Introducing “Off Leash”

Stephen DUBNER: Alexandra Horowitz!

Alexandra HOROWITZ: Hi, Stephen. It’s nice to talk to you.

DUBNER: Nice to talk to you, too. Did you take your interesting vitamins this morning?

HOROWITZ: Yes. I’m ready.

Alexandra Horowitz is a writer and a cognitive scientist at Barnard College in New York, where she runs a dog cognition lab. She’s also the host of a new podcast. It’s called Off Leash, and it’s part of the Freakonomics Radio Network.

DUBNER: All right. I need you to fill in a couple of blanks for me. Dogs are to Alexandra Horowitz as blank are to blank?

HOROWITZ: What they are to me is like air is to mammals. They’re part of my existence.

DUBNER: Wow.

HOROWITZ: And intrinsic to it and necessary for it.

DUBNER: Without which you would die?

HOROWITZ: I don’t mean to be dramatic about it, but they’re part of me. Period.

DUBNER: Now it can’t be just a coincidence that dog is God backwards, can it?

HOROWITZ: I think you’ve got it mixed up. God is dog spelled backwards, obviously.

DUBNER: That makes a lot more sense.

HOROWITZ: Yeah, I knew you’d get it.

DUBNER: So, here’s the story the way I remember it. Maybe a year and a half ago, we had you on Freakonomics Radio in an episode of the Freakonomics Radio Book Club. And we talked about your first book, Inside of a Dog, which I had read years ago and loved, and then re-read it and loved it even more. By that time, I had gotten a dog. People loved that episode. And then we decided, “Hey, maybe we should make a whole show.” I’m curious if that jibes much, at all — zero? — with the way you remember it?

HOROWITZ: I think that is how I remember it. And I had thought of doing podcasts before, but it was only when you asked that, I thought, “Okay, maybe this is a possibility.” It reminds me of another thing I was just thinking about, which is sort of like, why would Freakonomics want to have Off Leash as a podcast? In my mind, “the hidden side of everything” could also be a catch phrase for how I look at dogs.

DUBNER: Yeah.

HOROWITZ: There are these ubiquitous phenomena, these familiar creatures all around us, and there’s just so much more to them if we just bothered to look.

DUBNER: Let me put you in the perhaps uncomfortable position of trying to persuade someone who doesn’t have a dog and thinks they couldn’t care less about dogs why they still might want to listen to Off Leash.

HOROWITZ: Well, that’s not uncomfortable for me. I’m interested in dogs for the dog’s sake, and I think there’s lots to be learned about them, but they’re also nonhuman animals. And as such, they serve as a way to reflect upon us human animals to notice ourselves and others and how we think about or treat others. The people I’m speaking to in Off Leash aren’t all dog experts. But we use dogs as a way to reflect on the experience of being human.

DUBNER: We are about to play for Freakonomics Radio listeners the first episode of your new show, Off Leash. This one is called “Smell.” Why is smell the first topic? What’s so central about that?

HOROWITZ: It’s the perfect first topic because I’m really interested in how the world looks to dogs, what it’s like to be a dog. And that’s going to start with their sense of smell, with how they perceive the world, which is nose-first.

DUBNER: After people hear this episode on smell and they fall in love with your show, they’ll go to their favorite podcast app and they will follow Off Leash. The third episode in the season is called “Property.” Tell us a little bit about that.

HOROWITZ: Most dogs are considered to be family members, but the law considers dogs to be things, property. In this episode, we really dive into that and talk about what it would mean for that status to change.

DUBNER: Right. The fifth episode is called “Strays.”

HOROWITZ: I love this episode. I think this is one which changed my thinking about dogs more than any other episode. This is about what researchers call free-ranging dogs, or we sometimes know as stray dogs, all those other dogs, 70 percent of the dogs in the world who do not live inside human homes.

DUBNER: Wow, 70 percent?

HOROWITZ: Yeah.

DUBNER: And when you say this episode changed your thinking about dogs, how so?

HOROWITZ: We always assume those of us who live with dogs, that dogs have a terrific life. But if 70 percent of dogs are stray, we start to look at their lives. Are their lives really so bad? They have a lot of freedoms that our dogs don’t have. It just is another way to reflect on the nature of what the best thing is for dogs.

