The days I'm not on TV in the early morning, all start off pretty similarly. I get up slowly, read my email, watch something on YouTube, and eventually I'll find my way into the shower. Now, I don't know about you, but when I'm in the shower I think about a lot of stuff. One thing I thought about recently, funnily enough, was showers. Specifically, how often I take them. I'm firmly in the camp of people who shower every day. And according to the pollster YouGov, that's easily the majority here in America. Roughly two thirds of a shower or bathe at least once a day. And if you're on team shower, you probably passed some judgment last summer when you heard about Mila Kunis and Ashton Kutcher's approach to their kids hygiene.

Just weeks after the couple sparked a debate over celebrity bathing habits when they revealed they only bathe their kiddos when they're, quote, visibly dirty.

I will admit that despite my appreciation for a hot shower, my initial reaction to this controversy was a big ball of "what is going on here?" But then I took a step back. According to Gallup, in 1950, fewer than 30% of Americans took a shower or bath at least once a day in the winter. But now roughly two thirds of Americans shower or bathe daily. So I decided to dig into the issue a little more. Why are we bathing so much now and do we actually need to? Where do we draw the line between what's necessary for our hygiene and what you just marketing? Well, today I'm going to find out. And if I have to become a human guinea pig to do so, then so be it. I'm Harry Enten, and this is Margins of Error.

The most important thing, of course, is a daily bath in summer. Or in winter when you're less hot and sweaty, every other day will do. Make it a shower or a tub. Whichever you like. Morning or night. It doesn't matter. Just so you keep yourself clean.

This is from a 1950s educational video designed to teach eighth graders proper hygiene. But the advice hasn't really changed since then, right? It's all about keeping yourself clean. And we Americans love keeping ourselves clean. We're obsessed with it. In this country, health and beauty products comprise a multibillion dollar industry. But to understand our current obsession with being clean, we have to talk about where this impulse came from and the history of hygiene. It's a little more complicated than you might think.

People were extraordinarily clean, followed by centuries in which people were extraordinarily dirty.

This is Katherine Ashenburg, author of the book "The Dirt on Clean: An Unsanitized History." If you want to understand America's current fascination with cleanliness, Katherine says, all roads lead to Rome.

The ancient Romans' colossal imperial baths in which they poured unbelievable amounts of resources as well as technology. These places, which were stunning, they were art galleries and sculpture galleries and gardens. And you could do all kinds of things in waters of different temperatures. People think that the average Roman man could spend up to 3 hours a day in one of these imperial baths. And baths were so important to the Romans that there's a famous letter in which some Roman official writes to the governor of this filthy cold, in their mind, savage country of England, which was just about to become part of the Roman Empire. And he says to the new governor, "to bring these people up to Roman standards, three things are necessary. They have to learn how to wear togas. They have to learn Latin. And they have to learn how to take our kind of baths." That's how important baths were for the Romans.

However, after the Roman Empire fell, most of its baths fell into disrepair and Western hygiene took a step back. Around the same time, Christianity was becoming more and more popular. And as a religion, its approach to hygiene was rather hands off.

Christianity is probably the only world religion that has no interest in cleanliness for its religious meaning. And as a matter of fact, they thought that the dirtier you were and the stinkier you were, the holier you were. So what brought those steam baths back into Europe was the Crusades. So crusaders found people there bathing in what was really the only remnant of the Roman bath. Not a great big, amazing imperial baths, but people were getting marginally cleaner by the time that the Black Death intervened.

I'm sure I don't really need to explain the Black Death to you, but let's just cover the basics. A plague struck Europe in the late 1340s, and within a few years, somewhere between one in every three and one in every two Europeans died.

And needless to say, Europeans were terrified. The king of France asked the professors of medicine at the Sorbonne in Paris what what caused this? And what can we do to prevent it? And the thing that influenced cultural life and social life for centuries to come was the learned doctor's belief that you would be more likely to get the plague if you took warm baths because they said warm baths will open your pores and the disease will enter through the pores. So this completely wrongheaded idea resulted in what a French historian named Jules Michelet called "a thousand years without a bath." Actually, it was probably closer to 500 years without a bath, depending on your country and your class. But people were terrified of getting into warm water, much less hot water, for example, 17th century, Louis, XIV, the king of France, lived a very long life. He was a very athletic guy, and he took two baths in his entire long life.

Did you catch that? Louis XIV lived for almost 77 years, and he took two baths in his whole life.

But Louis XIV, was considered very, very clean because he changed his white linen shirt three times a day. And this was the really weirdest thing of all about the 17th century. They believed that if you put on a white shirt, the flax in the linen would draw out dirt from your body, which I don't think that's really true. But anyway, Louis XIV passed for a very fastidious guy.

So within just a couple hundred years, how did we go from the flax in your linen will draw dirt from your body, to being obsessed with being clean.

