This Podcast Will Kill You - Special Episode: Jon Adams and Edmund Ramsden & Rat City

Episode Date: February 24, 2026

What happens if you put a bunch of rats in an enclosure and provision them with unlimited food and water? Researcher John B. Calhoun was committed to finding out. Results from Calhoun’s “rat utopia” experiments from the mid-20th century revealed a behavioral dark side that emerged as space grew increasingly limited, ultimately leading to complete population collapse. As headlines conveyed dire warnings about global overpopulation, Calhoun’s work served to reinforce those fears and shape our understanding of the importance of personal space. In this week’s TPWKY book club episode, Jon Adams and Edmund Ramsden join me to discuss their book, Rat City: Overcrowding and Urban Derangement in the Rodent Universes of John B. Calhoun. Tune in for a fascinating a tour through Calhoun’s bizarre and influential research, which even inspired a beloved (if a little creepy) children’s book and movie, Mrs. Frisby and the Rats of NIMH. Support this podcast by shopping our latest sponsor deals and promotions at this link: https://bit.ly/3WwtIAuSee omnystudio.com/listener for privacy information.

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Terms and Conditions Apply. Visit blueapron.com slash terms for more information. This is Bethany Frankel from Just Be with Bethany Frankel. Listen, I have a bone to pick with these dog food brands calling themselves fresh, natural, healthy. Sounds great, but a lot of these quote-unquote fresh dog foods in your fridge are not even 100% human grade, which is why feed your babies just food for dogs. It's good enough for big and smalls, my precious babies, so it's good enough for your babies. 100% human grade, real ingredients, beef, sweet potatoes, green beans, delicious.

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Janice Torres here. And I'm Austin Hankwitz. We host the podcast, Mind the Business, Small Business Success Stories, produced by Ruby Studio, in partnership with Intuit QuickBooks. We're back for season four to talk to some incredible small business owners. The big thing about working at tech is that it's ever evolving, ever changing. everyone's a rookie. That's how fast the industry is changing. So what I'm really excited about is to be part of that change. So listen on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hi, I'm Aaron Welsh, and this is This Podcast Will Kill You. Welcome to another episode of the TPWKY Book Club.

In this series, I bring on authors of popular science and medicine books and ask them a million and one questions about their books, about their process, and about them. I have loved putting these episodes together, and we have featured some fascinating books so far this season. If you'd like to check out the full list of books in the TPWKY Book Club from this season and seasons past, you know the drill. Head over to our website, this podcast will kill you.com, find the extras tab, and click on the link to our bookshop.org affiliate page. On that page, you'll find a bunch of podcast-related book lists, including one for this book club. I'm constantly updating these lists, so make sure that you check in regularly to see what books might be featured in future episodes or if there were any that you missed. Pro tip, these lists are great sources for gift ideas for the book lovers in your life.

If you have any books that you think would be a perfect fit for one of these episodes, please reach out through the contact us form on our website. We always love hearing from you all. A couple more pieces of business before moving on to the book of the week. And that is to first, please rate, review, and subscribe. It really does help us out. And second, you can now find full video versions of most of our newest episodes on YouTube. Follow Exactly Right Media's YouTube channel so you never miss a new episode drop. Imagine you're standing in line at a cafe waiting to place an order and the person behind you is just way too close.

You're stuck in the middle seat on a long flight battling with your seatmates over the two inches of armrest space. You're at a cocktail party, leaning further and further away from the Hall of Fame close talker who's been regaling you with an overly detailed account of their dream from last night. How are you feeling? Uncomfortable? Encroached upon? Stressed? I feel like my heart rate went up just thinking about the close talker. All these hypothetical situations and the discomfort they induce center around concepts familiar to all of them. us, stress and personal space. When we feel like our personal space is being invaded, it doesn't feel good. It feels bad. But this idea of personal space and how we feel about crowds or our

proximity to others is actually quite recent. The term personal space was only coined in the mid-20th century. Around that time, headlines proclaimed that humans were at risk of exceeding Earth's carrying capacity as the global population grew exponentially and urban centers swelled in size. And a handful of researchers grew increasingly interested in the physiological effects of stress, crowding, and population density. One of these researchers, John B. Calhoun, used rodents to forecast how human behavior might alter as available space shrank to non-existence. What he observed did not bode well for the future of humanity. In Rat City, overcrowding and urban derangement in the rodent universes of John B. Calhoun,

authors John Adams and Ed Ramston chronicle the bizarre story of Calhoun's rodent utopias, in which food, water, and bedding were unlimited, but space was not. The outcome? Chaos. Violence. Complete social breakdown. Calhoun's research captured the public's imagination and was employed. to promote a suite of dangerous ideas about population control and crime, all on the faulty logic that rodent behavior is equivalent to human behavior. It's not. I loved this fascinating and strange tale, and I'm really excited to share more of it with you all. So let's take a quick break and get started. Ed and John, thank you so much for chatting with me today. Thank you. Thank you. Thank you

been taking an interest. Thank you. I am just beyond thrilled to talk with you about John Calhoun, this mysterious and kind of bizarre John Calhoun and his rat experiments. I mean, my mind was utterly blown when I learned about the connection between these experiments and the Secret of Nim, which as a kid was one of my favorite movies and also is quite terrifying. I watched it recently, but we'll get into some of that later on. First, I would love it if you could give me a bird's-eye view, our rat's eye view of John Calhoun and his experiments and how you all came across them? I came across them really when I was doing my PhD and I was exploring the history of demography. So population sciences and relationship to eugenics and biological sciences in the 20th century U.S.