DUBNER: I have to say I’ve learned so much about dogs, especially my dog, from just hanging out with you and talking with you. So, thanks for that.

HOROWITZ: You’re welcome.

DUBNER: And congratulations on Off Leash. Personally, I think it’s turned out amazingly well. I hope people not only do love it, but I really hope they’ll tell their friends and family to listen to it. This episode you’re about to hear is called “Smell.” Its host is Alexandra Horowitz, who I’ve been speaking with. And it sounds like this.

*      *      *

Imagine your first cup of coffee of the day. It smells terrific. You bring it up to your lips and you notice something: it’s sweeter. Maybe someone has put a teaspoon of sugar in your black coffee by mistake? We might notice it by taste, not by smell. But a dog — a dog’s nose would notice it. In fact, a dog’s nose could detect that teaspoon of sugar if it had been added to a million gallons of water. That’s two Olympic-sized swimming pools’ full.

Dogs are creatures of the nose. In their noses, they have hundreds of millions more olfactory cells than we do in ours — and those are the cells that translate a molecule into the experience of a smell.

Welcome to Off Leash. I’m Alexandra Horowitz.

This is the podcast where we explore the relationship between humans and dogs — I’ll invite an interesting person and their dog to join me for a walk, and then, we’ll see where the walk takes us.

Tejal RAO: Okay, we’ve somehow ended up at a dumpster in a parking lot.

As a researcher of dog cognition, I’ve studied what dogs can perceive with their noses. As a writer and person who lives with dogs, I’m always thinking about how dogs smell their way through their world. Today, we’ll talk to a detection-dog handler about what her dogs are trained to sniff out for her.

Julianne UBIGAU: Our freezer is just a beautiful library of scat.

But first, I take a walk with a restaurant critic and her dog Lulu, and discuss the role smell plays in both of their daily lives.

RAO: She’ll never forget that she smelled a rotisserie chicken there once.

And we’ll put our own noses to the test:

DUBNER: Whoa. I think I know what motor oil smells like now.

Ready to go for a walk?

*      *      *

RAO: Here, Lu. Have a drink. Have a drink.

That’s Tejal Rao with her two-year-old pit bull mix, Lulu. Tejal is the California restaurant critic for The New York Times. She and Lulu are walking down a busy street in Los Angeles.

RAO: I’m on Figueroa street in Highland Park in Northeast Los Angeles. There’s a mix of barbershops, guys selling cold coconuts on the street and cut fruit, fancy grocery stores selling natural wine, chain bakeries. It’s just a — Come on, mama. It’s a big mix.

HOROWITZ: What does it smell like?

RAO: Right now, I smell gasoline, yeast, roasted coffee, trash. What about you? Where are you?

HOROWITZ: I am in Riverside Park in New York City, where the sun is just setting, and the purples and oranges are bleeding into each other. But there’s a highway proximate to me. You might hear that. And there is a little bit of petroleum in the air, and the overarching scent of New York dust.

RAO: So, we’re passing an open pizza box with a slice of pepperoni on it in a parking lot, but I guess she doesn’t have a taste for pepperoni pizza. It’s funny because the things I see that I think are going to attract her don’t, and then she’s drawn to an invisible world that I can’t access.

I wanted to walk with Tejal because she’s a writer on food and a restaurant critic, so she is especially attuned, in a way many of us are not, to her sense of smell. Of course, the same could be said of her dog Lulu, or her other dog, Kimchi.

RAO: I thought about bringing her along today, but she’s 12 and she likes her afternoon naps. So I left her at home. But she’s always had this really amazing ability. If we’re at a park and a tennis ball has gotten hidden under a bench — or even a single piece of miniature kibble — she will find it. And there have been times where she’s kind of digging up the rug or trying to get under the couch and I’m insisting there’s nothing there. I’ve gotten on my hands and knees, and I’ve checked and there is definitely nothing there. And then I get really frustrated and move the couch, and she is completely right. There’s a single piece of kibble, wedged between the rug and the wall and she absolutely knew it. I think she would have made a wonderful police dog in another life.

As someone who thinks about food professionally, Tejal was already keen on noticing smells. Back in October 2020, she published a piece in The New York Times called “Building a Personal Smell Museum of Los Angeles,” in which she “collected” smells meaningful to her in her neighborhood — her neighbor frying onions, smoke from wildfires, and the “tarry scent” of road work. But shortly after the piece ran, everything changed.