You can see signs of it, first, in the 18th century. The signs depended on the country you lived in and your class. But broadly speaking, people were beginning for the first time not to enjoy the smell of sweat, either your own sweat or other people's sweat. But it took a very long time. And it really wasn't until I think it's the 1860s that a doctor actually wrote a book called "Baths and How to Take Them," because the taking of a bath was such a lost art that people had to be instructed how to do it.

At the same time, people were seeing first hand the positive effects of our growing understanding of germ theory. And much of it happened during the American Civil War.

People in charge of the Union Army created a thing called the Sanitary Commission, which at first was very much laughed at. It was inspired by Florence Nightingale, who had found in the Crimean War that deaths, not through being shot, but deaths from being a soldier in a war could be cut enormously if you gave soldiers soap and water and a pail and they washed themselves and cleaned their sheets and they were much less likely to get infected and to die of of an infection.

So after the Civil War, two things became a much larger part of everyday life in America. The first: affordable soap that wouldn't hurt your skin if you used it frequently.

They didn't have what we call toilet soap. They had soap in which they washed their clothes, in which they washed their floors. But it was very harsh and it was also very soft. So it took a long time for people to develop an affordable toilet soap, a soap in which you could wash your body. That was hard, that wouldn't turn into some disgusting, mushy mess, and that would not hurt your skin.

Humans had been making soap for thousands of years, but in America, it wasn't until the 19th century that store bought soap started becoming more common, though for most people, it remained a luxury item for many years. Which brings us to the second thing that became a much larger part of everyday life here after the Civil War.

At the same time, a new thing under the sun in a large scale way was born. And that was advertising. Advertising and soap kind of grew up together and supported each other, I would say. Other than patent medicine, the selling of soap was the outstanding success of the early years of advertising. And they found Americans a really, really susceptible public for their messages. So that would be like pictures of apparently lovely young women. And the tagline would be "always a bridesmaid, never a bride." Why? Because she didn't use Ivory Soap or Colgate Palmolive or whatever it was to clean her body and she could, very important word in soap advertising, she could "offend" without even realizing it herself.

So since store bought soap was still a luxury item for many people, and if you look at the polling on bathing, even to this day, you'll see clear divides based on socioeconomic lines, advertisers had to convince Americans to spend their hard earned money on soap. So, soap became aspirational. If you wanted to climb the ladder, pull yourself up by your bootstraps and all you needed to smell good. And so you needed to buy soap. But soap advertisers didn't just settle with trying to make you feel inadequate. No, no. They also latched on to the public's growing trust in germ theory.

Somewhere around the cusp of the beginning of the 20th century and moving into about 1920, people really began to understand that it was, not just it would prevent you from getting married or getting promoted, but that it was actually physically dangerous to be unclean. So that was really, I won't say a feather in advertising's cap because it was serious, but it really coordinated very well with what they wanted to do.

Of course, buying and actually using soap was predicated on access to baths. And as you might have guessed by now, the history of indoor plumbing in private bathrooms in America is complicated. But here's the short version. In the late 1890s, only the very wealthy had bathrooms in their homes for the rest of society. You could either do what you'd always done, store water in buckets and take a sponge bath every once in a while. Or you could go to the public bathhouses. But bath houses weren't a hit here in the United States. There were upscale ones for the well-off, even though many of them already had their own bath or shower. And the public bathhouses for the lower class? Well, there weren't that many of them. They were cheap and they signified poverty. So at the time, the people who had baths and showers of their own were much more likely to pay than those who didn't. So just like buying soap at the store, owning your own bath or shower became an aspirational part of American society. And within a short amount of time, things had changed pretty dramatically. By the mid 1930s, 89% of apartments in New York City had baths or showers. And by 1940, 55% of all American houses had a complete bathroom. And this is where our present day obsession with cleanliness was born. Americans were being told constantly that they were too smelly, too sweaty, too dirty, and also that without hygiene products and without their own private baths or showers, they were being unhealthy. Soap and deodorant weren't only necessary for survival. Without them, you'd be a stinky loser. A real one two punch for the ages. But towards the end of the 20th century, things started changing again with something Katherine refers to as the hygiene hypothesis.

This had a big groundswell in 1989 when the Berlin Wall fell and a scientist whose name was Dr. Erika Mutius. She was investigating this kind of troubling rise in allergies and asthma attacks among, especially children. She was from West Berlin and she said, so I have the clean, sophisticated, affluent West Berlin children and I have the poor, polluted, unenlightened children of East Berlin and but they're from the same genetic background, etc.. So this is a beautiful way that I can do my experiments.

Dr. Mutius expected, like many of us might, that the clean children from the more affluent West Berlin would have fewer instances of allergy and asthma.