And while sort of demography as a field became increasingly social scientific, It moved increasingly to sociology and began to sort of push away from quite deliberately the influence of biology. I noticed that there was this experiment that just people kept referring to. And even people who were really, really critical of the influence of biological sciences in the social sciences. And this was the experiment by John B. Calhoun. So even in the 60s and 70s, they were referring to these rat experiments. of overpopulation. A lot of demographers were concerned with population control, you know, population bomb. And they drew from Calhoun's experiment when they were talking about

the ill effects of population density. So I was really intrigued, you know, why this attention to these experiments with rats by sociologists and social scientists that normally would not be drawn to these kinds of experiments. I wasn't an historian. I was working alongside Ned at the London School of Economics. And he was talking to me about this work he was doing on Calhoun and these weird rat studies. And I'm sure I had heard of him. Like when he was talking about the overpopulation studies and the rats going berserk, that rung a bell. I think I'd heard of the experiment somewhere, but I didn't have a name to it.

And I think that's a lot of people out there have that experience. They've heard of these experiments, but they don't. don't know where they come from. And in a sense, when we started putting the story together, that was us trying to sort of situate John Calhoun as a scientist, rather than just, you know, this kind of nutty professor with the strange box of rats. Which he does at some point kind of emerge or slip into that role of nutty professor. But we'll get to that part of the story later.

I kind of first want to go back to really the creature at the heart of this, which is the rat. And as you point out in your book, every city is a rat city. I mean, they are everywhere, globally distributed. How long ago did rats populate every continent? And what about them makes them so perfectly adapted to this cosmopolitan lifestyle? The contemporary thinking is that rats split off from mice into a separate species about sort of 10 million-ish years ago. So they were there long-bopold. for humans were there. And the first kind of evidence of there being kind of rat skeletons

mingled in amongst human sites of habitation is in the sort of late place to scene. So really, as soon as soon as you start getting communal dwellings, and this is over in Eastern Asia and modern day China, as soon as you had human habitation, seemingly you had rats living alongside them. So they've become what's called a commensal species, meaning that the two animals, live side by side, but don't necessarily harm one another. And then as human habitation spread out, the rats spread with them. And when trade routes opened up between the far east and into Europe, the rats traveled along the spice roads and came into Western Europe.

And then once trade routes opened up across the Atlantic, the rats came over almost certainly immediately. It will have been the black rat first, Rattus Rattus. and then subsequently the brown rat, which is, it's larger, it's better at most stuff than the black rat, and out-competed the black rat. And so it's the brown rat, the Norway rat, that you'll find in most American cities now, most Western European cities. Apart from some places, actually, though, because I think it's in California, up in the palm trees, because the rat is a much better climber. So it will still exist, but it does tend to be pushed aside by its much stronger cousin. I love rats and I find them so fascinating.

And the other thing I find truly fascinating about this is that for how ubiquitous these rats are in our cities, we know kind of surprisingly little about their ecologies, their behaviors, sort of just their everyday lives, they're in and out. What are they doing? And much of what we do know comes from this rat ecology project that John Calhoun ended up working on. How did he find himself on this research team, you know, moving from, I think Turtle Farms is where he got his start or one of the places he got his start to then these rat cities. Yeah, so John Calhoun was born in 1917, so when the Second World War came around, it was a young researcher at the time, and lots of kind of very smart people were shuffled around during the war years into jobs that they probably otherwise wouldn't have done. Some of them were pacifists, perhaps conscientious objectors. So they'd be put onto non-military but war-related work, work that could be of some kind of civic value. And the rodent, Ecology project emerged because Baltimore had a rat problem, which existed before the war. But when Baltimore ramped up production for the war effort in the early 1940s, the rat problem became an issue that the city thought needed fixing and quick.

So they hired a kind of crack team of scientists, and Calhoun was amongst the second wave of these. And, of course, the problem is when you hire scientists to do rat control, they don't just But miles of poison down, they get curious about the animals that they've been sent in to poison. And one of the first things they figured out was if they were going to successfully keep these numbers down, they had to understand the behavior of the rats. So Calhoun, who was an ecologist by training, joins this team and immediately becomes fascinated by the social lives of these animals. And as you say, there'd been almost no kind of investigative work studying the behavior, particularly of city rats. And one of the things the rodent ecology project scientists set out to do was to treat the city as the rat's natural habitat.