RAO: So, a few months after I put together that museum of smells, I got Covid and lost my sense of smell. I realized when I didn’t have my sense of smell, how much I needed it for just the most basic things, like frying garlic. There are all these little different moments before it’s burnt, where you can stop it for different flavors. And I would miss them all. At the same time, because I didn’t have my sense of smell when I was eating for those couple of months, I didn’t really know exactly what I’d gotten wrong. Except for extremes. I maybe knew if I had burnt something, but all the sort of subtleties — everything in between — was lost.

HOROWITZ: I sometimes feel like that is a way to describe the difference between the human’s and the dog’s sense of smell, like that we notice the real extremes.

RAO: Yup.

HOROWITZ: But not the middle. And maybe dogs are noticing the range of the middle.

RAO: And that range is so wide. That range is enormous.

Losing one’s sense of smell, even if you’re not working with food in your profession, can be depressing and disorienting. It’s when we notice how much we rely on ordinary smells in daily life: the regular smell of your house or car. The familiar smells of people you know or places you go. And because so much of taste is based on smell, foods are reduced to sweet, salty, sour, and just some texture in the mouth. For a person who writes about food, that is devastating. So, like many people who lose their sense of smell, Tejal tried something called “smell training” to try to re-awaken her nose. It’s a practice of daily repetitive sniffing of a few distinct odors. And after three weeks, her sense of smell returned.

RAO: The very first thing I smelled again was horrible. The smell of soured milk in the fridge. I opened a liter of milk and it just rushed out. And it was a reminder that my sense of smell is — in addition to being about pleasure and joy — warning me all the time about things that are dangerous.

HOROWITZ: Did having that experience of the simultaneous feeling of disgust of the smell, but also the pleasure that’s realizing that your smell had returned — has that changed how you feel about some of those disgusting smells?

RAO: Yeah, I’m just so grateful for all of it. When I was in the process of getting my sense of smell back, I would go outside when the garbage truck came down the street. I would just try and get as much information as I possibly could. I would drive with the windows open and each dog would be at one of the open windows and I would be trying to do that, too, trying to see what little fragments I could pick up in the air.

HOROWITZ: In some way, having your sense of smell leave and return might’ve made you closer to your dogs. Or made you, maybe, appreciate their ability a little bit more.

RAO: Yeah, I think so. The other day we were walking in the park and Lulu found a whole rotisserie chicken under a bush — like, a jackpot. And every single day since then, she remembers. The chicken is long gone, but it’s like she has this map of smells.

HOROWITZ: Right.

RAO: She knows our space so well by all the smells. And she’ll never forget that she smelled a rotisserie chicken there once.

HOROWITZ: Your smell museum idea is like her making a smell map of the street and knowing: “That’s where the chicken was. This is where the bagel rolled under the bench.” And maybe there is a little rotisserie smell remnant in the air.

RAO: I always think about how she likes to stick her head out the window and just let the breeze hit her, and her ears are flapping in the wind and her tongue is hanging out. And you can see that she’s reading things so quickly. Like, she’s getting so much information in just a second or two. And I wonder what it is that she’s catching, but I don’t know. And when I have been at a friend’s house and come home, I know that she understands I was just with two different cats, and three different humans, and we ate a lasagna.

In my own research on dogs’ perception, I’ve confirmed that they do recognize their people by smell — and they can smell where you’ve been and who you’ve been with. Dogs know their own smell, and their friends’ smell, and they notice if the smell has changed — like looking in the mirror and noticing a new gray hair. And dogs do have a kind of “smell map,” so they’re able to navigate by smell. As a result, their noses are brilliant at helping us humans locate things that we can’t find on our own. You may have heard of drug- or explosive-detection dogs, bedbug-detection dogs, search-and-rescue dogs. But did you know that there are dogs who can detect when a cow is in heat? Who can sniff out counterfeit goods? Researchers are training dogs to detect cancer — and, of course, recently, lots of programs are training dogs to smell Covid But the happiest detection dogs might be the ones who work with Julianne Ubigau.

UBIGAU: I am a researcher at the University of Washington’s Conservation Canine program.

