Is Your Gut a Second Brain?

We’ve got a great new episode today. And in addition, I’m excited to announce a new high school that we are launching in the fall of 2025 in Tempe, Arizona. More on that at the end of the episode. But just to let you know that we are searching for a school leader. And if you know someone who might be a good candidate, definitely spread the word.

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My father is a gastroenterologist and he loved to talk about his work. So more often than not, when I was a kid, dinner conversations centered on bodily functions, and you wouldn’t believe the things that would go wrong with my father’s patients. So for me, talking with today’s guest, Elsa Richardson reminds me a lot of my childhood. Elsa is a medical historian at the University of Strathclyde, whose most recent book is entitled Rumbles: A Curious History of the Gut.

RICHARDSON: I wouldn’t like to have had surgery before the invention of anesthetic. And there’s certainly many modern medical discoveries that I’m very thankful for. However, there are things that I think that we, in the history of Western medicine, have left behind that I think perhaps there is call for us to rediscover.

Welcome to People I (Mostly) Admire, with Steve Levitt.

As extreme as the conditions my father’s patients had to endure, none of them experienced anything like a man named Alexis St. Martin, which is where my conversation with Elsa Richardson begins.

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RICHARDSON: So Alexis St. Martin had the unfortunate luck of being shot through the stomach. So he was in a kind of general store out in the wild and he was shot with a musket through the stomach. We’re in the middle of the 19th century here. He was not expected to survive this. It was quite catastrophic. And, astonishingly, Alexis St. Martin survived. But he had what was basically a kind of doorway into the belly, a kind of open fistula, leaving this window into the gut.

LEVITT: So you could look directly into his stomach?

RICHARDSON: You could look directly into it. Yes.

LEVITT: So were gastric juices spilling out and things like that, or no? 

RICHARDSON: Yes, gastric juices were spilling out, so it was quite seepy, as you might imagine. Quite disgusting. And I think that most doctors — I hope most good physicians would think the first thing to do might be to find a way to seal up that wound, right? 

LEVITT: Seems pretty straightforward.

RICHARDSON: You would hope so. However, his doctor William Beaumont instead saw something of an opportunity. So what he recognized in this kind of remarkable wound was the possibility of better understanding something that had baffled medical authorities for a long time. Up until this point, there’d been this big argument between doctors as to exactly how digestion occurred. So was digestion a matter of motion? Did the stomach just grind up food? Or was it the work of some kind of chemical in the stomach? Or was it a combination of the two things? So what William Beaumont saw was the opportunity to test this, so to really understand what was going on in the gut when food was introduced. So he would get lengths of string, and he would attach different foods to it, so let’s say a little bit of chicken or a bit of apple, and he would lower them slowly into the kind of gaping wound, this fistula, in St. Martin’s stomach, and he would then time how long things took to digest. He would then take the food out and measure the acidity of the juices that were produced and do all kinds of experiments, which basically led to him, really for the first time, understanding a lot about the way that digestion works in the body. I guess what was remarkable about it in a way is that you can open up the body and you can take out certain organs, and there are other organs which continue to make sense outside of the body. Think of the heart, let’s say. You take a heart out of a dead body, you can dissect it, and you can see its ventricles, and you can understand its structure, and get a sense of how this big pumping machine might work. The stomach, on the other hand, has proved more of a kind of tricky proposition because when you remove it from the body, it ceases its functionality in a sense, right? It becomes deflated. It doesn’t make sense unless it’s in motion basically. So this opportunity to look into the stomach of someone still alive, right, offered this really unique opportunity to see, in real time, the work of digestion.

LEVITT: Now this doctor, so he’s not a research doctor at a prominent Ivy League university. He’s some regular old guy out in the middle of Wisconsin, before Wisconsin is anything, right?

 RICHARDSON: He’s not especially prominent, no.

LEVITT: But it’s just — it’s interesting that his first instinct was, “Oh my gosh, I’ve got this patient who can make me famous as a research subject,” when I think if you took a modern doctor working in a rural hospital, his response would be, “I have 15 patients waiting for me. I don’t have time to mess around with this guy with a hole in his stomach. Let’s get on with it.”

RICHARDSON: Yeah, or the care of your patient might be your first — your first instinct might be to seal up that gaping wound in your patient.

LEVITT: If I understand the story correctly, Alexis St. Martin couldn’t find work afterwards and he more or less became an indentured servant to this doctor, who paid him a trifle of money to allow him to keep on dipping this food into his stomach, which — obviously I think the patient would have chosen a different path had he had more power or status.