But to her amazement, she found absolutely the opposite. The clean, unpolluted, prosperous children of West Berlin had all the allergies and asthma that people were beginning to worry about. And the poor kids in East Berlin in their polluted apartments did not. So the hypothesis was that we're making our houses and our bodies to clean, and we're not giving our immune system anything to kind of exercise their muscles on. That is a fascinating kind of scientific bulwark towards people who are now trying to tell us that our over cleanliness is actually dangerous for our health.

These findings set off a shock wave in the scientific community, which has led to decades of studies and research over this very question. Have we gotten too clean? After the break, I'll talk with a doctor who's got bad news for germaphobe. Our bodies are covered in germs, and that's a good thing.

Hey, folks, welcome back. So before the break, we were talking about the hygiene hypothesis, which suggested that our overzealous pursuit of cleanliness was actually leading to a rise in conditions like asthma and allergies. Now, it's easy to hear that and nod along. But does that mean we should actually be dirtier? And how did you respond when I said that? That you should be dirtier. If that thought made you shudder a bit. Well, you're probably not alone.

There's some things that are genuinely, like, really offensive, viscerally nauseating to people about certain human smells. But there's a lot of it that's just kind of we're not used to smelling anything at all. And if you ever smell anything from a person that is we say gross or disgusting or whatever.

This is Dr. James Hamblin. He's a specialist in preventive medicine, a lecturer at Yale, and the author of the book "Clean: the New Science of Skin and the Beauty of Doing Less." He made headlines a few years back when he decided to stop showering cold turkey.

Hygiene practices are one of the last areas where people will openly call one another gross or disgusting, whatever, like. We've made a lot of progress in a lot of other areas, but that is still just the area of just like, unrepentant judgment. And we need to examine that.

This unrepentant judgment has been with us for a while, like take Pig Pen, the Charlie Brown character.

Frieda: You're an absolute mess. Just look at yourself. Pig Pen: On the contrary, I didn't think I looked that good.

People love making a stink about other people's personal hygiene. And James, well, he experienced that kind of judgment firsthand after he revealed that he'd stopped showering.

You know, the things people said about me publicly, it's so embarrassing once, you know. Like to call someone gross or disgusting in the way we, you know, in previous eras would have with things like, I don't know, obesity or different, you know, nontraditional sexualities. I think, you know, people would just pass that sort of judgment and think, oh, of course, well, everyone thinks that and this is abnormal. Right? And it's not like people actually smelled me. They just heard that I stopped showering for a while and already I was gross. I'm disgusting.

Part of the problem, according to James, is that we've conflated hygiene with cleanliness. So I asked him to explain the crucial difference between the two.

Hygiene is a term in public health for practices that are meant to prevent disease. So that's pretty straightforward. It's mostly that you don't want to be transmitting bodily fluids and sharing contaminated air with other people. So that means saliva, blood, mucus, vomit. Basically, anything that comes out of you, you want to make sure that that's cleaned off and that you are not transmitting disease. Whereas cleanliness is much more socially constructed and determined and involves things like Do you smell offensive to people? Is your hair, you know, nicely combed or does your skin look oily? It's much more judgmental.

So I guess my big question would be, why is this distinction between hygiene and cleanliness important to make?

Oh, well, for a million reasons, because I think because of marketing, the two ideas are tied up alongside one another, like the idea that you have to wash your face in order to be clean or shampoo every day or, you know, scrub your shoulders or else you're not clean. But I think a lot of people are doing it under the idea that there's some health aspect to it that they need to do it. And that is, yeah, the results of marketing.

Now, over the years, scientists have spent a lot of time looking at what makes our skin tick. One area of growing interest the germs or microbes living all over our skin which make up our skin's microbiome.

The microbiome is usually more casually defined as just like the microorganisms that live on and in us. Typically people talk about the gut microbiome because that is the largest collection of microbes that we carry around. But we also have microbes all over our skin, especially in the more oil heavy regions. So they live on us and in us and they help us. In various ways. And very few of them are disease causing microbes. So it's very different from, you know, if you are infected with COVID or anything else.

For example, take something James wrote about in his book. There's a bacteria that's commonly found on our feet, and it seems like it helps prevent foot infections like athlete's foot, but it also smells horrible. So how does one strike a balance between, well, "these bacteria are seemingly good and useful," and also, "I don't want everyone around me to smell my feet?"

Yeah, that was a hypothesis from an evolutionary biologist. And usually when we have things about ourselves that we don't like, we'd say, like, why would we ever evolve to like have feet that smell offensive to everyone around us if we don't wash them regularly, you know. And usually it's because the thing that is causing that thing we don't like was also serving some other important purpose. And I think right now, if you smell a whiff of someone's foot that at all, and people will tend to you judge them poorly. But I think you don't want to do things that would kind of just offend the average person, want to go out smelling terrible or looking so unkempt and disheveled that people are, you know, think that you might be lost or intoxicated or something. But beyond that, you know, don't get too in your head about what really needs to be done.