And therefore to come in with the ecologist's question of, okay, if this is their habitat, how do they live within it? It also came out through really as a consequence of some of the problems they faced in the earlier phases of the project. So the access to rodenticides, good ones, that they tended to use as one called Red Squill. and it came from the Mediterranean, so they didn't have their access to the normal rodenticides that they would normally get access to. So they had to devise their own. And to do this, they turned locally to Johns Hopkins University, where they had another leading figure in the study of rats, which was Kurt Richter. Kurt Richter was a physiologist who was busy studying, well, rat physiology, and he thought physiology determined so much of behavior. And he was looking at

what rats ate and why. And he became employed in trying to develop a new poison, which they did successfully. And even though they were sort of going out and killing hundreds, thousands of rats, the rat population wasn't being significantly dampened. And this was because they're very, very high rates of breeding, of reproduction. So the rat populations were really bouncing back. So they needed to rethink how are we going to actually dampen control this population? And they began to move from a kind of magic bullet approach through chemicals, chemical warfare, to an ecological approach. The rodent control project became the rodent ecology project. And ecologists began to take it over, also based at Johns Hopkins.

And one of the first things they noticed, once they were looking at it as a habitat, and as ecologists was the population numbers were located. And again, the city was quite useful for this. Baltimore's gridded into blocks, as many North American cities are. And the rat population within each city block was more or less the same as they were able to count them. There were about 150 rats per block. And they didn't cross the roads. Even if there was abundant garbage there for them to eat, the numbers never really got above 150.

And so for the ecologist, this is fascinating. You know, the normal model would say the population expands until it runs out of resources and then it collapses through starvation. But this wasn't happening. They were never overusing the space they had. They would limit their population numbers. And so that's the fascinating question that Calhoun set out to solve was how come the rats can practice birth control.

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I've been chatting with John Adams and Ed Ramston about their book, Rat City, Overcrowding and Urban Darrangement in the rodent universes of John B. Calhoun. Let's get back into things. you know, it started out as this sort of field ecologist, let's just observe and see what happens, and then that gradually kind of morphs into more experimental, let's manipulate some of these, you know, these block boundaries to then making this full-on kind of rat terrarium, which they did in the Towson enclosure. What did these enclosures allow the team to do that they couldn't do with these purely observational studies in Baltimore? Yeah, so they were rapidly approaching a kind of observational horizon within the city blocks

because there's only so much you can observe. People are obviously living in these houses, right? And whilst they could perch in the alleyways and watch the rats and sort of trace their footprints through the snow, at one point they put a dye in the food so they could follow blue rat feces around and see how many had been taking which routes. But they'd run out of observational room there. And they wanted to know more about the behavior of the rats within their habitat. So Calhoun had this idea that he would build an artificial city block.

And so he asks his neighbor out in Towson, which is just outside of Baltimore, he asked his neighbor, can I build a rat enclosure on this disused land? And his neighbor said, oh, sure, go ahead. You know, thinking he'd probably, you know, put up like a hutch or a small pen. Calhoun built a quarter acre enclosure, an area which he estimated covered about the available space that the rats would have within. a city block. So it was a one-to-one representation of a city block and he cut alleyways through it, high fences all around it. He installs some wild rats, builds an observation tower and then just

lets them be. There's a food hopper in the middle. There's water available. They've got nesting materials, but effectively it's a wild population of rats that are in there and they've got abundant space. And then he could study them day by day and did so. He was up every morning before work and every night sat in his observation tower with his binoculars with his glasses. For 27 months, he observes them, watching these life cycles go through, watching them form into colonies. And pretty much all that we know about the behavior of brown rats comes from Calhoun's very, very meticulous, detailed, over two-year study of their behavior within the Tausen enclosure. And he uses also the latest technology. So the U.S. Army is very interested in this.

because obviously they're trying to control rats not only at sort of bases within the US, but abroad as well. So they carry out some of the first films of the rats in their behavior through his experimental spaces. He borrows some snooperscopes, he calls them, these night binoculars that allows them to watch them at night. And he builds this tower, an observational tower, over the pen, which allows, allows him to watch all these rats whenever he can. And it becomes a kind of place where lots of people, other scientists, come to view rats. And it's through people coming to view these rats that he gets really his next chance in terms of developing his career and his next opportunities for studying these kinds of semi-artificial environments for understanding rat behavior.

I mean, I'm truly a man dedicated to his craft, just picturing him up there on the tower with his sneakoscopes. And I think what's also so fascinating about these experiments are the questions that he's asking. Because, of course, science doesn't happen in a vacuum. The questions that we are interested in are always guided in part by the things that society is excited about or nervous about or just preoccupied with in some way. And this seems to be especially the case with Calhoun. He seems like he gets increasingly interested in the effects of overcrowding on his rat populations, not long after the concepts of personal space or like the stress of crowds become popularized, which struck me, I could not believe how recent those concepts are.

And so I'm curious why these concepts formed when they did. One of the most important ones that comes in is the concept of stress. And stress, as we know it today, when we use this language all the time, you know, I'm stressed, and we understand that it has both psychological and physiological effects and indeed long-term stress. We understand can contribute to, you know, heart disease, diabetes, and so on, as well as mental health problems. But our concept of stress is really, really new. It's a 20th century construction. I mean, we did have ideas of sort of nervous disorders before that, neurasthenia.

