rat dystopia experiment

This Old Experiment With Mice Led to Bleak Predictions for Humanity’s Future

From the 1950s to the 1970s, researcher John Calhoun gave rodents unlimited food and studied their behavior in overcrowded conditions

Maris Fessenden ; Updated by Rudy Molinek

What does utopia look like for mice and rats? According to a researcher who did most of his work in the 1950s through 1970s, it might include limitless food, multiple levels and secluded little condos. These were all part of John Calhoun’s experiments to study the effects of population density on behavior. But what looked like rodent paradises at first quickly spiraled into out-of-control overcrowding, eventual population collapse and seemingly sinister behavior patterns.

In other words, the mice were not nice.

Working with rats between 1958 and 1962, and with mice from 1968 to 1972, Calhoun set up experimental rodent enclosures at the National Institute of Mental Health’s Laboratory of Psychology. He hoped to learn more about how humans might behave in a crowded future. His first 24 attempts ended early due to constraints on laboratory space. But his 25th attempt at a utopian habitat, which began in 1968, would become a landmark psychological study. According to Gizmodo ’s Esther Inglis-Arkell, Calhoun’s “Universe 25” started when the researcher dropped four female and four male mice into the enclosure.

By the 560th day, the population peaked with over 2,200 individuals scurrying around, waiting for food and sometimes erupting into open brawls. These mice spent most of their time in the presence of hundreds of other mice. When they became adults, those mice that managed to produce offspring were so stressed out that parenting became an afterthought.

“Few females carried pregnancies to term, and the ones that did seemed to simply forget about their babies,” wrote Inglis-Arkell in 2015. “They’d move half their litter away from danger and forget the rest. Sometimes they’d drop and abandon a baby while they were carrying it.”

A select group of mice, which Calhoun called “the beautiful ones,” secluded themselves in protected places with a guard posted at the entry. They didn’t seek out mates or fight with other mice, wrote Will Wiles in Cabinet magazine in 2011, “they just ate, slept and groomed, wrapped in narcissistic introspection.”

Eventually, several factors combined to doom the experiment. The beautiful ones’ chaste behavior lowered the birth rate. Meanwhile, out in the overcrowded common areas, the few remaining parents’ neglect increased infant mortality. These factors sent the mice society over a demographic cliff. Just over a month after population peaked, around day 600, according to Distillations magazine ’s Sam Kean, no baby mice were surviving more than a few days. The society plummeted toward extinction as the remaining adult mice were just “hiding like hermits or grooming all day” before dying out, writes Kean.

Calhoun launched his experiments with the intent of translating his findings to human behavior. Ideas of a dangerously overcrowded human population were popularized by Thomas Malthus at the end of the 18th century with his book An Essay on the Principle of Population . Malthus theorized that populations would expand far faster than food production, leading to poverty and societal decline. Then, in 1968, the same year Calhoun set his ill-fated utopia in motion, Stanford University entomologist Paul Ehrlich published The Population Bomb . The book sparked widespread fears of an overcrowded and dystopic imminent future, beginning with the line, “The battle to feed all of humanity is over.”

Ehrlich suggested that the impending collapse mirrored the conditions Calhoun would find in his experiments. The cause, wrote Charles C. Mann for Smithsonian magazine in 2018, would be “too many people, packed into too-tight spaces, taking too much from the earth. Unless humanity cut down its numbers—soon—all of us would face ‘mass starvation’ on ‘a dying planet.’”

Calhoun’s experiments were interpreted at the time as evidence of what could happen in an overpopulated world. The unusual behaviors he observed—such as open violence, a lack of interest in sex and poor pup-rearing—he dubbed “behavioral sinks.”

After Calhoun wrote about his findings in a 1962 issue of Scientific American , that term caught on in popular culture, according to a paper published in the Journal of Social History . The work tapped into the era’s feeling of dread that crowded urban areas heralded the risk of moral decay.