RICHARDSON: I think, one, just the fact that he doesn’t seal up the wound in Alexis St. Martin’s stomach right away, part of what I think that speaks to is — I think if we’re to tell a kind of heroic story about a pioneering doctor, then it speaks to his curiosity. And certainly the way that he would tell it would be that it’s his drive to further medical knowledge, to make this breakthrough. I think the other way that I think we might look at it now is to say, no, actually what this reveals is a huge power differential between these two people — that Alexis St. Martin does not have the agency and the power to be able to say, “Actually, I would really rather that you sewed this up and just stopped dipping bits of chicken into my belly.” There is this kind of strange relationship that gets struck up between the two of them in which Alexis St. Martin is basically under the control of William Beaumont, who basically keeps telling him that he will eventually sew up the hole in his stomach, he will eventually put him right, and that he will be paid for this work and be paid as an experimental subject, and there’s a lot of promises made. And you can imagine how maybe perhaps Beaumont goes in with the best intentions. He does think, “I’m going to do a week of experimentation and then I’ll get my results and then I’ll do what I need to for my patient.” That’s not what happens. So he pushes and pushes and pushes it back until eventually Alexis St. Martin is forced to flee. And basically goes into hiding because obviously Beaumont has also made him sign a load of contracts, legally bound him in certain ways, which means that he essentially has to spend the rest of his life flying under the radar a little bit then. Then, when he dies, his family are so concerned that Beaumont is going to attempt to procure St. Martin’s corpse to take on a kind of, you know, show-and-tell roadshow.

LEVITT: Oh, yeah.

RICHARDSON: That I think what they do is they leave Alexis St. Martin’s body to enter a state of quite kind of advanced decomposition before they go ahead with the burial, just so that they know that it would be useless for the doctor. So he stays with them until after death even.

LEVITT: One of the things that was interesting to me as I’ve read this in your book, Rumbles, is that it just shows how little we knew about even the most basic things about digestion into the 1800s. And I guess the primary source of information we had before Alexis St. Martin, much of it came from these horrendous experiments that were being carried out on living animals like dogs. So again, it doesn’t shine a very positive light on the medical profession. But can you talk about these dog experiments that were going on?

RICHARDSON: Sure, so they actually took place after Beaumont’s work. And the experiments I talk about in the book were undertaken at University College London, and they were undertaken by Ernest Starling and William Bayliss, who are these physiologists. And they conduct these experiments using dogs. So dogs’ digestive systems — so if you think of, like, Pavlov, for example — dogs’ digestive systems have often been used as a kind of substitute for the human, right? They’ve often been — what’s the word?

LEVITT: Proxies.

RICHARDSON: Proxies. There we go. Exactly. Proxies for the human. These experiments are undertaken on living animals. So they’re instances of vivisection. So basically what that means is that it would anesthetize the dog. Then they would open up the dog and conduct experiments on the living animal. After that they were required by law to then destroy the dog afterwards. What they’re interested in looking at in these unfortunate dogs’ digestive systems is, one, mapping the enteric nervous system. So the enteric nervous system is the bit of the nervous system which governs digestion and governs kind of gastrointestinal processes. So they’re interested in learning more about the kind of nervous structure of that bit of the body. And relatedly, part of what they discover in their investigations is that they uncover for the first time the existence of hormones. So this is when hormones get named. And one of the first ones they discover is a hormone that operates within the pancreas. And basically, before the thinking had been that the brain sends a signal to the pancreas to begin secreting certain pancreatic juices. What Bayliss and Starling managed to prove through various horrendous experiments with dogs was that actually that wasn’t what was happening. What was happening was that there were hormones within the pancreas, which were the — kind of the signaling devices and that they were actually getting most of their information from the enteric nervous system. Now part of what was remarkable about that was, one, our first understanding of hormones in the body, and two, this idea that the enteric nervous system seems to be able to operate independently from the central nervous system. So rather than what had been presumed before — which is: the central nervous system is the kind of governing sovereign of the body — what this suggested was, here we go, we’ve got this other little principality hidden in the gut, which has its own kind of mode of rule and law.

LEVITT: Maybe this is an exaggeration, but it’s almost like a second brain. The gut is almost like a mind of its own in some sense.

RICHARDSON: Yeah, absolutely. And I think this is one of the places that our kind of current scientific thinking around the gut as a second brain and maybe popular scientific thinking around the gut as a second brain originates in for sure, is with these experiments. I think there are also longer threads that we can pull here. Certainly, the idea of the brain as the only governing force in the body is one which is not consistent throughout time. There are other models of the body that we might locate, let’s say, in the ancient world, or even in kind of medieval thinking around the body, which allow for an understanding of intelligence which is far more, like, dispersed. It’s not such a kind of centralized model of governance. So for example, someone like Galen wrote about this idea of an intelligence which includes the gut, specifically the stomach, as possessing its own kind of thinking.

LEVITT: But if Galen said that, it was just pure luck, right? Because he was wrong about almost everything, and he was just making stuff up. 

RICHARDSON: I mean he was consistently quite —

LEVITT: You don’t really want to give him very much credence, do you?

RICHARDSON: He was consistently quite wrong. But I like the way that he thinks about it. Because the reason that he thinks that the stomach has its own intelligence is that it can register its own emptiness. That might be incorrect or inaccurate to our kind of modern thinking but I think does speak to something about maybe a feeling that we have about our guts or a feeling that we have about our bellies as minded in some way, or as vocal, let’s say, perhaps in ways that other organs of the body feel less noisy.

LEVITT: So it wasn’t until the discovery of X-rays, near the end of the 1800s, that doctors really had a good tool for studying the gut. What could they do with X-rays that they couldn’t do before?

RICHARDSON: It’s so interesting, because this is not in the book, but I’ve been recently working on — do you know the Kellogg brothers? 

LEVITT: Sure.

RICHARDSON: Of cornflakes.

