they’re disgusted by insects. 

As with recycled water, you can imagine the various gains from increasing the consumption of protein-rich insects — especially compared with meat, which is incredibly resource-intensive to produce. In 2013, the U.N.’s Food and Agricultural Organization published a report promoting insect-eating as an “especially relevant issue in the 21st century due to the rising cost of animal protein, food insecurity, environmental pressures, population growth, and increasing demand for protein among the middle classes.” And how would these insects be consumed?

ROZIN: There are generally two philosophies here. One is to make flour, which is a high-animal-protein flour that replaces wheat or corn flour. At low levels you wouldn’t even taste it. So, that’s one approach: as it were, sneak it in. And the other approach is to say, “No, here are insects.” 

As Rozin notes, more than a billion people around the world already eat insects.

ROZIN: And they don’t typically make flour. They will typically cook the insects, maybe on a grill, or they’ll mix them in with other foods, but the insects are usually apparent. 

DUBNER: And what are the most popular insects?  

ROZIN: Often beetles, things like mealworms, larvae of insects, and grasshoppers. So, in Mexico — chapulines is what they’re called — you can get a taco filled with grasshoppers. 

But a billion people eating insects leaves another six-plus billion not eating insects. Because — well, because they disgust us.

*      *      *

DUBNER: I would submit that most people in America wouldn’t want to eat insects.

CURTIS: You already do eat insects. You’re allowed to have five insect legs in a Hershey bar. 

DUBNER: I’ve heard that. 

CURTIS: Yeah, look it up. 

We did look it up — that, again, was Val Curtis, by the way — and according to the Food and Drug Administration, there’s actually an average of eight insect fragments per chocolate bar; anything up to 60 fragments per 100 grams is acceptable. As is a small amount of rodent hair. And have you ever eaten a salad? Or peanut butter, or canned tomatoes? Have you ever had a beer or a glass of wine? If so, then you’ve been routinely ingesting your fair share of insect all along. That said, most of us do not knowingly eat insects, especially in toto. Because they disgust us.

CURTIS: So, insects are one of the types of things that we tend to find disgusting inasmuch as how closely they’re connected with disease. 

Curtis, you will recall, is a professional disgustologist, with a background in public health and anthropology. I got to wondering whether the field of economics had anything worthwhile to say about disgust.

AMBUEHL: Economists don’t usually think about disgust. 

That’s Sandro Ambuehl, an economist at the University of Zurich.

AMBUEHL: They think, if anything, about moral repugnance, because that puts limits on what can be traded in markets.

Repugnance would seem at least moderately linked to disgust, as it often centers around the human body.

AMBUEHL: For instance, it limits how much you can pay people to participate in medical trials or surrogate motherhood or human-egg donation and so forth. There’s limits on the incentives that you can provide for these kind of transactions. But is it true that incentives lead to worse decision-making? We have all these laws that are based on this hunch. 

Laws against, for instance, compensating kidney donors. Or even offering compensation for breast milk.

AMBUEHL: It’s something that is empirically testable but hasn’t been empirically tested. So, that’s the main question that I want answered. 

He set out to answer this question with a set of experiments. Even though Ambuehl says he was thinking about repugnance, he plainly understands disgust. Because he built his experiments around the eating of insects.

AMBUEHL: Yeah, that’s right.

He used college students, of course, as his research subjects.

AMBUEHL: The way the experiment works is, people make decisions in five rounds, and each round was associated with one species of insect.  

He used mealworms and silkworm pupae and a variety of crickets.

AMBUEHL: House crickets, field crickets, and maybe the most disgusting ones are mole crickets. They are really nasty. In the beginning, I brought buckets and tissues. Because I was afraid that somebody might throw up. 

It turns out that didn’t happen. Maybe because the people who knew they’d throw up were the ones who opted out of eating insects during the experiment. Because you were given that choice. In one experiment, for instance:

AMBUEHL: There’s two groups of people. If you’re in the first group, you learn that you’re gonna be given $3 if you decide to eat five mealworms. If you’re in the second group, you’ll learn that you’re gonna be given $30 if you agree to eat five mealworms. Now, after you learn how much money you are given, but before you make a decision, you can choose between two videos to watch, to inform yourself about what eating these things is going to be like. One video is called “Why You May Want to Eat Insects.” The other video is called “Why You May Not Want to Eat Insects.”