But it is very much our modern concept of stress and stressors is a 20th century construction. And it really comes into vogue around World War II at the same time, 1930s and 40s. And one of Calhoun's colleagues on the project is an ecologist, but is also working with endocrinology. So he is looking at stress effects. So what he's seeming to understand is maybe what is actually lowering this rat population isn't, as we previously considered, you know, access to water food and so on. That is certainly part of it. But actually, it's stress. Because once you begin to close off access, it's not simply that they don't have enough food to eat so they struggle and get ill and die.

They get really stressed competing for these resources. And that has an effect on their bodies, on their hearts, on their livers, and they get diseases and they die. What Calhoun does in this environment is he creates what he describes as a rat utopia. Because here, they're going to get endless amounts of food, endless amounts of water, harborage. And he allows his population to grow. And as this population grows, he notices that the population is kind of restricted to the same number for about 150 rats. So he's trying to understand why is it that even with all these resources, this animal doesn't breed beyond this particular level. And the answer he finds is stress.

They're getting very, very stressed because they're competing with one another for space. There are territorial species to access to females, for example, for the males, or for the males, fighting a lot. And so the result is that some of the dominance are able to control the space within the pens and live relatively normal lives. But for the majority, they're forced into these sort of open spaces where they're competing with one another continuously, interacting with one another. There's a lot of unwanted interaction. Rats can't ignore one another like humans can. They continuously interact. That's increasing. their stress levels, which is causing them to physically break down. And so the death rate begins to

spike. At round about the same time, a little bit later into the 1950s, an entirely independent of Calhoun, there's what was then a mental institution in Canada, in Saskatchewan. And it became a kind of laboratory. The lead researcher there is an Englishman called Humphrey Osmond. And he attracted kind of researchers who wanted to look at how we treated people within institutions, people who were already mentally unwell. And Robert Sommer, as an American researcher, becomes fascinated by the way that the patients within the institutions would use space. And it's summer in the 1950s that introduces this concept of personal space. So obviously we had a notion of personal space before, but it became a term of art only in the 1950s.

and spreads almost immediately, along with stress, because it made sense to people. They could immediately recognize this sense of their being, someone standing too close to you, that's stressful, someone making eye contact, that's stressful. And that lack of privacy was causing the patients in the institutions to suffer far more than they needed to. So some are along with Osmond and an architect they also bought on board. They redesigned the spaces where the patients are housed so that they can, have privacy so that they can retreat from company if they want to, so they can mingle if they want to, and the population becomes less violent, less hostile, less frightened. And then those concepts

began to link up with the work that Calhoun is doing. I'm curious about the effect of stress on the rats. So when we're talking about these enclosures and we're talking about increasing levels of stress as there's more crowding, is there stress disparity among individuals or some rats simply much more or less stressed than others. So one of the things Calhoun was able to observe in the Towson enclosure, this great big quarter acre pen that he's got behind his house, is that the rats form into distinct colonies. So they're not just spread out breeding, you know, randomly with one another. Colonies form.

And about sort of 10 to 12 colonies would form within this quarter acre space. And amongst those colonies, there would be two or three pretty dominant colonies, which did nearly all the reproductive work. And there you would have maybe just one or two male rats and a kind of harem of 12 to 15 female rats. And most of the breeding was done within those colonies. The less successful colonies, which were spaced around and separate from each other,

they would very often have a greater male to female ratio and would perform almost no breeding work. And they would be the more stressed of the rat colonies as well. And at the very doldrums of that, you would have an all-male colony which did no reproductive work at all for obvious reasons. But it was certainly the case that the stress levels within the rats would then be arranged along that gradient of dominance. One of the nice things about stress is that it's measurable, physiologically measurable. It's one of the reasons it's so attractive. And so he'd take samples of his rats and pass them on to physiologists based at National Institute of Health, such as Julius Axelrod,

who really is, you know, big name in physiology, who would do some autopsies for him and they would be able to identify the sort of damage done to eternal organs. So they'd be sort of adrenal hypertrophy, atrophy of lymphatic structures, ulceration of stomach, heart disease and so on, among the more stressed animals that were lowered down really in the dominance hierarchy. Let's take a quick break here. We'll be back before you know it. Anyone who works long hours knows the routine. Wash, sanitize, repeat. By the end of the day, your hands feel like they've been through something.