RICHARDSON: I’ve been — basically I’ve been working a little bit on the Battle Creek Sanitarium and looking at the kind of health program that one of the Kellogg brothers ran there. And they were huge fans of X-rays. So they were using them — I think this is the early part of the 20th century, and they’re using them probably a little liberally, by today’s standards. It seemed like everyone who came through got several X-rays. So they would do this kind of whole diagnostic procedure when a new kind of patient would arrive in which they would take lots of tests, lots of stool samples, blood samples, so on and so forth. And one of the things that they always did was to X-ray the intestine, X-ray the gut. And part of the reason that they did that was it would allow them to see any inflammation, any blockages, but also I think it was a really, like for them, I think a kind of really powerful mode of visualization. In the Kelloggs’ case, I think it lent a great deal of scientific weightiness to the kind of claims that they were making around the intestine, and around the benefits of a clean intestine in particular. They would take one X-ray when the patient arrived and then be able to point to, “Okay, here you can see a point of inflammation, or there’s clogs here, or it’s distended here. And then after you’ve done two months of this diet or whatever, we’re going to take another X-ray of your intestine and be able to see, Oh, look at all this, the improvement and how healthy it looks now.” It was fascinating to see the X-ray being used in a space which is not exactly medical, right? It’s much more of a wellness space.

LEVITT: But also my understanding is — didn’t they infuse food with barium or something that shows up on X-rays? 

RICHARDSON: Bismuth.

LEVITT: Bismuth, yeah. And then they would do X-ray after X-ray, watching as the food trickled through the body to try to understand what was left of it and how quickly things were going.

RICHARDSON: Yeah, absolutely.

LEVITT: These were not the Kelloggs. These were real doctors who —

RICHARDSON: No, but the Kelloggs also did that. One of the ways in which I think the X-ray is really significant in terms of the history of digestion is the way that it helps to eventually challenge and trouble what had become, or what was in danger of becoming, a kind of quite wrong-headed medical orthodoxy. So in around the late part of the 19th century, there’s this theory that emerges called autointoxication. I don’t know if you’ve come across that before, but —

LEVITT: No.

RICHARDSON: Autointoxication was a theory, a medical theory, which held that constipation was extremely dangerous. And the reason that constipation was extremely dangerous was because food sitting in the gut for too long, sitting in the bowel for too long, would begin to fester and become fecund and start leaking poisonous gases and bad bacteria back through the walls of the bowel and out into the rest of the body. And proponents of autointoxication held that this kind of leakage from decaying matter in the gut basically was the cause of kind of most diseases — everything from sleeplessness, infertility, through to cancer, through to depression. And what this led to was a kind of deep suspicion, I think, of the gut as a source of pollution in the body. And it meant that doctors who were proponents of autointoxication began either recommending or performing themselves really quite drastic surgeries. So William Arbuthnot Lane, who was one of the main drivers of autointoxication theory in Britain, was an extremely well-thought-of surgeon. He was Sir William of Brothnot Lane. A real innovator in terms of kind of orthopedics, made a number of surgical devices which are still in use today. But he also became completely obsessed with this problem of constipation and he eventually started removing quite large chunks of his patients’ colons. So the idea being that, in cases of, like, very chronic constipation and chronic autointoxication as he would describe it, if you remove a section of the colon, then what you’re doing is you are shortening the road that that matter has to go down. He performed hundreds of these operations, and eventually was hauled up before the British Medical Council, and he eventually chose to take himself off the medical register so that he could continue treating patients for what he described as autointoxication. I guess to bring it back to the X-ray, I feel like one of the ways that the British Medical Council begin debunking this idea of autointoxication is using new technologies like the X-ray, which are able to bring much more clarity to exactly what the transit of food through the gastrointestinal tract looks like on the inside.

LEVITT: You quote a doctor in your book, I think his name was Metchnikoff — 

RICHARDSON: Yes, Elie Metchnikoff. 

LEVITT: — who suggested that every child should have his or her large intestine and appendix surgically removed when two or three years of age.

RICHARDSON: Yeah.

LEVITT: Did anyone actually start doing that?

RICHARDSON: No one quite started doing that, but Elie Metchnikoff again was the president of the Pasteur Institute in Paris. He was an extremely famous and extremely well-thought-of microbiologist and an expert in many other fields. And his thinking that the child should have its colon removed at birth comes from, again, autointoxication, so this idea that matter sitting in the gut too long is absolutely poisonous for the body. More specifically, in terms of his work, Mechnikoff was responsible for — I don’t know another way to put it — but for setting off a great yogurt eating craze in Edwardian Britain. So people became absolutely enamored with soured milk products in the early part of the 20th century, and it was all mainly down to Metchnikoff. He was really interested in — like so many kind of tech bros are today — he was very interested in aging, and what ages us, and how we can stop aging. So one of the things that he notices is that there seems to be places around the world in which their populations are remarkably long lived, and what he sees as uniting those different places is the consumption of some form of soured milk product — places like Bulgaria, for example, and Turkey, and places where they drink soured milk. And he theorizes that what is happening is that it is somehow neutralizing or killing off bad bacteria in the gut, which is possible. I’m not sure. But what he then takes from that also is, he says, “Well, you know what? Aging is the result of inflammation and it’s the result of the work of particular bad bacteria lurking in the gut and lurking in the intestines.” And again, I think that part of what that leads to is this kind of slight suspicion or demonization of the gut as a kind of quite like suspicious organ, as something which is, yeah, not to be trusted, as a kind of somewhere where there’s something kind of putrid and fetid there, which is disrupting or has the power to disrupt and dysregulate the rest of the body.