This canine program uses their noses to do a kind of wildlife “forensics” — finding traces of wild animal populations that researchers want to study but are too elusive, or just too hard to locate. The traces they are trained to sniff out? Wildlife “scat.”

UBIGAU: It’s wildlife poop. It’s the waste products of animals that actually has a lot of value. The center specializes in extracting D.N.A. and hormone information from organic materials in order to learn more about endangered wildlife.

HOROWITZ: I’m imagining people listening to this and thinking, “Okay, so these dogs are sent out to find poop, basically. I have a dog who is always finding and consuming poop.” And they might be thinking, “Wow, this is the life, right? This must be the most fun thing ever. And maybe my dog could be a detection dog.”

UBIGAU: I used to say that most dogs can’t do this work, because you have to have a dog that, if given the opportunity to go get a ball that’s laying on the floor or grab a piece of steak, we want the dog that goes for the ball and ignores the steak.

HOROWITZ: One thing I love about Conservation Canines is that they’re all rescue dogs. I’ve heard you say that you work with dogs who are called “unadoptable.” Can you explain what you mean?

UBIGAU: While many working dogs are bred to be a working dog, we’re looking for dogs that have the right personality. And when visiting shelters, you see what dogs do not get adopted out. And they’re the ones that are “crazy” or “too much energy” — just not suitable for the home. That works really well for us, because we want a dog that has lots of energy.

From the scat the dogs locate, the researchers back in the lab can figure out who the animals are, where they are, and what kind of shape they’re in.

UBIGAU: We can get hormone measurements, which help us determine how stressed or healthy or pregnant an animal is. We can also get a lot of D.N.A. information that gives us population estimates on a species in the area. We can also get the D.N.A. of the prey that the animal ate. And here, the animal doesn’t even know that we were out there, most of the time. We can find scat that was pooped five minutes earlier. But we can also find scat that’s been there for more than a year.

HOROWITZ: I have a long list of animals that the dogs have been trained on. And I want you to fill in any who I’ve missed. I have: short-tailed weasels, cougars, saw whet owls, tigers, lynx, wild boar, European badgers, pine martins, grizzly bear, wolf, coyote, lion, cheetah, wild dog, hyena, bats, pocket mice, salamander, fisher, wolverine, mink, the silver spot caterpillar — whose scat is called “frass.”

UBIGAU: Yes.

HOROWITZ: Did I miss any?

UBIGAU: Oh, swift fox. The feathers of goshawk, and the pellets of a goshawk. And then the egg masses of the American bullfrog. We have quite the freezer. Our freezer is just a beautiful library of scat from studies going back 20 years, now.

It also has whale scat. Julianne’s first job as a handler was working with Tucker, an Orca scat detection dog.

UBIGAU: Orca Detection Dog Tucker. Yes.

HOROWITZ: Tell us a little bit about how orca scat works. I mean, you’ve got these killer whales pooping in the sea.

UBIGAU: Yeah.

HOROWITZ: How is the dog supposed to detect that?

UBIGAU: The scat of this whale — it looks like snot, smells like salmon, and it has enough fat content that it floats on the water for a short period of time. So, the fact it floats is our window of opportunity as scientists to get in there and get a scat sample. So, Tucker is our secret weapon. He helped us figure out that we could collect scat samples from these whales at a safe distance — meaning we’re not trying to interfere with the feeding habits of the whales. We’re not driving our boat right into the pod. So, it’s a really great non-invasive way of collecting information on these whales.

HOROWITZ: He could detect scat a nautical mile away, which seemed extraordinarily impressive for something that was just momentarily on the surface of the sea.

UBIGAU: It didn’t make sense to us, because it seemed like, “Oh, he must’ve been alerting to something else.” But no, it was just that he was alerting to it much further away than we thought possible. Tucker rides on the bow of a small boat and he looks very stoic. It’s the handler’s job and the boat driver’s job to just watch. His little nostrils would be twitching from side to side. And when the wind blew and carried the odor of the scat on it, he would just snap into action. So, watching Tucker work on the boat, he can’t run. And we actually selected him as a really great whale dog because he is a lab that doesn’t like to swim.

HOROWITZ: So he won’t jump in?