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I'm Austin Hinkwitz. And I'm Janice Torres. Join us for Season 4 of Mind the Business, Small Business Success Stories from Ruby Studio and Intuit QuickBooks. We're back and talking to more inspiring small business owners about everything from the changing business landscape to the rise of artificial intelligence and how QuickBooks on the Intuit platform. helps you outdo what you're capable of. So outdo it with Intuit QuickBooks. Working in QuickBooks just makes it easier to run the business, right? There's so much that you need to do when it comes to running a business, building products,

setting up marketing campaigns. And to run a business, you have to make sure that your finances are in order. So it removes my anxiety from one side of it so that I can focus on everything else. Listen to new episodes of Mind the Business, Small Business Success Stories, other Thursday on the IHeartRadio app, Apple Podcasts, or wherever you get your podcasts. This is Bethany Frankel from Just Be with Bethany Frankel. Listen, I have a bone to pick with these dog food brands calling themselves fresh, natural, healthy. Sounds great, but a lot of these quote-unquote fresh dog foods in your fridge are not even 100% human grade, which is why

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Let's get into some more questions. Calhoun moves from these Towson enclosures to, he just kind of like keeps doing this, but more and more and like bigger different variables and these rat utopias to rat universes. And all of this is also happening, it seems, with this backdrop where headlines and books are shouting about the dangers of overpopulation and urban population growth. And we're going to exceed the carrying capacity of the earth, what will happen. And so how much is that influencing his own experiments, especially, you know, when he starts to do these in Casey's Barn, for instance? So when Calhoun's on the rodent ecology project, he's an employee of John's Hopper. He's subsequently hired by the National Institutes of Mental Health, which is a newly formed

post-war institution at the National Institutes of Health in Bethesda. And at the National Institute of Mental Health, he's looking at stress in these rodent populations. But because of the nature of that institution, he's very much invited by his employers to make connections with human populations. So it's unclear from reading his work when he starts thinking about. his rats as comparators to human populations, certainly by this period in the late 1950s, when he's at the National Institute of Mental Health and social stress is a topic of discussion in human societies and obviously of interest to the mental health of the American population.

So it's really at that point that he starts to make those connections. There's been an ecological concern about the sheer volume of humans on the planet that dates back to at least the 1940s. There was two books, Road to Survival by William Voight and Our Plundered Planet by Fepi Rosborn. And these two books really kind of kickstart the modern environmentalist movement. And they're both predicated on this idea that the Earth doesn't have an unlimited bouncy, right? And if we have billions and billions of humans upon it, eventually we're going to use up all the resources or we're going to damage the planet and degrade the environment so much that it will become uninhabitable, both for humans and for a large section of

our other biomass. So the overpopulation concerned from that ecological perspective had been bubbling away for a while. Post-war, that takes a slightly different slant. Rapid population growth was seen as a real problem for political stability in nations across the world, which had recently become free of colonial powers, but now there was a concern, of course, with socialism, with communism, and there was a sense that in order to stabilize these countries to make them more aligned with the West, you needed sort of to invest in their development. We needed to invest finances economically. We needed to support the development of their industries, their educational systems. but rapid population growth was going to completely destabilize all these countries.

It's going to restrict their development. And also within the United States itself, there was a sense that high population density led to a range of social problems, that it was the cause, the driver of social unrest. So population control was the language that was very prominent during this period. So Calhoun's work really chimes with this interest. This period overlaps with the experiments he's been doing with Rats at Casey's Barn as part of his work at the National Institute of Mental Health. And those experiments are unlike Tausen, which is very much an observational experiment, at Casey's Barn, he begins to really focus down on what happens to a population when the numbers get too high. It hadn't done within the Baltimore blocks because they self-regulated.

it hadn't done at Towson because they had enough room. So he shrinks the room down. This is where his attention shifts from general rodent behavior to the specific problems of elevated population densities. One of the first things he discovers is, as the rats become more and more densely populated and as the number of unwanted social interactions increases, beyond a certain threshold, all the behavioral norms break down.

And so at Casey's Barn, he sees this first kind of dramatic evidence of what happens to a population when it passes a certain threshold of density. And what happens is horrendous. You know, the males form gangs and attack the females, the mating rituals break down, the young and neglected, the family units which have been so stable and kind of harmonious

within Towson become chaotic. Pops are born and dropped on the floor and left to die or cannibalized by other rats. The violence becomes so kind of intense that the rats begin slashing and biting at one another in a way they never do in the wild. As soon as those results are published, it looks exactly like all these concerns people have with San Francisco, with New York, with Detroit. They're looking at the American cities. They're looking at Calhoun's work and immediately saying,

well, look, there must be some biological connection. We're too densely populated. The cities are driving as mad. And that's really in the early 1960s when Calhoun's work really hits the public in a big way. What we're seeing in these enclosures and these utopies, which is a not the most appropriate, I would say, word to describe what's happening with these, with these poor rats whose populations are crashing and are under a huge amount of stress. But what we're seeing are these crashes where in Baltimore and the Towson enclosures, we're seeing a population plateau. But here there are these extreme behavioral reactions, pathological togetherness and then like

behavioral sync. And these populations, like in Casey's Barn, are starting to, crash really dramatically. Can you describe some of what he is seeing when these populations are just crashing? Yeah, so I think the reason why these strange behaviors begin to emerge, the violence, the pathological togetherness, is because the design of the enclosure in Casey's barn is such that it allows the rats to congregate in the middle, and it doesn't allow them to escape. So in the wild or in a larger environment, they would never put up with those conditions. They'd have budded off and formed a new colony somewhere else and just got away from it.