We’ll be right back with more of my conversation with historian Elsa Richardson after this short break.

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LEVITT: Now, you wouldn’t know this, but my own father is actually an incredibly accomplished research gastroenterologist. 

RICHARDSON: No! 

LEVITT: Yeah, in 1986, he won the prize that they give out each year by the American Gastroenterological Association for the researcher who’s made the greatest lifetime contribution to the basic science of the gut. And very relevant to what we’re talking about, he attributes much of his career success to getting his hands on a machine called a gas chromatograph. So just like X-rays allowed people to debunk various things, he got this machine, this gas chromatograph, which allows you to figure out which chemical compounds are present in a sample of gas. And the technology had been available since the early 1950s, but I guess people hadn’t thought to apply it to the gut until my dad did it in the late 1960s. And the first thing he showed is that all of the hydrogen produced by the human body — and the human body produces lots of hydrogen — it was being made only by bacteria in the large intestine. And that flew in the face of the conventional wisdom that existed at the time. And he’s told me that the single sentence he’s most proud of having written in his academic career comes from a paper, I think it was published in 1971, and he wrote something like, “Differences in intestinal bacteria could have a profound but rarely recognized influence on the host,” meaning the human being. I think it was in another 20 or 30 years before the medical field started paying serious attention to the gut microbiome. But my dad, I think, was ahead of his time in that regard.

RICHARDSON: Certainly ahead of his time in that regard. For me, it feels like there’s a bit of a gap between, let’s say, the end of the 19th century, beginning of the 20th century, when bacteriology as a science comes to dominate thinking about the gut. And that is a kind of double-edged sword in a way, because I think bacteriology on the one hand is this amazing tool for revealing the kind of complexity of the intestinal flora, for thinking about the way that intestinal flora might — in your dad’s words, might act on the host. But it also comes freighted still into the 20th century with a slight suspicion, I think, about bacteria and bugs as being, well, pathogenic, in some way, or potentially pathogenic. Then it feels like there’s this kind of big gap, and then we come closer to the present where we have the microbiome, and the microbiome seems to be going in slightly the opposite direction, which is to say, the microbiome is this — I don’t know, a land of great promise, this idea of a kind of blooming ecosystem within that we all need to kind of support and nourish. And if we support and nourish it sufficiently, there are endless possibilities for what it might do for our health. And I wonder maybe that these two poles are both a little too extreme in the promises they’re making.

LEVITT: So you cite in your book papers published by prominent researchers that suggest that the gut biome is actually predictive of things like life expectancy, and it seems like that’s really important. Now, prediction — it’s not completely clear that the causal arrow goes from whatever bacteria you have in your gut make you live longer. It’s possible that if you’re going to live a long time, that that leads you to having particular kinds of bacteria for other reasons. But it struck me reading that, as I reflected that if I were a young doctor, a data-minded young doctor in particular, that I think I would pick that as my career. I’d bet my career on the idea that the gut biome in the future could prove to be a really, really important tool for affecting health. But let me flip that to you. If you were a young doctor, is that a place where you would invest your career?

RICHARDSON: Oh 100 percent. If I had a scientific bone in my body, that’s what I would love to do. But yeah, I think that it is an exciting field of research. The study that you cited there, that is both wonderful and terrifying in its implications. And I think that most scientists working in the microbiome and working particularly with the gut microbiome are really careful still not to over egg, right? There’s no kind of big promises being made, I don’t think, by respectable science at the moment as to, one, what those kind of results really mean, and two, how actionable or what kind of changes or what kind of treatments or what kind of lifestyle improvements we might, let’s say, derive from those results. I think most people working in the gut microbiome at the moment would say that we are at the very, very beginning of understanding what the kind of scope of the gut microbiome is and how it might affect health.

LEVITT: Yeah. So, way back in 2011, my co-author Stephen Dubner did a podcast episode on fecal transplants, and at the time, it seemed like it might be a truly transformative medical intervention. Could you explain what a fecal transplant is and talk about whether those procedures have lived up to those high, early expectations that surrounded it?

RICHARDSON: So a fecal transplant is basically — it is what it sounds like. So it’s taking a little bit of the feces of someone else into your own body. So usually this is done via a capsule, which will be filled with someone else’s feces. You will swallow that, or swallow several of them. And the hope here is that someone with perhaps a more populous, healthier population in their gut microbiome will be able to repopulate your own. There was definitely a period maybe five to eight years ago where fecal transplants were all over the news. There was, like, a lot of kind of hype about these. And it seems to my mind that they perhaps haven’t taken off in quite the way that they might have, and I do wonder whether that’s because of a kind of inbuilt disgust at the idea of the procedure that maybe, unless you are in quite dire straits, it’s maybe not something that you’re going to try first. I would also say that in these intervening years, there has emerged onto the market so many other products that are promising to improve gut health, but that perhaps don’t involve a tiny capsule of poo.