Events like the murder of Kitty Genovese in 1964—in which false reports claimed 37 witnesses stood by and did nothing as Genovese was stabbed repeatedly—only served to intensify the worry. Despite the misinformation, media discussed the case widely as emblematic of rampant urban moral decay. A host of science fiction works—films like Soylent Green , comics like 2000 AD —played on Calhoun’s ideas and those of his contemporaries . For example, Soylent Green ’s vision of a dystopic future was set in a world maligned by pollution, poverty and overpopulation.

Now, interpretations of Calhoun’s work have changed. Inglis-Arkell explains that the main problem of the habitats he created wasn’t really a lack of space. Rather, it seems likely that Universe 25’s design enabled aggressive mice to stake out prime territory and guard the pens for a limited number of mice, leading to overcrowding in the rest of the world.

However we interpret Calhoun’s experiments, though, we can take comfort in the fact that humans are not rodents. Follow-up experiments by other researchers, which looked at human subjects, found that crowded conditions didn’t necessarily lead to negative outcomes like stress, aggression or discomfort.

“Rats may suffer from crowding,” medical historian Edmund Ramsden told the NIH Record ’s Carla Garnett in 2008, “human beings can cope.”

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Maris Fessenden | | READ MORE

Maris Fessenden is a freelance science writer and artist who appreciates small things and wide open spaces.

Rudy Molinek | READ MORE

Rudy Molinek is  Smithsonian  magazine's 2024 AAAS Mass Media Fellow.

The Doomed Mouse Utopia That Inspired the ‘Rats of NIMH’

Dr. john bumpass calhoun spent the ’60s and ’70s playing god to thousands of rodents..

On July 9th, 1968, eight white mice were placed into a strange box at the National Institute of Health in Bethesda, Maryland . Maybe “box” isn’t the right word for it; the space was more like a room, known as Universe 25, about the size of a small storage unit. The mice themselves were bright and healthy, hand-picked from the institute’s breeding stock. They were given the run of the place, which had everything they might need: food, water, climate control, hundreds of nesting boxes to choose from, and a lush floor of shredded paper and ground corn cob.

This is a far cry from a wild mouse’s life—no cats, no traps, no long winters. It’s even better than your average lab mouse’s, which is constantly interrupted by white-coated humans with scalpels or syringes. The residents of Universe 25 were mostly left alone, save for one man who would peer at them from above, and his team of similarly interested assistants. They must have thought they were the luckiest mice in the world. They couldn’t have known the truth: that within a few years, they and their descendants would all be dead.

The man who played mouse-God and came up with this doomed universe was named John Bumpass Calhoun. As Edmund Ramsden and Jon Adams detail in a paper, “ Escaping the Laboratory: The Rodent Experiments of John B. Calhoun & Their Cultural Influence ,” Calhoun spent his childhood traipsing around Tennessee , chasing toads, collecting turtles, and banding birds. These adventures eventually led him to a doctorate in biology, and then a job in Baltimore , where he was tasked with studying the habits of Norway rats, one of the city’s chief pests.

In 1947, to keep a close eye on his charges, Calhoun constructed a quarter-acre “rat city” behind his house, and filled it with breeding pairs. He expected to be able to house 5,000 rats there, but over the two years he observed the city, the population never exceeded 150. At that point, the rats became too stressed to reproduce. They started acting weirdly, rolling dirt into balls rather than digging normal tunnels. They hissed and fought.

This fascinated Calhoun—if the rats had everything they needed, what was keeping them from overrunning his little city, just as they had all of Baltimore?

Intrigued, Calhoun built another, slightly bigger rat metropolis—this time in a barn, with ramps connecting several different rooms. Then he built another and another, hopping between patrons that supported his research, and framing his work in terms of population: How many individuals could a rodent city hold without losing its collective mind? By 1954, he was working under the auspices of the National Institute of Mental Health, which gave him whole rooms to build his rodentopias. Some of these featured rats, while others focused on mice instead. Like a rodent real estate developer, he incorporated ever-better amenities: climbable walls, food hoppers that could serve two dozen customers at once, lodging he described as “walk-up one-room apartments.” Video records of his experiments show Calhoun with a pleased smile and a pipe in his mouth, color-coded mice scurrying over his boots.