Ambuehl wanted to measure how both financial and informational incentives affected the decisions his research subjects made. There was a separate experiment to see how much he’d have to pay students to eat a whole scorpion.

AMBUEHL: So, these are really large scorpions that are as big as your hand. And it takes about $200 to $300 to make college students eat those, or to make some college students eat those.

In the interest of scientific equity, Ambuehl ate one of these scorpions himself.

AMBUEHL: Take a plastic spoon, put a small shrimp on it, season it with some motor oil, and then eat everything, including the spoon. That’s about what eating a scorpion is like. 

What was Ambuehl trying to learn with this kind of experiment?

AMBUEHL: I wanted to know if I offer incentives to somebody, what do I do with their quality of decision-making?  

This goes back to the idea of whether financial incentives might skew someone’s judgment toward selling their kidneys or eggs.

AMBUEHL: What I’m interested in is whether, if I pay people a larger amount of money, are they going to be more interested in watching the positive video than the negative video? And it turns out the answer to that question is yes. 

In other words, the bigger incentive increases their appetite to persuade themselves that what they’re about to do is a good idea. Among the research subjects who were offered just $3 to eat the insects, around a third decided to do it, even without access to a video. Among the subjects who were offered $30, nearly 60 percent decided to eat the insects without video access, and more than 70 percent after watching the video about why eating insects is a good idea. So, what did this tell Ambuehl?

AMBUEHL: This result looks like incentives are causing bad decisions. 

But if you’re an economist, as Ambuehl is, these are in fact good decisions. How so?

AMBUEHL: If I offer you very little for doing something you might not like — well, what you want to make sure is that you don’t say yes by mistake. You’re okay with saying no because there’s not much to gain. Now, if I offer you a lot of money, saying no by mistake all of a sudden is quite expensive. And so, you become more interested in learning about the upsides rather than the downsides of the transaction. 

Now, how does this apply to Paul Rozin’s mission of getting people to eat more insects?

ROZIN: Well, economists, of course, love financial incentives, but there’s a problem. If you pay people to eat insects, they’re less likely to engage with it after you remove the payment. The fact that they’re being bribed to eat something may actually block getting to like it. Now, we don’t know how people get to like things. We still don’t know that. But it does seem that imposed incentives may block it — sometimes, but on other occasions they may not.

In other words, as all researchers like to say always: “further research is needed.” But with the incentives unclear, where does that leave you if your mission is to get people to eat more insects?

 AMBUEHL: In psychology, there’s this phenomenon called the mere-exposure effect. And what it says is just, as you are exposed to something over longer and longer time periods, you start liking it.

And Ambuehl had noticed, as he ran his insect experiments, that the mere-exposure effect was working on him.

AMBUEHL: As I was sitting there for a large number of hours putting insects into little plastic containers, I started snacking voluntarily on the house crickets.  

Rozin has seen several examples of the mere-exposure effect.

ROZIN: If you drink recycled water for a while — not too long, just maybe a week — you won’t even think about it anymore. The problem is getting over the disgust hump, because people don’t realize they’ll cease to be disgusted once they get used to something. We’ve shown that medical students are disgusted by cadavers. But after they’ve dissected a cadaver for a month or two, they’re much less disgusted.  

And Val Curtis has seen the effect.

CURTIS: In Uganda, we used to eat the flying ants that flew out once a year, and we’d catch them and fry them. They don’t really have much disease connection. And once you fried them and salted them and you’re having them with a few beers, the wriggly, sticky, gooey nature of insects is rather forgotten. So basically, people will eat insects that don’t have too strong a connection with disease. And the more you can distance them from a connection with disease, the more likely they are to eat them.

ROZIN: We know that if people eat insects for a while, not for too long, maybe even 10 times, they’ll get used to it and they won’t be disgusted. They don’t taste like meat, but they can be crunchy and a little nutty tasting. And so, the taste won’t put you off once you don’t find it disgusting. What has started is that small companies are making insects and they package them — one person I know puts them in dog food. So, that’s one way to get people to eat it, is to have their pets eat it first.