LEVITT: Mm hmm. It does point to us being at the very beginning of our journey of understanding, that we aren’t delivering particular bacteria which have been shown to be good. We just take a whole mess of whatever some other guy’s got. “Oh, he’s healthy. Let’s put that in you.” That seems like a real sign of our ignorance rather than our progress in some ways. I think the other thing, it’s this ecosystem. The numbers they quote about — what is it? — billions or trillions of bacteria inside of us. And it’s like an ecosystem in nature, where you look at the lion at the top of the food chain, and you could perceive that lion as good or bad, but of course, every creature has their role. And you can intervene by, I don’t know, culling the number of deer or getting rid of mosquitoes, but then the way that plays out through the whole ecosystem is very complicated and often has unintended consequences. And I suppose the microbiome inside of us is the same story.

RICHARDSON: Totally. And also, to extend the metaphor further, we also are really the beginnings of taxonomizing that ecosystem, right? When we look at that ecosystem, we are only able to name a few of the creatures living in that world. There are many others out there that we don’t have names for yet, or that we haven’t managed to isolate, that work has not been done on.

LEVITT: Yeah. As long as we’re talking about poop, maybe I can draw some attention to my own contribution to our knowledge about the gut. When I was still young enough that I was being potty trained, my dad was in charge of taking the poop that I had just done in a training potty, and he dumped it in the toilet. And he noticed that when he put it in there, it floated, and then some bubbles came off it, and it sank to the bottom. And no parent, except for my dad, would have the idea that this was transformative to our understanding of the human body. Because at the time, the idea was that any time that poop was floating, it was because of excess fat in the poop. And no one had ever had the idea that it might actually be gas. And so my dad said he literally went to the hospital and within two days had done an experiment where one of his residents had his whole life had floating poop and had been really nervous because, at the time, that was thought to be potentially the sign of liver disease. And he said, “I was always afraid to analyze it.” But so my dad had this guy poop and they put it into a beaker, and I think what they did was they put it under pressure and that caused the methane that was in there to be released from the poop and it sank to the bottom, and then when they unpressurized it, it rose back up. My dad said it was the easiest study he ever did. And it was published in the New England Journal of Medicine, and it actually changed people’s view of this maybe not so important factor. So that is my personal contribution.

RICHARDSON: What was it like to be potty trained by a gastroenterologist?

LEVITT: I have no recollection, but I will say growing up in our house, number one, there was a complete normalization of all bodily functions related to digestion. But there were deeper things, like you would open up the freezer and there would be stool samples. So you had to be careful not to just willy-nilly go in and start microwaving things. 

RICHARDSON: It really reminds me of — have you ever read Charles Darwin’s Expression of Emotions in Man and Animals.

LEVITT: I have not.

RICHARDSON: Well, part of what’s so wonderful about that is that he basically uses his infant children as his experimental subjects. He’s constantly, like, observing them and making sketches of them and noticing what kind of makes them laugh. I often think about how there must be a peculiar kind of attention that a child of a scientifically-minded parent gets.

LEVITT: Reading your book, it’s so easy to look at medical practices in the past and to laugh at how misguided they were. But it’s not so clear to me how that should make us feel about our current medical system. I think one view, and maybe the predominant one, is that modern medicine has really nailed it, that we’ve figured out how to do things. And another reasonable view would be, well, in a hundred or two hundred years, future generations are going to look back at what we do and they’re going to laugh at our so-called medical wisdom. So having studied, what’s your take on that?

RICHARDSON: I guess I disagree in that I think that looking back into the history of medicine doesn’t cause me to feel like, “Oh —” I don’t know. Maybe that’s not quite accurate. I wouldn’t like to have had surgery before the invention of anesthetic. And there’s certainly many modern medical discoveries that I’m very thankful for. However, there are things that I think that we, in the history of Western medicine, have left behind that I think perhaps there is call for us to rediscover. So I’m thinking here about things like the humoral model. So the humoral model of medicine is the model of medicine which kind of ruled through the ancient world into the medieval period, and basically was in kind of practice at least until the end of the 17th century.

LEVITT: So this is like the bile and the phlegm and stuff like that?

RICHARDSON: So there’s understanding that the body is ruled by these kind of four fluids, four forces in the body. You have black bile, blood, yellow bile, phlegm. Health basically relies on you keeping those in some kind of balance. So everything that would be a kind of intervention, a medical intervention, would be about bringing balance back to the body. So think about, perhaps, like bloodletting, for example, to have less blood in the body to balance things out. On the one hand, we can look at that and think, that’s clearly not really how the body works at all. But on the other hand, I think that there are certain, like, elements from humoral medicine that I think we can take. And one of the things I think about is the call for balance, the understanding of the body as one, right? A kind of holistic understanding of the body as intertwined and interlinked. So one of the things that happens with the increasing specialization of medical knowledge from around the middle of the 19th century onwards is that there’s this kind of way in which medical knowledge or the practice of medicine becomes quite compartmentalized. And anybody who’s ever gone to the doctor or to the hospital with a complicated medical problem probably will recognize what I’m talking about here, right? Where it’s, like, you have to be shuffled from specialist to specialist, and you hope that everybody has read your case notes and has an understanding of what’s going on overall. But that kind of model of doing medicine obviously has its kind of wonderful benefits. Specialization can be extremely useful in medical research and in the dedicated treatment of particular conditions. However, it does come with downsides. My thesis here is not that we should return to humoral medicine, but I think that one of the things it does better, perhaps, is to think about the body as a whole rather than as different separate, semi-autonomous systems in the body. Another thing that I think humoral medicine does really well is to think about the body in context. So everything about humoral medicine is about thinking about the body in the world. It’s not just that you have these different fluids or forces within your body; it’s also that, like, those forces and fluids within your body can be acted upon by external conditions. Then lastly, I think what humoral medicine does really well is really foregrounds, like, diet and foregrounds what we put into our bodies as being a way that we can directly intervene in health, but also as being a way that is something that can really set the body off balance. 