Still, at a certain point, each of these paradises collapsed. “There could be no escape from the behavioral consequences of rising population density,” Calhoun wrote in an early paper . Even Universe 25—the biggest, best mousetopia of all, built after a quarter century of research—failed to break this pattern. In late October, the first litter of mouse pups was born. After that, the population doubled every two months—20 mice, then 40, then 80. The babies grew up and had babies of their own. Families became dynasties, carving out and holding down the best in-cage real estate. By August of 1969, the population numbered 620.

Then, as always, things took a turn. Such rapid growth put too much pressure on the mouse way of life. As new generations reached adulthood, many couldn’t find mates, or places in the social order—the mouse equivalent of a spouse and a job. Spinster females retreated to high-up nesting boxes, where they lived alone, far from the family neighborhoods. Washed-up males gathered in the center of the Universe, near the food, where they fretted, languished, and attacked each other. Meanwhile, overextended mouse moms and dads began moving nests constantly to avoid their unsavory neighbors. They also took their stress out on their babies, kicking them out of the nest too early, or even losing them during moves.

Population growth slowed way down again. Most of the adolescent mice retreated even further from societal expectations, spending all their time eating, drinking, sleeping and grooming, and refusing to fight or to even attempt to mate. (These individuals were forever changed—when Calhoun’s colleague attempted to transplant some of them to more normal situations, they didn’t remember how to do anything.) In May of 1970, just under 2 years into the study, the last baby was born, and the population entered a swan dive of perpetual senescence. It’s unclear exactly when the last resident of Universe 25 perished, but it was probably sometime in 1973.

Paradise couldn’t even last half a decade.

In 1973, Calhoun published his Universe 25 research as “Death Squared: The Explosive Growth and Demise of a Mouse Population.” It is, to put it lightly, an intense academic reading experience. He quotes liberally from the Book of Revelation, italicizing certain words for emphasis (e.g. “to kill with the sword and with famine and with pestilence and by wild beasts ”). He gave his claimed discoveries catchy names—the mice who forgot how to mate were “the beautiful ones”’ rats who crowded around water bottles were “social drinkers”; the overall societal breakdown was the “behavioral sink.” In other words, it was exactly the kind of diction you’d expect from someone who spent his entire life perfecting the art of the mouse dystopia.

Most frightening are the parallels he draws between rodent and human society. “I shall largely speak of mice,” he begins, “but my thoughts are on man.” Both species, he explains, are vulnerable to two types of death—that of the spirit and that of the body. Even though he had removed physical threats, doing so had forced the residents of Universe 25 into a spiritually unhealthy situation, full of crowding, overstimulation, and contact with various mouse strangers. To a society experiencing the rapid growth of cities—and reacting, in various ways, quite poorly — this story seemed familiar. Senators brought it up in meetings. It showed up in science fiction and comic books. Even Tom Wolfe, never lost for description, used Calhounian terms to describe New York City, calling all of Gotham a “behavioral sink.”

Convinced that he had found a real problem, Calhoun quickly began using his mouse models to try and fix it. If mice and humans weren’t afforded enough physical space, he thought, perhaps they could make up for it with conceptual space—creativity, artistry, and the type of community not built around social hierarchies. His later Universes were designed to be spiritually as well as physically utopic, with rodent interactions carefully controlled to maximize happiness (he was particularly fascinated by some early rats who had created an innovative form of tunneling, where they rolled dirt into balls). He extrapolated this, too, to human concerns, becoming an early supporter of environmental design and H.G. Wells’s hypothetical “World Brain,” an international information network that was a clear precursor to the internet.

But the public held on hard to his earlier work—as Ramsden and Adams put it, “everyone want[ed] to hear the diagnosis, no one want[ed] to hear the cure.” Gradually, Calhoun lost attention, standing, and funding. In 1986, he was forced to retire from the National Institute of Mental Health. Nine years later, he died.