We’re looking at these various routes that we can use. A lot of Americans will try a cookie if you say it’s 20 percent insect flour. The biggest problem with getting insects more into the world is cost, because they’re not mass-produced. If we mass-produced insects, like if Pepsi-Cola or, Kraft or somebody, made a serious attempt to do this, they would produce insects on a large scale, they’d use all the tricks they use with cows to make it cheap to breed better insects. So, one of the problems is to convince a big company to say, “We’re going to go down this road because there’s a lot of business and potential public health.”

What would it take to convince one of these big food companies?

KIMMINS: My name is Emily Kimmins and I’m the senior manager of the sensory and consumer-science team for Kraft Heinz. 

Kraft Heinz being one of the world’s biggest food-and-beverage companies. They make Kraft mac-and-cheese, Philadelphia cream cheese, Oscar Mayer hot dogs, and dozens of other products you’ve likely run across.

KIMMINS: I’m in charge of the taste tests for any new innovations that are coming out across all the brands in U.S. and Canada. 

This means managing the company’s professional tasters.

KIMMINS: We can only ask our professional tasters to work for two hours because even though we use them as analytical instruments, they really are just human. So, if you ask them to taste more than 10 to 12 macaroni and cheeses in a two-hour period, it all starts to taste the same. And then we’ll do outside consumer panels in the evening. All we ask consumers to do is react. Just, do you like it? Do you not like it? 

Kimmins says that simply surveying consumers about a potential new product — something with insects, maybe — isn’t useful.

KIMMINS: Consumers need something physical to touch and taste and hold on to to tell you what they like and what they don’t like. And the more different things you can give them, the richer your information is going to be. 

So, when it comes to new food ideas, volume is important.

KIMMINS: Because it’s usually only about 10 percent that ends up making it out on the market. They may be really good ideas, but there’s something that gets in the way. There’s ingredients that aren’t available. It’s just too expensive to manufacture it. There’s consumers that are really interested, but not enough consumers to really make it make sense as a business. 

Okay, so when we say “insects,” Emily Kimmins of Kraft Heinz says — what?

KIMMINS: So, when you say insects, the first thing I want to know is what kind of insects? And the second thing I want to know is, do you have to see the insect? Can the insect be hidden? What form is the insect in? Maybe a worm can look happy and be, you know — maybe worms are okay. But cockroaches — never okay. And is it cricket flour? Or am I eating a physical, big old cricket? All of those things matter. And it also matters what we’re used to. So, depending on where you live in the world, eating insects might be completely fine, already part of my diet. “No big deal. Give me some more insects.”

AMBUEHL: Have you heard about the insect cheeses? 

That, again, is the economist Sandro Ambuehl.

AMBUEHL: There’s two somewhat well-known insect cheeses. In, I think, Sicily, they eat what’s called casu marzu—. 

Actually, it’s Sardinia where they eat casu marzu:

AMBUEHL: —which is a cheese that they let sit and then flies come and lay their eggs into the cheese, and then you have the maggots crawling around and people eat that cheese with the maggots.  

In some parts of Germany, meanwhile:

AMBUEHL: The Germans have mite cheese, so they have living mites in the cheese. 

Before you turn up your nose at the notion of eating insect cheese, especially if you’re an American, do you know what beef cattle raised in the U.S. are often fed?

AMBUEHL: It’s chicken litter. So, the feces of chicken are processed and are then fed to cattle and then you eat the cattle that have been fed on chicken s***.

All of this may or may not make the transition to insects more palatable for a company like Kraft Heinz.

KIMMINS: If we’re talking U.S. and Canada — the biggest concern is the ick factor. You need to understand how you can overcome the ickiness of the thought behind, “I’m going to be eating some insects.” That’s the biggest thing. We have to make sure we can get it into people’s mouths before they can judge whether they actually like it or don’t like it. One of the biggest tricks that we have is blending familiar with unfamiliar. So, if you can blend it with something that they already know, they already like, you have a better chance of getting new flavors into their repertoire. Like, new fruits combined with strawberries. You’ll see strawberry kiwi, you see strawberry goji berry, strawberry acai berry, because, “Well, I like strawberry, so I’m willing to try whatever the other new thing is, as long as it’s still with strawberries.” 

And of course not all consumers think alike.

KIMMINS: So, there are classic consumers that say, “Don’t touch my product, I love it. I want it exactly the way it is, I want it the same every time I get it, everywhere in the world.”

For instance?

KIMMINS: That’s a Heinz ketchup. “I want Heinz ketchup to always taste the same. It’s familiar, it’s comforting, it’s trusting.” 