UBIGAU: So he won’t jump in. So, Tucker stays on the boat, and it’s Tucker’s job to go from one side of the boat to the other. And he’s basically telling everyone, like, “The odor is upwind now.” And then, once he would move his head the other direction, the boat driver would know that we’ve passed the scent cone and we need to go back. It’s amazing, because if he had a voice, he’d be going, “Go right. Go left. Go right.” He doesn’t. He’s just turning his head and the dog handler is then communicating, “Go right. Go left. Go right. Go straight.” So the boat is doing this zig-zaggy pattern. And when the boat is going right into the source of that target odor, Tucker’s right on the bow of the boat.

HOROWITZ: That’s great.

UBIGAU: It’s beautiful.

The more people hear about it, the more they are convinced that dogs’ ability is sui generis — completely unlike what we can smell. That may be true, but our noses are perfectly good instruments themselves — if we just bother to sniff. After the break, we’ll hear more from Julianne about what the Conservation Canine dogs have found for her. And I’ll do some smelling of my own — with a few friends.

DUBNER: Read these instructions carefully before beginning, it says.

Angela DUCKWORTH: I’m not going to read the instructions carefully, but I get the gist.

So, stay with us. Stay…  

*      *      *

Welcome back to Off Leash. I’m Alexandra Horowitz. And today, we’re following dogs into the world of smell. We’ve been speaking with Julianne Ubigau, who works alongside detection dogs who wield their noses in search of endangered wildlife scat. Julianne has worked with these dogs for the last 16 years. After all this time, I wondered what she thought the world looked like to them with smell as their dominant sense.

UBIGAU: That is a really beautiful question. You know the bioluminescence that, if you stir up the water, you can see? That’s the vision I get in my head.

HOROWITZ: Right. If anyone’s ever been out when there’s bioluminescence in the sea, on the waves — especially when they’re crashing — are just entirely lit up with all these little creatures.

UBAGAU: It’s magical.

HOROWITZ: Yeah. It is magical. And I wonder if dogs view that as magical — if that is, in fact, how they see it, or if it’s just the way the world is. It’s just the way the visual world is laid out in front of us.

UBIGAU: They are so patient with me, because I am so dumb when it comes to this.

HOROWITZ: We’re all dumb when it comes to smell.

UBIGAU: It’s like there is an electromagnetic spectrum where we can see just this tiny, tiny sliver as visible color and light.

At the same time, if we follow the dog, sometimes we can see what they can smell.

UBIGAU: Just the other day, we’d finished a carnivore research project, and we’re walking on the road. And I’m always just kind of watching. When he’s going down a road, and he stops and he sniffs something, and I can tell: I’m like, “Oh, he’s canine-ing.” He’s sniffing something that marked the side of the road. I’m not looking to collect that information, but it is interesting to me, because it’s like I get to see the activity that’s happened in this area through his senses. If I’m willing and patient enough to slow down and watch that, it’s like I’m piggybacking on his superpower. I can imagine that a coyote just walked down this road. In this particular case, the next morning there was a light dusting of snow. And what I had watched him do the day before, I could now see the evidence — the tracks. He didn’t need that light dusting of snow to see that there were three coyotes that just went through this area — he sees that all the time. But I, because of the snow, was able to get a glimpse of what he was smelling.

HOROWITZ:  I love the idea of snow as a kind of filter that lets us see a little bit more of what they’re seeing all the time.

UBIGAU: Yes.

HOROWITZ: Someone who’s been here, someone who’s left that, and is no longer there, which feels miraculous to me — smelling through time.

UBIGAU: It’s like you get to see the ghosts of everything that happened here.

In recent years, the Conservation Canine program has also started doing detection work separate from animal scat. Julianne and her partner, Jasper — a big, jovial black lab — work to find P.C.B.s — that’s the shorthand for the harmful chemicals, polychlorinated biphenyls. One thing about P.C.B.s: They’ve always been known to be odorless. But Jasper has proven he can smell it. And what’s incredible is that, by following Jasper as he showed her where the P.C.B.s were, Julianne found that she, too, suddenly, could smell this “odorless” substance.

UBIGAU: What we’re learning as humans, as we watch the dog detecting this window sill, or this building, or this paint, is: While their sense of smell is way better, many times we can actually smell P.C.B.s.

HOROWITZ: What does it smell like?