But there was one person who paid attention to his more optimistic experiments, a writer named Robert C. O’Brien. In the late ’60s, O’Brien allegedly visited Calhoun’s lab , met the man trying to build a true and creative rodent paradise, and took note of the Frisbee on the door, the scientists’ own attempt “to help when things got too stressful,” as Calhoun put it. Soon after, O’Brien wrote Ms. Frisby and the Rats of NIMH —a story about rats who, having escaped from a lab full of blundering humans, attempt to build their own utopia. Next time, maybe we should put the rats in charge.

Naturecultures is a weekly column that explores the changing relationships between humanity and wilder things. Have something you want covered (or uncovered)? Send tips to [email protected] .

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• ACCESSIBILITY

Calhoun’s prophet rodents and the creation of the “behavioural sink”

Sophie Calabretto

Dr Sophie Calabretto is a mathematician specialising in fluid mechanics. She is Honorary Senior Lecturer at Macquarie University and Honorary Associate Professor, at the ACE Research Group, University of Leicester.

I first read Mrs. Fris by and the Rats of NIMH as a young’un. What I didn’t know at the time was that it was inspired by a series of experiments on population dynamics from the 1940s to the 1970s . The two studies, over a total of eight years, aimed to explore the effects of population density on behaviour.

John B Calhoun was a behavioural researcher and ethologist who spent the largest part of his career at the US National Institute of Mental Health (NIMH), in Maryland. His work spans six decades, from early experiments with rodents in the 1940s to his death in 1995. But he’s become recently spotlit for his work in 1958–62, starting with a quarter-acre pen of wild Norway rats, and a 1968–72 experiment with mice called Universe 25. Universe 25 was his research pinnacle – a “rodent utopia”.

Calhoun calculated that his pen of wild Norway rats (or brown rats, aka Parisian rats, Hanover rats, street rats, common rats, sewer rats, wharf rats… in essence, “rats” as you know them) could have a sustainable density of 5000, but the population strangely never exceeded 200. With extremely high rates of infant mortality, by the end of the 27th month of observation the population had stabilised at 150 adults.

Calhoun and his team were surprised by these unexpected results and so embarked on a more controlled experiment involving a population of domesticated Norway rats, conducted in a converted barn (a step up in luxury for the animals).

Calhoun’s new rat palace consisted of a 3m x 4.3m room, divided into four pens by an electrified fence. These pens contained everything a rat could possibly need: food, water, elevated burrows, winding staircases, nest boxes… a rodent wonderland. Ramps connected pen 1 to pen 2, 2 to 3, and 3 to 4, but not pen 1 to pen 4. This meant that rats tended to concentrate in pens 2 and 3, leading to the development of what Calhoun dubbed a “behavioural sink”: a sort of voluntary overcrowding that resulted from the original, involuntary overcrowding, and led to significant changes in the rats’ behaviour.

These changes weren’t at the good end of the scale.

Among the male rats, behavioural disturbances ranged from “sexual deviation”, cannibalism, and frenetic overactivity to pathological withdrawal.

As a result of the population congregation in the middle pens, the rats became unnaturally accustomed to the presence of others. Eating and undertaking other “biological activities” were transformed into social activities, which they would only do in the presence of other rats. Although fine for eating (who doesn’t love a dinner party?), this disrupted the sequence of other normal activity, such as courting, building nests, and nursing and caring for their young.

In the worst-affected rats in a series of these experiments, infant mortality was as high as 96%. Among the male rats, behavioural disturbances ranged from “sexual deviation”, cannibalism, and frenetic overactivity to pathological withdrawal.

Now decades into his rodent studies, Calhoun’s aim had morphed into extending lifespan by creating a “Mortality-inhibiting Environment for Mice”, also known as Universe 25. Universe 25, like Calhoun’s decked-out rat barn, was created to cater for the wee experimentees in every way. The 2.7m x 2.7m metal enclosure had 16 vertical mesh tunnels, each with four horizontal corridors opening off at the top, and each corridor leading to four nesting boxes.