So, we probably shouldn’t expect Heinz to be slipping any insects in their ketchup, at least knowingly.

KIMMINS: Then you have other consumers that might be more adventurous. Even Philadelphia cream cheese. They might be more adventurous consumers. They’re dipping stuff in it. Cricket cream cheese — it could be a thing.  

Does Kimmins really think insects are viable even for a big, mainstream company like Kraft Heinz? We asked her to rate the probability, with one being “definitely” and 10 being “no way.”

KIMMINS: I think for the general food world, it’s probably about a five, because there are people in the world that eat it. It is available, there are products that I can buy on the internet right now. It’s not that inconceivable. I think for Kraft Heinz, it would be a little bit harder. I think it would be at least a seven. But still possible. Yeah, it’s still possible. You’re not wasting your time. If you use a different language too, like, “Oh, this came from Japan” — like edamame. You know, those are soy beans — well, it’s edamame, it sounds fancy. I think that might be an actually brilliant way to do it. Make it sound exotic, make it sound adventurous. 

“Insect” in Japanese, by the way, is konchu. 

KIMMINS: It sounds great. A konchu brownie sounds delicious. 

And, of course, there is this classic move.

KIMMINS: When in doubt, cover it with chocolate. It always helps.

It’s also worth keeping in mind how tastes change over time.

KIMMINS: I have my great-grandmother’s recipe book and there’s a whole section on squirrels. And I would never think of making squirrel or serving it to my children today. But my mother and grandmother ate it all the time.  

So, what we find repugnant in one era may be standard in another. This concept holds not just for what we eat but what we believe, how we behave. Slavery, for instance, was for centuries treated like a standard business practice. On the other hand, consider life insurance. Until the middle of the 19th century, it was considered, as the sociologist Viviana Zelizer once wrote, “a profanation, which transformed the sacred event of death into a vulgar commodity.”

If we’re capable of making such big shifts in matters like these, can it really be so hard to make insects appealing? The European Union’s Food Safety Authority just ruled that mealworms are safe for human consumption, potentially clearing the way for a scaling-up of production, and supply. But what about demand? Sandro Ambuehl again:

AMBUEHL: I mean, judging from my own reaction and the reaction of many people I have seen, I do think it’s gonna be very, very hard to convince even a sizable minority of the population to consume insects on a regular basis. 

KIMMINS: I mean, no one thinks of kiwi or mango as being this very unusual food, but 50 years ago they seemed very odd and very scary. So, will crickets and mealworms and things like that eventually become mainstream? Partly, if they taste good. 

AMBUEHL: I mean, they’re not as disgusting as you’d think, but they’re just not very good. I think it’s much more likely that everybody would become a vegetarian than it is that people would start eating insects on a broad scale. But I do need to say, I think sushi was at a similar point in the U.S. a couple of decades ago.

KIMMINS: Things tend to start in restaurants first and then filter their way down, from fine dining to casual restaurants to fast food and then end up in retail. There’s always going to be adventurous people that are willing to try lots of different things. And then if it tastes good and they’re willing to say, “Hey, try this, it tastes good.”

SERMENO: Okay, so we have the guacamole. We add some insects. We add grasshoppers or black ants.

ROZIN: Right on top?

SERMENO: Yeah. They go on top.

DUBNER: Oh, boy. Wow.

SERMENO: Just try them. They’re not as disgusting as they look. 

ROZIN: If people didn’t know what they were eating, just tried this, they’d think it was pretty good.  

I met up with Paul Rozin — the Penn psychologist, scholar of disgust, insect advocate — at The Black Ant, a modern Mexican restaurant in Manhattan’s East Village. 

DUBNER: Are you hungry? 

ROZIN: I could eat. 

The chef is Iliana Sermeno.

SERMENO: We also have the chapulines dish, which is the grasshoppers with avocado and fresh cheese. We also have the chapulines croquettes, which we mix the croquettes and baby grasshoppers.

DUBNER: Can I prepare you one, Paul? 

ROZIN: Sure.

DUBNER: I’m going to give you a little bit bigger dose of ant than I—.

ROZIN: How many ants are you giving me?

DUBNER: That looks to be about a hundred ants. Wouldn’t you say, maybe? They’re pretty small.