So ultimately, as long as we're being hygienic, that is not contributing to the spread of illness and disease. Then it comes down to us, as consumers, and as people to decide which of our cleanliness habits are important to us and which we may be could live without. So I was left wondering if I wanted to change my own approach to cleanliness. Where should I start?

Well, it's intuitive. You know, the parts of the body that smell, they're the parts with the oily glands. So in your armpits and your groin are the places that most people continue to wash with soap with some frequency. Outside of that, it's very possible to do radically less. But I would not ever recommend quitting cold turkey. But you can take shorter showers, take cooler showers, use just less soap or detergent, body wash, shampoo and use less deodorant. If you like that and you become okay with it, you can continue weaning yourself and doing less and less and just see how you do with it. It's kind of like training for a marathon.

The idea of a marathon. I know way too many people who are running these things these days and it's it's not for me. I would collapse by mile three.

But that's what I'm saying, though, is yeah, you would if you just went out tomorrow and tried to run one. But if you really put your mind to it, you could do a half mile for every day for, you know, a month and work yourself up to a mile. You could get there and you would not die.

So it's time to put my hygiene to the test. After talking it over with my producers and coworkers and looking over my schedule. I've decided. Drum roll, please. I'm going to go a week without using deodorant. The results plus a convo with a dermatologist about what he recommends to his patients these days. Well, that's coming up right after the break.

So after all of this talk around hygiene, I was curious, what are dermatologists recommending to their patients these days?

We always say it's all fun and games until someone gets a rash.

This is Dr. Todd Kobayashi, who's been working as a dermatologist for over 20 years, and he agrees with the growing consensus in and around dermatology that here in the United States, we're overdoing cleanliness.

We probably are too focused on cleanliness, afraid of bacteria, afraid of viruses. And it's mainly in, I think, infants and kids where this occurs. When we are super clean, we're trying to sterilize everything in the house. Perhaps that exposure to those bacterial or viral pathogens as a child growing up ,makes the immune system less susceptible to developing allergies in the future.

So what do we need to do to be clean and healthy? Honestly, the list isn't all that long. Number one, and this shouldn't be too surprising given all we've heard in the age of COVID. Wash your hands.

It certainly decreases the amount of bacterial and viral pathogens on the skin, especially when you're talking about medicine. You know, washing your hands before touching a patient is kind of a standard for us. I have lots of patients that come in with hand dermatitis because they overwash. They're just washing too much.

So, okay. Number one is actually wash your hands, but don't overdo it. And I get it. A lot of people I know still follow the suggestions, like sing "Happy Birthday" to yourself while you wash your hands. But like Todd said, overwashing has led to a rise in hand dermatitis. So don't overdo it. Next on the list.

Brushing your teeth and, you know, flossing and all that is important, too, to keep the gums healthy. And if you want to keep your teeth when you're older and not have a bunch of holes drilled or pegs, it's probably a good idea to keep brushing on a regular basis.

But outside of that, it really depends on personal preference and context. For example, how often should people shower?

It depends on the person. Is is my answer. Because if if you are working out in the gym every day and sweating, or if you're working outside in the dirt, it probably reasonable to shower every single day if if not twice daily, in some cases. If you're staying at home, watching TV, reading a book, probably not necessary to shower every single day, maybe every other day or every third day.

So I decided to go a week without using deodorant. And I got to be honest, I'm not sure anyone could really tell the difference. Well, no one said anything to me anyway. What I noticed was that I would wake up in the morning. And to be frank, I'd stink it up. A few days in. I wrote in a diary entry, quote, "I haven't showered yet. I smell like absolute effing garbage. I'm hoping the shower does something." The next day, I wrote to myself, quote, "Laying in bed with no deodorant is rough." But once I showered, everything was okay. Now I do wonder what might have happened if I stopped showering, too. It could have gotten bad real fast. But I think this gets at a point that we've sort of been circling around this entire episode. We often do more than is strictly necessary. It's not that we should stop doing everything we do to be hygienic, but oftentimes in our pursuit of being clean, we tend to overdo it. Chances are that you could take out a thing or two from your cleaning routine and still be healthy and still be pretty clean too. Of course, whether or not you actually want to go that route. Well, that, my friends, is up to you. Coming up on our next episode. I've always wondered, why do people who wear glasses seem smarter than those of us who don't? And is there a chance that they actually are smarter next time? We'll find out. Margin of Error is a production of CNN Audio and Western Sound. Our showrunner is Cameron Kell. Our producer is Savannah Wright. Production assistance and fact checking by Nicole McNulty. Mischa Stanton is our mix engineer. Additional support from Tameeka Ballance-Kolasny, Dan Dzula and Allison Park. Our executive producers are Ben Adair and Megan Marcus. And me, well, I'm Harry Enten.