With each of these 256 nesting boxes capable of housing up to 15 mice, Universe 25 was theoretically capable of accommodating up to 3840 mice. (I know what you’re thinking right now: “I bet it didn’t”. Me neither, dear reader.) And, of course, there was an abundance of fresh water, food, and nesting material.

This is where everything starts getting a little… Biblical.

Calhoun’s reduction of mouse mortality was based on identifying the rodent equivalent of the four mortality factors listed in Revelation – as in the Book of Revelation. Calhoun described the results of the Universe 25 experiment in a journal article titled “Death Squared: The Explosive Growth and Demise of a Mouse Population”. His text included a hefty number of biblical references for something published in the Proceedings of the Royal Society of Medicine .

His lead paragraph ends thus: “This takes us back to the white first horse of the Apocalypse which with its rider set out to conquer the forces that threaten the spirit with death. Further in Revelation ( ii.7 ) we note: ‘To him who conquers I will grant to eat the tree of life, which is in the paradise of God’ and further on (Rev. xxii.2 ): ‘The leaves of the tree were for the healing of nations.’”

And so, along with its abundance of resources, Universe 25 was cleaned every four to eight weeks, contained no predators, had the temperature maintained at a delightful 20°C, and was colonised by the finest, disease-free mice selected from the National Institutes of Health’s breeding colony. The only limitation was space.

Unfortunately, what resulted was a turbo-charged rat barn all over again. The population of Universe 25 began to steadily grow from the four original pairs of mice, until it reached a population of 2200 by Day 560. At which stage the population began its decline, and by the end of the experiment (Day 1500), there were only 27 mice remaining. The last surviving birth occurred on Day 600, after which the incidence of pregnancies declined very rapidly with no young surviving. The last conception occurred around Day 920.

While dominant males initially thrived and fathered all the offspring they could muster, the less dominant were inactive and eventually became violent towards each other. Those who were attacked would later attack others. The female counterparts of the withdrawn males simply hid. Nursing females in the presence of territorial males began to exhibit aggression, attacking and wounding their own young and forcing them to leave the nest before weaning was complete.

The next generation of mice, having never experienced healthy mouse behaviour, had no concept of mating or parenting, or even territorialism.

Consequently, the next generation of mice, having never experienced healthy mouse behaviour, had no concept of mating or parenting, or even territorialism. Some – dubbed the “beautiful ones” – spent their time eating, drinking, and grooming themselves in seclusion. Elsewhere, mice formed gangs of cannibalistic, raping plunderers.

Gradually, with a cohort of mice who would no longer actively mate or engage constructively in society, the population died out.

Calhoun was concerned with not only the death of the body (the second death) but also the death of the spirit (the first death – see Revelation ii:11 ) – an unusual inclusion in an academic paper. His thoughts are summarised with a word equation, the penultimate entry in the article:

Mortality, bodily death = the second death Drastic reduction of mortality = death of the second death = death squared = (death) 2 (Death) 2 leads to dissolution of social organisation = death of the establishment Death of the establishment leads to spiritual death = loss of capacity to engage in behaviours essential to species survival = the first death Therefore: (Death) 2 = the first death

I have considered this equation for a while, and I have a few problems from a first-year university algebra perspective.

Let’s say mortality (bodily death) is a function called M . Now, as stated before, according to Calhoun’s article, there are five mortality factors in the ecology of animals in nature: emigration, resource shortage, inclement weather, disease, and predation. So mortality would be a function of these factors: M = M(e, r s , w i , d, p) . Now, the death of the second death would be the composition* of M with M , which we denote as M ∘ M . (*Function composition is when you apply one function to the result of another: for example, if f(x) = x + 1 and g(x) = x 3 , then (f ∘ g)(x) = f(g(x)) = f(x 3 ) = x 3 + 1 .)

This is where we hit a snag, because if we assume that M is a function of real variables, what we’re looking at is the composition of a multivariable function with a multivariable function, which isn’t technically possible.

Calhoun thought that the death of the spirit, which here equates to social breakdown, is unequivocally linked to the literal end of life.