You’re listening to People I (Mostly) Admire with Steve Levitt and his conversation with historian Elsa Richardson. After this short break: why don’t economists and historians typically get along?

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For my guest, Elsa Richardson the book Rumbles was her first attempt to write for a popular audience as opposed to a small set of other academic historians. I asked her how she liked writing for this broader audience.

RICHARDSON: I think it was a joyously freeing process on one hand, because the book that I’ve written was a book written for a trade press publisher. So it’s not — it’s referenced, it’s footnoted, it’s very deeply researched, but it was not an academic book. So normally, my kind of bread and butter is academic writing. And in academic writing, especially in academic history, the requirement really is that you say something small, specific, deeply, deeply, deeply referenced, citation, citation, citation.

LEVITT: And probably not that interesting because you have to beat all the fun out of it to make sure that the critics won’t poke some tiny little hole in it.

RICHARDSON: Yeah, it can’t be, like, a pleasure to read, right? So for me, with this book, what I loved about it was the freedom, in a sense, to be able to say, “Okay, in one paragraph, I’m going to move from the Middle Ages to the 1950s. And there’s just nothing that anybody can do about it.” I really enjoyed that element of it. And I think in terms of a kind of research process, I guess I thought about writing the book in a number of different ways. So first of all, I thought, oh, maybe I’m going to write this chronologically. And then I thought, okay, maybe that won’t work. Maybe I’ll think about it geographically. Maybe I’ll do a kind of comparative study of Britain and North America, let’s say, or France and Germany. And that didn’t work either. And what I realized that I was doing was trying to place false barriers or false kind of end points and stop points where they weren’t really useful. What I realized that I was working with was a kind of set of metaphors, a set of themes and images and points of contestation that recur across time. And when I came across that realization, it opened up the research process so that I was able to think, okay, one of the ways that I want to think about the gut is through the lens of work, for example. And when I started thinking more thematically, that was when I was able to, I hope, begin knitting together these quite kind of different materials and sources and voices in order to be able to get at what I see as a set of long-held cultural narratives and scripts about the gut.

LEVITT: I think that’s really interesting to hear. But what seems so daunting to me about your subject is it seems to the reader like you have done a search of the entire written legacy of mankind and culled out everything that’s about the gut. And I just wonder how one actually does that. How do you find these little nuggets buried in what is a nearly infinite supply of historical writing?

RICHARDSON: One thing that was useful was two restrictions which were placed upon my research. One was that it begun towards the tail end of the pandemic. So what that meant was that my travel was really restricted. So when I first conceptualized the project, I thought, I’m going to go to the Battle Creek archives in Michigan, or I’m going to travel all over these places and go to all these different archives. But it just wasn’t possible. This was also restricted by the fact that I also had my son in this period, so I was also tied to an infant at all times. And what this meant was that I relied much more heavily on digitized materials. I was able to make some archival trips down to the Wellcome Collection Library, for example, in London, which is this incredible history of medicine collection. So I was able to go there a couple of times, but apart from that, really what I relied on were materials, historical materials, which had been digitized and which were available online. Now there’s two benefits of that in a sense is that, one, it does restrict, right? Like, I can’t look at the entire corpus of the world’s writing on the gut because I’m only able to see, in this case, what was available and what had been digitized. But what’s useful about digitized material online is that it’s keyword searchable.

LEVITT: I’m a lot older than you, and as a young economist, I spend a lot of time in the bowels of libraries, just looking at titles of books and opening them and searching. It was fun. Obviously, it was not very efficient compared to what you can do with digitized materials, but occasionally you would stumble onto things that you would never find because you didn’t know what you were looking for and your search was so diffuse. I suspect that historians romanticize that kind of search for knowledge. But on the other hand, I guess digitization has completely and totally transformed the process of writing history.

RICHARDSON: Or it’s in the process of transforming, I would say. So for example, this summer I was lucky enough to spend some time in the Harry Ransom library in Austin, which is just this, like, incredible collection of, like, 19th-century British materials, which have somehow made their way to Austin, Texas. And I spent maybe two or three weeks looking through the archives of one particular organization, so the British Sexological Society, and that felt like an experience closer to what you’re describing — getting material up from the stacks, not knowing what exactly was going to be in this folder. In that process, I feel like I was still able to find the unexpected. And also in that process, what also comes with it, which I think can be frustrating, but also useful, is, like, boredom or disappointment or frustration or worry that you’re never going to find anything useful and this has been a complete waste of time. And then eventually, you open the next folder and there is something bizarre and wonderful that sparks off all of that kind of thinking. And I think I agree that with digitization you don’t have that experience, but I don’t think historians are going to be extracting themselves fully from the kind of musty stacks anytime soon.