But instead, these rats find themselves trapped in a place where they're not going to die of starvation, they're not going to run out of water. And that's an entirely unnatural situation. And it's sometimes said of Calhoun's work, well, these aren't natural environments. This isn't happen in nature. Calhoun's well aware of this. And that's kind of the point, because he's looking at cities and thinking, well, you know, those are artificial environments as well.

They congregate far more people in one place than you would ever normally get. And they effectively prevent those people from leaving. I mean, in theory, an individual can leave a city. But, you know, as everyone saw with Hurricane Katrina, for example, individuals very often can't leave a city, even when there's an emergency. So people don't have the agency that it sometimes looks like they have. So what he'd done with that enclosure is create a space which would generate artificially high levels of population density, and that's when he begins to see the behavioral breakdowns.

So the pathological togetherness was a term he used for rats, which would congregate all around the same feeding hopper. The rats would begin to associate feeding with having another rat next to them, because there was always another rat next to them when they fed. So they became conditioned to only feed when there were other rats there. And this effect spreads out, which means that all the rats will gather around a single hopper or they'll all gather around a single water bottle in great clusters, you know, 50, 60 rats all around the same food hopper whilst the other hopper's left completely untouched. They become almost addicted to the idea of proximity and that then sends their bodies into this catastrophic process of stress-related breakdown.

And the mortality rates just become enormous. You know, by the end of the experiment, the mortality rates are around 96%. Almost none of the young are surviving. And of course, at that point, the populations crash into a local extinction. But it's all because of the design of the room that he set up. He didn't know that would happen, but he did expect that the rats would distribute themselves unevenly.

He just didn't realize they would do it quite as catastrophically as they did. And that's what a behavioral sink is, really. It is the collection of these rats, pathological togetherness around in a particular spaces. And it's, you know, as he makes clear, the pejorative sense around the language is not accidental, right? It's not a positive thing. A behavioral sync is very destructive. It exacerbates the other pathologies that are found in the group. So it's not pathological in itself. It's an anomaly. Rats eat and drink alone, separate. it, there's a lot of violence in these spaces because they're continuously interacting with each other

and then violence will break out and there'll be a lot of biting and so on and a lot of a lot of death. And what he thinks it happens among the rats is really a breakdown of their more complex behaviours. So, you know, they become much more withdrawn. So that's a later pathology that he begins to look at. And earlier we talked about stress. He talks about animals that actually become de-stressed. They're so withdrawn. They're not stressed at all, but they're not actually competing and living as animals. They're not competing for, say, if they're male, for females, for access to food, for territory. They just have no social role in that mouse or rat society. They just sit on the floor, eat, drink, and preem themselves. And he describes

this group as beautiful ones and dropouts, but he's beginning to think rats are limited, in a sense, by their evolutionary development, by their biological template. Humans have the possibility, he's arguing, of adapting to the environments that we find ourselves. So there's a limit to which you can sort of compare humans and rats. That's his point. He's saying, look, human beings, we can actually study this, we can say, you know, we need to actually change the way in which cities are built, the way we relate to one another in order to overcome these kinds of problems. One of the things that we did, well, it's part of the project, we were really interested in saying, you know, where did Calhoun's work go? Where was it really influential? Because he's making these big leaps. So a lot of

ecologists who are doing work with crowding, looking at stress, they're looking at this. And they're saying, you are really, you know, making these massive jumps, these comparisons to human beings. So a lot of biologists think he's really sort of going too far away, really, I think, from the field. So we were interested, where does his research go? And some of the areas that it's really influential in are really psychologists who are looking at people in confined environments, where they really don't have a lot of access to space and a lot of freedom to move around. So prisons, hospitals, mental institutions in particular. But there was also a little spike around road rage incidents, for example, you know, whether or not that there is something going on here that explains, you know, this spike in sort of violence in crowded traffic.

So what's interesting, I think, for us as historians to see where this kind of research goes and why. And again, it's context. You're thinking of the American city, 1960s, 70s, concern over institutions. We have the Attica prison riot, for example. And it's kind of inevitable, I'm thinking that a lot of people are looking around for experimental evidence, for what they seem to see happening to the American city and American institutions at this time. The biologic explanation for these behaviours also means that people don't have to think too much about the political, right? For a certain section of the population, an account which blames all these

problems that American cities seem to be having in the 1960s on the biology of the human animal, it kind of lets them off the hook for having to address a lot of the social and political issues, which are almost certainly a more proximate cause. That's the other appeal, I think, of work like Calhouns is this turn to biology to explain problems that actually probably have their feet in politics. It's such a great example, I think, of how you have limited control or no control really over how other people might use your research once it's out there. And so it seems like some politicians used Calhoun's, the results from his experiments,

to endorse violence or an increased police. state rather than increasing a social safety net. It's like, oh, look, violence is inevitable. And so we can't do anything about that. We just need to increase police. And as you said, it's a way of being like, well, this is out of our control. We know what happens here. We have a limited resources. And so we should do this instead of preventing what this might look like. And I think then that sort of is when the comparison between humans and rats begins to slip. And the biologists are like, let's pump the brakes on this. There's a limit, but then other people don't see the limit necessarily.