UBIGAU: It smells like sweet chlorine. Sometimes it is so strong that I feel like I get a headache. Most people don’t even notice that it exists, but once you notice, then you’re like, “Whoa.” So the dog is helping us learn that we can smell something we thought was undetectable. It’s pretty neat.

Another way we might appreciate dogs’ sense of smell is to bother to notice what we humans know — or don’t know — about the way the world smells. So I recruited my fellow Freakonomics Radio Network hosts Angela Duckworth and Stephen Dubner to do a little smelling experiment with me. They co-host the podcast No Stupid Questions. We sat down with three copies of the University of Pennsylvania Smell Identification Test, which is a scratch-and-sniff test of olfactory function. It’s typically used by researchers to determine whether someone has anosmia — that’s a loss of a sense of smell. But for our purposes, I wanted to see how dog-like we were: Could we identify these odors out of context?

DUBNER: Read these instructions carefully before beginning, it says.

DUCKWORTH: I’m not going to read the instructions carefully, but I get the gist.

DUBNER: Okay. Page one. This odor smells most like a) gasoline, b) pizza, c) peanuts, or d) lilac.

HOROWITZ: That makes it so much easier, having options.

DUBNER: It’s not gasoline. Not pizza. Not peanuts. It doesn’t smell like lilac, either. But I’ll say lilac because it definitely smells more like something that grows out of the ground than gasoline or pizza. 

DUCKWORTH: Since I didn’t like the way it smelled, I’m just going to say gasoline. 

DUBNER: I wish my dog was here. I think she could sort it out.

DUCKWORTH: I have a confidence of nine out of 10 that it’s gasoline.

HOROWITZ: It’s definitely pizza.

DUCKWORTH: What?! No.

HOROWITZ: Here’s what I think. It’s a bad, day-old pizza. And it’s not the whole pizza. It’s the crust and the seasonings, and a little bit of that deep tomato-pastey smell.

DUBNER: Can I just say? I’m really glad your profession is “cognitive scientist who specializes in dogs” and not “pizzeria owner.” Because if your pizza smelled like this, I don’t think you’d be doing that well. No. 5. This odor smells most like: grass, pizza, motor oil — I didn’t know motor oil smelled like anything — or pineapple.

HOROWITZ: Oh, this one’s actually confusing.

DUBNER: Whoa. I think I know what motor oil smells like now.

DUCKWORTH: There is something so horrible about this smell.

HOROWITZ: It’s like a childhood smell. But I can’t place it. Can you picture something?

DUBNER: I did have a sort of Proustian rush where I couldn’t identify it for a while. And then I got a sort of image of some man that I couldn’t identify, that was maybe a friend’s father in a garage.

DUCKWORTH: Working on a car!

DUBNER: “Is that you, Uncle Pete?”

DUCKWORTH: I was going to say Pep Boys. Manny, Moe, and Jack.

DUBNER: There you go.

DUCKWORTH: I’m 11 out of 10 on confidence on this one. Seriously, I’m going to redeem myself from the pizza one.

DUBNER: Alex, what’d you write down?

HOROWITZ: I wrote motor oil.

DUBNER: So we all wrote motor oil.

More than seeing who’s the “best” smeller among us, what I love about smell-guessing games like this is hearing everyone’s process of searching for smells in their minds. It gives us a little access to the experience of olfactory perception that we don’t have a window to with dogs: What does this odor smell like? Or remind us of? Or make us feel like? Every time I talk to people about smell I hear the same refrain: “I’m not good at smelling.” But then if I ask them to think back to a memory from childhood involving smell —

DUCKWORTH: Easily. So many. My mom making sesame noodles with sesame oil. The Pep Boys — like, hanging around with my dad on Saturdays while he looked at tires, that smell of rubber and also the motor oil and gasoline.

HOROWITZ: Stephen?

DUBNER: Oh, yeah. My childhood was very smelly. We were kind of a farm family, so there were animal smells. The chicken shit was really pungent. We had a lot of dogs and cats, and each of them had their own smells. And I used to burrow my face in the dogs’ coats all the time. So, I knew all their smells very closely. And then we had these neighbors, this elderly couple who lived up the hill. They had an orchard, and their kitchen smelled like all the best fruits in the world. I would say that probably five times a day today, still, I smell something that makes me think of my youth. It’s a very strong connection, I guess. But almost an emotion, because it triggers memory in a very, very deep — an instant way.