LEVITT: As you talk, it reminds me that I had one little experience as an amateur historian. It was super fun and it revolved around what’s called the Hawthorne effect. So there’s this result in psychology or maybe the economics of business, where, at a plant in Chicago, the Hawthorne plant, they would make changes to the environment that the workers worked in, and what they found is that every time they made a change, the workers were more productive. And then they’d make another change, and it didn’t really seem to matter what change they made — just the act of changing led to greater productivity. And that’s come now to have its own life as something called the Hawthorne Effect. And John List and I actually went back into the archives and we were able to do a little sleuthing and we found the actual hand-drawn charts and figures that collected all the data of those original experiments that were done in the, I think, the 1920s. And what was interesting is that what we were able to show is that it was just complete confusion on the part of the researchers. They were incredibly awful researchers. What happened was at this plant, the women who worked there, they worked six days a week, including Saturdays. And so the only time there was for the experimenters to go in and make a change to their environment was on Sundays when the plant was closed. But it turns out when you look at the data, that productivity on Mondays was just a lot higher than productivity on Saturdays. And so it was true, every time they made a change, they would compare the Saturday productivity to now the Monday productivity, and they would find these women were much more productive. But even when they didn’t make a change, they were much more productive on Mondays than Saturdays. What was interesting and funny for us is that this phenomenon, which now has a life of its own, it may or may not be true, but it absolutely was not true in the Hawthorne factory where it got its name. And I have to say, of the papers I’ve written, that was — I don’t know, I got the feeling that maybe doing history is more fun than doing economics, by and large.

RICHARDSON: I would agree with that. But I think also it speaks to, like, how enlightening going back into archives can be. Because I think that there’s this danger — and I think that’s a really wonderful example of the way in which, you know, without re-examining — and this is why I’m always telling my students to go back, primary sources, because unless you go back to the primary material what you’re doing then is you’re relying always on another person’s interpretation, reinterpretation, until it gets fifth or sixth hand. And I think that going back to the primary materials, as you did in that paper, can sometimes end up completely challenging the foundations on which those multiple interpretations have been made. And it’s interesting that the Hawthorne effect has a life of its own now, right? So I’m sure that you published that paper, which sounds like kind of a debunking paper, right? And that I can imagine probably that the term is still being used heartily in business economics or business psychology or wherever it’s popular.

LEVITT: Oh, yeah, our paper was completely ignored. People like the Hawthorne effect. They don’t want it to go away.

RICHARDSON: Yeah, exactly. I was going to say people don’t — I can imagine it’s the sort of thing that nobody really wants to hear that, because it’s something that feels common sense-y. It feels truth-y.

LEVITT: It’s also exciting because if you’re in business you need something to do all day. And so the idea that, “Wow, if I do stuff, good things happen” — that’s a very empowering idea. So it’s a welcome idea for people to say, “Hey, change is good. And so that gives me a reason to exist in the business.”

RICHARDSON: And that the focus is, as always, with productivity as being the kind of the key measure of success in that way. 

LEVITT: Now, we’re having a good conversation. But in general, historians really dislike economists, right? In your crowd, do you hold economists in very low esteem?

RICHARDSON: We’re just intimidated because you can do math.

LEVITT: It’s different. It’s a worldview. Because economists like things to be very simple. Our preferred view of the world is that principles are universal and you can write down one model, you can strip away all of the context, and what’s left in those mathematical equations tells you the truth. And that of course is completely antithetical to the worldview of the historians. And I think that’s why historians and economists don’t get along. It’s for real reasons we don’t get along.

RICHARDSON: Yeah, I would agree. I think there are definitely disciplinary and perhaps, maybe, ideological differences. Although I would say that I do think there are differences within history as a discipline. So certainly I am 100 percent one of those kind of woolly cultural historians, constructivist, “there’s no one meaning” types. However, if you were ever to go to, I don’t know, a conference of military historians or someone working on, let’s say, the history of the civil service in Britain between 1941 and 1960 — there’s definitely bits of history which I think are more aligned with perhaps the economist’s view of the world in that I think there are still historians out there who imagine what they’re doing is going to the archive or going to the sources and studying them very carefully, and then producing a true account of the history. “I have studied the sources. I have understood them. And now I will tell you the things that did happen.” I am very much a historian of health, a historian of culture and health, a historian of the emotions also, which is probably, I imagine, for economists, the woolliest of all history.

LEVITT: Yeah, we don’t have emotions, and emotions don’t exist.

RICHARDSON: Absolutely. Thinking bots. But I think this conversation is perhaps maybe an illustration of how historians and economists can sometimes get along if the conversation is structured mainly around poo.