ROZIN: This may be a good percentage of my total ant.

DUBNER: I can’t keep my hands off the grasshoppers. They’re addictive. They’re like — they’re like cocktail peanuts.

ROZIN: You can buy these in stores, just dried grasshoppers. They won’t be seasoned this well.

SERMENO: I’m going to grab one too. 

ROZIN: They have good texture. Now, you have a little salt in there, right? What else?

SERMENO: Some chili and garlic.

ROZIN: You’re a creative chef.

SERMENO: Thank you.

DUBNER: So, do you personally feel it’s your mission to make insect eating more acceptable? Or you just happened to land here?

SERMENO: Yes. I do like grasshoppers. You go through Mexico’s streets and you can grab a pound of grasshoppers and eat it while you walk. It’s healthier than chips and stuff like that.

DUBNER: Is there any advice you could give generally on the idea of making insects more palatable to people? 

SERMENO: So, when they come for a first time, I try to give them the croquettes. It’s a little bit more soft. They’re delicious. They have cheese. A more similar taste. Then if they want to feel more adventurous, I will send like a whole dish of crickets or grasshoppers. I try to push it a little bit at a time. 

ROZIN: Our thing right now is black soldier flies. Black soldier fly larvae are the best because they are — it’s not that they taste better, but they live a short life cycle. They’re great for the future.

DUBNER: So, you’ll take the ants and the grasshoppers and the ant-flecked guacamole home? 

ROZIN: Oh, yeah. Yeah.

DUBNER: Thank you very much, it was a great meal. 

SERMENO: Oh, yeah, sure. Thank you. 

ROZIN: If I come back, I’ll bring you some black soldier flies. I have 10 pounds of them, because that’s the smallest amount I could get.

Most of this episode was produced before the pandemic shut things down. That meal I shared with Paul Rozin at The Black Ant was last February; as it turns out, it was one of the last normal restaurant meals I’d have — if, that is, a meal of ants and grasshoppers can be called normal. Maybe someday. I’m sorry to report that The Black Ant is closed — temporarily, for now. I’m even more sorry to report that Val Curtis, the British hygiene scholar we interviewed, died in October. She was 62; the cause was cancer. As you could hear from this episode, she was an incredibly energetic and optimistic researcher. She was trying to finish her latest book.

CURTIS: Well, yeah. I’m trying. I’m not getting enough time because I’m too busy building toilets.

A few months before she died, Curtis wrote an opinion piece in the Guardian. It was called “I’m One of the Thousands of Extra Cancer Deaths We’ll See This Year.” She linked her demise not just to the burdens that Covid-19 has put on the healthcare system, but to the austerity cuts made over the last decade or so to what she called “our brilliant National Health Service” in the U.K. “It took two months from my initial referral to the start of my radiotherapy treatment,” she wrote. After initial treatment, she was told she was in the clear; but there was a further occurrence. “It then took four weeks for an appointment to see a gastroenterologist and a further two to actually have the sigmoidoscopy and biopsy,” she wrote. “And then two more spent waiting for the results.” The pandemic, Val Curtis wrote, might cause an extra 35,000 cancer deaths in the U.K. alone. With that in mind, we’re turning our attention next week to cancer itself — cancer death, cancer research — and why so much of that research is in siloes where other researchers can’t use it, and what’s happening to change that. So, that’ll be our show next week. Until then, take care of yourself and, if you can, someone else too.

*      *      *

Freakonomics Radio is produced by Stitcher and Renbud Radio. This episode was produced by Matt Hickey with help from Daphne Chen. Our staff also includes Alison CraiglowGreg RippinMark McCluskyMary Diduch, Zack Lapinski, and Emma Tyrrell; we had help this week from Jasmin Klinger. Our theme song is “Mr. Fortune,” by the Hitchhikers; the rest of the music was composed by Luis Guerra. You can subscribe to Freakonomics Radio on Apple PodcastsStitcher, or wherever you get your podcasts.

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  • Paul Rozin, professor of psychology at the University of Pennsylvania.
  • Val Curtis, late disgustologist at the London School of Hygiene and Tropical Medicine.
  • Sandro Ambuehl, economist at the University of Zurich.
  • Emily Kimmins, senior manager of the sensory and consumer-science team for Kraft Heinz.
  • Iliana Sermen, chef at The Black Ant.


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