HOROWITZ: It’s definitely the case that it’s the quickest route to the brain. The olfactory bulb is right behind the nose. And it might be a little bit unmediated by language, so it gets processed more quickly. And I think these types of reports that we’re talking about are a testament to the fact that most of our smell memories are positive emotional smell memories. Rarely does somebody tell me if I asked them about an early smell memory, some horrible smell memory where something devastating happened. Many of them have this positive valence, even if the smell was chicken shit. So I wonder, for dogs, I think that their perceptual and therefore cognitive life is probably not full of these same kind of deeply emotive recollections, because I think for them smell is just the way the world looks.

DUBNER: Really?

DUCKWORTH: Maybe it’s like vision.

HOROWITZ: Yeah.

DUCKWORTH: I feel like when I see dogs and they’re like sniffing everywhere, it’s like they’re feeling around, trying to figure out what’s going on in the world.

To dogs, odors are neither good nor bad; they’re just information — about what and who are present, about who’s been here before, and even about who’s coming around the corner. For us, for the most part, smells are much less a part of our sense of the present moment — but they do bring us, sometimes, back to past moments. Vividly. I asked Tejal Rao, the restaurant critic who we spoke to earlier, about her earliest scent memories. Raised by a mother from Uganda and a father from India, she spent her childhood in Kuwait; Sudan; rural France; and Atlanta, Georgia — influences which came up while walking with her dog Lulu.

RAO: Oh, there’s so many. The first thing that just came to mind was the smell of my grandmother’s closet when I was growing up. She had this amazing collection of saris — the several-feet-long pieces of silk and cotton. And they were all ironed and folded, so the closet always smelled like those materials. Not musty, exactly, but with a mix of her perfumes and the clean laundry smell. That’s a very comforting smell to me that I haven’t smelled in 20 years or something, but I can call it back.

HOROWITZ: You can imagine the smell?

RAO: Yeah, absolutely.

HOROWITZ: Oh, I think that’s a little bit of a superpower, yourself.

RAO: When I was getting back my sense of smell, it’s true that I was accessing memories that I didn’t have access to when I didn’t have my sense of smell. I started smelling certain spices every day. And when I was chewing on some cardamom and trying to inhale the aroma, I was reminded of my grandfather, because he used to always smell like cardamom because he would chew on it. But I wasn’t just reminded of him. It was like little tiny memories opened up that I’d forgotten — very vivid images. And I wonder if I hadn’t got my sense of smell back, if those images would have just been lost.

HOROWITZ: Were there certain smells you were longing to experience?

RAO: Oh gosh. The thing I missed the most is so gross that I’m a little embarrassed to share it. But I actually really missed the smell of my other dog’s fishy breath, which smells like anchovies or something. Really awful. She would yawn, and there would be nothing. And I would feel really sad.

HOROWITZ: Right.

RAO: Even though it wasn’t a particularly pleasant smell, there was something about its absence that made me feel isolated from her. I should add that I also missed the smell of my husband’s hair and skin. It wasn’t just my dog’s nasty breath. I’m not a monster.

Thank you, dogs, for showing us this world that humans have stood up from and forgotten. Thanks to Julianne Ubigau, Tejal Rao, her dog Lulu, my friends Stephen Dubner and Angela Duckworth — and to you for coming on this walk with us.

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Freakonomics Radio is produced by Stitcher and Renbud Radio. This episode was produced by Molly Getman and Lyric Bowditch. Our staff also includes Neal Carruth, Gabriel Roth, Greg Rippin, Ryan Kelley, Zack Lapinski, Rebecca Lee Douglas, Julie Kanfer, Morgan Levey, Eleanor Osborne, Jasmin Klinger, Emma Tyrrell, Lyric Bowditch, Jacob Clemente, and Alina Kulman; we had help this week from Jared Hohlt, Jeremy Johnston, and Alison Craiglow. Our theme song is “Mr. Fortune,” by the Hitchhikers; the rest of the music this week was composed by Luis Guerra. You can follow Freakonomics Radio on Apple Podcasts, Spotify, Stitcher, or wherever you get your podcasts.