Talking today with Elsa Richardson reminds me just how much I’d like to have my dad be a guest on this show. He’s an amazing storyteller, a brilliant thinker, and the person who’s most shaped who I am as a person. You might think most dads would be willing to go on their son’s podcast, that they’d be eager to do it. But you don’t know my dad. I think I’ve got a better chance of getting Taylor Swift as a guest on this show than I have with my own father. But as a substitute for doing an episode with my dad, I instead offer you something different. So just in case you’re interested, in the show notes to this episode, we provide a link to the speech that my dad made earlier this year when he retired at the age of 88. It’s one of the best speeches I’ve ever heard. It summarizes his 60-plus years of medical research in a remarkably understandable and personal way. I suspect if you watch it, you will see a lot of similarities between him and me. At least I’d be flattered if you did.

LEVEY: Hi listeners. Morgan here, the show’s producer. Steve made an announcement at the top of the show and he’s going to share more details about it now.

LEVITT: Yes, Morgan, I am so excited to announce that we are launching a brick-and-mortar high school, and it’s going to be located right smack dab in the middle of the Arizona state campus. We’re just pretending like we’re starting school from scratch and that the model we’ve been using for the last 150 years — we’re just pretending that doesn’t exist. It’s our belief that maybe the most important thing we can do is to give kids more ownership over their own education. What we do now is we tell kids what they need to learn. And honestly, most of what you learn in high school, isn’t very useful. It’s more of a marker that gets you on your way to college. So we want kids to actually be studying things that are interesting to them and that are useful to them in life.

LEVEY: Who’s we, Steve?

LEVITT: So “we” is my team at the University of Chicago, my RISC center, and Arizona State, which has been our partner in the Khan World School and is likely the most innovative university in the country, probably the world. And then also an education non-profit called the Blueprint Schools Network.

LEVEY: So we’ve had Sal Khan on the show a number of times, first to talk about Khan Academy, and then when he launched Khan World School. And you were involved in Khan World School. Your team created curriculum for the seminar classes. Is this new school connected to Khan World School in any way?

LEVITT: It’s really built off the success of the Khan World School. I think we were all really surprised at just how good the outcomes were for the students. Khan World School was a completely virtual school, an online school. And once you see that you can get those kind of results just online, it really felt almost like an imperative that we had to open an in person school because being in person offers you so many more opportunities. And that made us think that we could really create something very, very special.

LEVEY: So the school is opening in the fall of 2025. Can you give us a status report on what state the school is in right now?

LEVITT: Yeah. We have been working frenetically to try to create the ideas behind the school. We’ve got space, we’ve got funding, and now we’re trying to find an amazing school leader. And we’ve now got a job posting at ASU, which people can find in the show notes. And I encourage you, if you are a school leader or you know someone, please spread the word. We understand how important it is to have someone great in that position. We’re not quite yet ready to start accepting student applications, although that will come soon. And we’ve got a link in the show notes also for students who might be interested in attending. You can check that out as well.

LEVEY: What have been some of the biggest challenges in launching a school that you didn’t foresee?

LEVITT: So far it’s just been pure fun. It’s been nothing but exciting to be able to think through these ideas and try to imagine what we really would like school to be. I think where the biggest challenges are going to come, first, is getting kids to show up. It’s a big choice for kids and parents to say, “I’m going to try something new.” I deeply believe that it’s going to be an amazing experience for kids and their families. And then the second real challenge is, look, it all sounds good on paper, but when we actually have the kids in school, we’re going to get a lot of things wrong and we’re going to have to be nimble and respond to the challenges. But I think that’s the exact ethos that we’re trying to build into the school. We know we don’t know the answers. We know we’re trying to do something hard. But we think it’s important and we think we can deliver it. 

LEVEY: Okay, so do students have to be in person? And what’s enrollment cost for students?

LEVITT: It is an in-person school, so we won’t require kids necessarily to be there the entire day, but you do have to be able to attend, so you need to live in the Tempe, Phoenix area. And it’s free. It’s a public charter school under the Arizona State Charter, so anyone who attends will be attending completely for free.

LEVEY: Okay, finally, does this new school have a name?

LEVITT: It does have a name. I don’t know what it is though! You know me, Morgan. I’m not big into stuff like names. I don’t care what the name is. I just care about whether we give these kids an amazing experience.

LEVEY: Listeners, we will have links relevant to this new school in the show notes on our episode page. If you have a question for us, our email is PIMA@freakonomics.com. That’s P-I-M-A@freakonomics.com. If you have a question for Elsa Richardson about the gut, we can try to get that question to her and answer it in a future listener question segment. We read every email that’s sent and look forward to reading yours.

In two weeks, we have a brand new episode featuring Sarah Stein Greenberg. She’s the executive director of the Stanford d.School, their design school. And she’s an expert in helping people to unlock their creativity and apply it in their everyday lives. As always, thanks for listening and we’ll see you back soon.

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People I (Mostly) Admire is part of the Freakonomics Radio Network, which also includes Freakonomics Radio, No Stupid Questions, and The Economics of Everyday Things. All our shows are produced by Stitcher and Renbud Radio. This episode was produced by Morgan Levey with help from Lyric Bowditch, and mixed by Jasmin Klinger. We had research assistance from Daniel Moritz-Rabson. Our theme music was composed by Luis Guerra. We can be reached at pima@freakonomics.com, that’s P-I-M-A@freakonomics.com. Thanks for listening.

RICHARDSON: Remove the stomach from the body. Remove the stomach from the body. Removed from the body.