Yeah, and I think Calhoun had always, he'd always caught it press attention, you know, for really early on. So he's getting visits by the Baltimore Sun when he's on the rodent ecology project in the 1940s, before he's even done the Tausen enclosure. So he liked the idea that people took an interest in his work. Compiling the research for the book, you get the sense that he was playing a very dangerous, game by allowing the reporters to run away with the ideas. And so he often wouldn't make the sensational comment himself. But if a reporter wanted to compare, you know, the dropout rats to the

dropout hippies of the 1960s, Calhoun would put his hands up and say, oh, well, I'm not making the comparison, but I suppose you could. And that's dangerous in as much as your influence runs away with you when you're no longer the author of the conclusions. And I think in courting as much press attention as he did, certainly by the late 60s and into the early 1970s, the dominant narrative is one which he's increasingly feel is slipping out of his control. It's very much doom and gloom. We're heading for societal collapse. There's too many of us. The problems with the cities are irresolvable.

Calhoun has this kind of positive message of, oh, well, actually, if we redesign the spaces, we could have a happier society. No one wants to hear that, right? not when you've got behavioral sinks and, you know, gangs and families falling apart to talk about instead. Later on, from the 1970s, he's running sort of two approaches to his research, two experimental systems, very closely linked. One is shocking, I suppose, shocking people into the dangers and realities of uncontrolled population growth. So, Universe 25, for example, is a mouse experiment. So it begins to move increasingly onto Mao. mice because they're easier to work with smaller, less complex for the kind of experiments that

he's doing. And here you have the construction of an environment which looks like something. When I first saw this, I just thought, you're something out, Blade Runner. I mean, it's really a sort of terrifying dystopia that he's created with these little apartment buildings up and down for mice. And he traces this experiment for over, I think it's like four and a half years, isn't it, John? Yes, it is, yeah. So he allows his population to grow, and he says, you know, this time, I'm not going to end the experiment early.

So four and a half years, the population grows and then begins to crash and decline to the point that the last mouse dies, I think, is reported in the New York Times with a death notice. I mean, it really does get a lot of attention. But this is a sort of really catastrophic view. I mean, at the end, the animals are so disturbed by their environment. withdrawn that they don't know how to reproduce, they don't know how to were young. So the population, he says, two years before it actually ends is over because they're not reproducing and then it's just the longevity of the remaining members. Even when he takes animals out of this environment and seeds them into a new environment, so these

are the most withdrawn, beautiful ones as he describes them, they look really healthy. he cedes them into a new environment. They don't reproduce. So on the one hand, he's producing experiments like this, which are really shocking, you know, that this could be the future of humanity. Yet on the other hand, he's also doing experiments where he's trying to temper the effects of overcrowding. Better design of physical space can mean that perhaps communities of rodents could live more normal lives among high density. he's trying to educate his rodents.

He refers to them as super rats at one point. In order to get a drink of water or food, they have to be next to another one. So the idea is that they develop a sense of cooperation, and he describes this again, leaping for comparisons with human beings in terms of altruism. And he believes that if he can culture his rats to sort of withstand some of the detrimental effects

of density, human beings with all their capacity, intellectual capacities, could actually design a future for humanity that was good, in fact, not just survivable, but a positive one. Because he thinks that these stresses, these challenges that we face as human beings can actually drive our societies as they have in the past into increased innovation. He thinks now we're at a sort of crossroads, he argued, And we have the opportunity really to redefine how we live and also reconstruct our spaces to make them more healthy. The problem is, is that people listen to the first message. They aren't drawn as much to the second. Of course, it's always the shocking bit, the doom and gloom that captures people's attentions and makes, that's the thing that people want to are drawn to, oddly. But that's not the only way that his work is capturing the public's imagination.

Of course, at the very top I mentioned the secret of NIM, which, I mean, I was speechless when I learned that NIMH refers to the National Institute of Mental Health. And in rewatching the movie recently, when they talk about the National Institute of Mental Health, I mean, I couldn't believe it. So can you tell me how Calhoun's work somehow finds its way into a children's book and movie? And so in the, I think it's the early 1970s, maybe late 60s, National Geographic send a reporter to Calhoun's lab at the National Institute of Mental Health, guy called Robert Conley. And we dug around, but as far as we can tell, Conley didn't actually write any article about Calhoun's work, but he definitely visited the rat rooms. Conley clearly didn't forget the encounter either, because a few years afterwards, he published Mrs. Frisbee and the Rats. of NIM, which is this story about a female rat who is struggling to save her family and encounters these super intelligent rats, which are the rats of NIM, which are rats which have escaped from

a laboratory and have these kind of human levels of skill where they can, you know, use electricity and machinery and they have language. Conley rather publishes this under the name Robert O'Brien, if the name sounds wrong, he used a pseudonym for his children's fiction. But the assumption is that those rats were inspired by the experiments he would have encountered Calhoun doing at the time on trying to create cultured and intelligent rats that were smarter than the average rodent. So that was an influence that Calhoun certainly didn't seem coming, but was always very, very proud of. He was very, very glad that at least one person had got the positive message out of his work, albeit only through the medium of children's fiction. Calhoun's experiments go so far, and they are invoked so often by politicians, by psychologists, by ecologists. I mean, they are, as you describe, hugely influential.

But then he kind of slowly slips from relevance over time. And he gets shoved aside at the National Institute of Mental Health. He resigns. And then he just kind of like fades away in a sense. what do you think his legacy is today? Like what mark do you think he left on science or society or the way that we think about space and crowds and populations? I think that as a group of thinkers and researchers

in the mid-20th century, he's really one of the first to get on top of this idea that our physical environment can positively or negatively affect our health. And that's very much, you know, I think that's a really normalized idea now. But when Calhoun and an anthropologist called Edward Hall and Robert Sommer, who was the psychologist who introduced the concept of personal space, when they were writing and they were very much collaborating with one another, they were turning people on to this idea that you could improve how a society functioned also by improving the physical environment in which you housed your citizens. So the idea that architecture should be sympathetic to the needs of the inhabitants and not simply act like a rack into which you stack a certain number of lab cages, that I think is one of the legacies of Calhoun's work,

taken as a part of that kind of revolution in design and architecture. I think, you know, for me, he represents this period in post-war United States, which was, there was a period of optimism, really, that social, scientists, biological scientists, psychiatrists, psychologists, could work together to solve a lot of these problems. And if you look at this sort of the government money that goes into institutions like the National Institute of Mental Health, a huge proportion of it actually goes to social scientists, what we describe as social psychiatrists, people who recognized, say, that the wider environment, as John said, the wider environment impacts our mental health. And that if you want to sort of address

issues of mental health in cities, you need to look at problems such as housing, such as employment. These are the fundamental things you need to look at, right? You're not going to solve them simply by increasing the research into pharmaceuticals, which is what his lab was actually, you know, he lost his lab because he was replaced by someone who was actually looking at how to develop new forms of antidepressants in their effectiveness. His concern with that was that all this sort of social science research into how we improve our environments was being lost. And that was very much the kind of narrative arc that we followed in Rat City was this sense of this work on social space and mental health. Just being really, it kind of collapses almost immediately when this new generation of psychopharmacological substances emerges.

these drugs offer a much cheaper and quicker and in the short term, more effective fix for society's mental health problems. And for two or three decades from the sort of mid-1970s onwards, drugs was the main solution. In fact, in the last few years, you've begun to see institutions like the National Institutes Mental Health turning back more to look again at these non-pharmacological interventions, but it was very much the rise of the mood drugs that did for Calhoun's work. And I think along with that as well was a growing political unease about the rhetoric of overpopulation. So it was no longer the done thing to talk about surging global population in terms of that being a problem that required fixing.

And there was also, I mean, that was kind of just as a perfect storm of science and policy sort of brought Calhoun's research to natural attention. It also created problems really by the 70s and 80s. As John said, there's a pushback against ideas of population control. There's also a backlash against sociobiology about, you know, this evolutionary psychology, the belief that humans are just like animals and that humans are inherently very aggressive territorial animals. So his work is associated with this. But also I think there is a sort of new, we're entering into a new neoliberal world really by the late 70s, early 80s, whereby there isn't this interest in funding large scale, long term, social, science, ecological research

projects. And a lot of the money is cut from these kinds of research programs. Again, kind of coming back to the work that is done, the science that has done, happens when it happens because of the broader world. And I feel like Calhoun's work really does illustrate that science doesn't happen in a vacuum. It's a product of all of the other things that are happening around him, who he is as a product of the environment that he grew up in and then is now participating in. And I just, I have to say, this has been just a really fascinating, conversation, and I really appreciate you taking the time to chat today. Oh, it's been marvelous. Thank you. Thank you. It's a pleasure. Thank you. A big thank you again to John Adams and Ed Ramston for taking the time to chat with me.

I love talking about rats. If you enjoyed today's episode and would like to learn more, check out our website. This podcast will kill you.com where I'll post a link to where you can find Rat City, overcrowding and urban derangement in the rodent universes of John B. Calhoun. as well as a link to Johns and Ed's websites where you can find their other work. And don't forget, you can check out our website for all sorts of other cool things, including but not limited to transcripts, quarantini and placebo-rida recipes, show notes and references for all of our episodes, links to merch, our bookshop.org affiliate account, or Goodreads list, a first-hand account form, and music by Bloodmobile.

Speaking of which, thank you to Bloodmobile for providing the music for this. episode and all our episodes. Thank you to Leanna Squalachi and Tom Breifogel for our audio mixing. And thanks to you listeners for listening. I hope you liked this episode and our loving being part of the TPWKY Book Club. A special thank you, as always, to our fantastic patrons. We appreciate your support so very much. Well, until next time, keep washing those hands. This is Bethany Frankel from Just Be with Bethany Frankel. Listen, I have a bone to pick with these dog food brands calling themselves fresh, natural, healthy. Sounds great, but a lot of these quote-unquote fresh dog foods in your fridge are not even 100% human grade, which is why

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