But I digress. I think the most we can conclude from this is that Calhoun thought that the death of the spirit, which here equates to social breakdown, is unequivocally linked to the literal end of life. That is: “Loss of these respective complex behaviours means death of the species.” Unfortunately, he also concludes that “for an animal so complex as man, there is no logical reason why a comparable sequence of events should not also lead to species extinction”.

Many scientists, both at the time and since, would disagree with the somewhat macabre conclusions of the experiment, arguing that Calhoun’s work was not necessarily about population density per se, but rather it about social interaction. And humans interact with each other differently to the way rodents do. As a result, “Death Squared” is predominantly cited in works about lab rodents and rodent populations, rather than in research projecting the collapse of humankind.

Maybe Calhoun himself tried to soften his conclusions. At the end of the several pages of Biblical gloom in “Death Squared” he again relied on the Bible for the article’s last passage:

“Happy is the man who finds wisdom, And the man who gains understanding. Wisdom is a tree of life to those who lay hold of her. All her paths lead to peace.                 ( Proverbs iii. 13, 18 and 17, rearranged)”

Originally published by Cosmos as Calhoun’s prophet rodents and the creation of the “behavioural sink”

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MASONIC PHILOSOPHICAL SOCIETY

Seeking to recapture the spirit of the renaissance..

Masonic Philosophical Society

The Rat Utopia Experiments That Predicted Humanity’s Dark Future

Global population estimates exceeded 8 billion people in November 2022. That’s more people than have ever existed! In fact, a jaw-dropping 7pc of people who have ever lived are alive today. Surely, such a startling statistic should be front-page news. Yet it was hardly a blip. The soaring trajectory of human population growth over the past two centuries is now an accepted fact – an ascending rollercoaster without any sense of down.

That wasn’t always so. In the mid-twentieth century, the rampant population growth worried many who feared imminent overcrowding, overpopulation, and societal collapse. Short stories like Billennuim warned of a world of box-like apartments and pedestrian congestion lasting days, where every inch of land is devoted to housing or farming. Known as the neo-Malthusians (after 18 th -century scholar Thomas Malthus), they predicted a terrifying future if the rollercoaster of human population growth rose ever higher; they dared to look down.

Ethologist John Calhoun’s Rat Utopia experiments fueled these fears, pointing towards a spiraling degradation of normal social interactions. He coined the term “behavioral sink” to describe the so-called aberrant behaviors resulting from overcrowded population densities. It was the stuff of nightmares – at least to the nervous 1970s audience.

In the mid-twentieth century, the rampant population growth worried many who feared imminent overcrowding, overpopulation, and societal collapse.

Calhoun’s early experiments involved a 28-month study of a colony of Norway rats in a 10,000-square-foot outdoor pen. Beginning with five females, he predicted an exponential population rise leading to a theoretical 5,000 healthy progeny by the experiment’s end. In fact, the population never exceeded 200 individuals, stabilizing at 150. Surprisingly, the rats congregated in groups of roughly a dozen – the rat’s social limit.

Like the brutalist architects of the era, Calhoun’s next experiment was bigger and bolder. Inside the second floor of a huge barn, his team constructed a series of four rooms connected by three bridges, forming a U-shaped space. Inside each room was a drinking and feeding station.

Detailing the shocking findings in a Scientific American article, Calhoun revealed how the effects of density led to a brutal battle among males. In the earliest stages, the male rats struggle for status. Once they fixed their place in the social hierarchy, they ruled among the two rooms with only one bridge – the end rooms. This became a dominant male’s territory where females were kept. Most male rats, therefore, congregated in the middle two rooms.

Early in the morning, before the dominant males awoke, the subordinate males would roam the various rooms. However, if in the middle rooms after he awoke, subordinate males found it exceedingly difficult to reach their original quarters. They were trapped. After several defeats, these males would never attempt to cross the bridge. The dominant male would only tolerate subordinate males so long as they never attempted to mate with the members of his harem – and they never did. Rather these subordinate males would often attempt to mount the dominant male, which he generally tolerated.

Females living in the middle rooms, meanwhile, fell into a behavioral sink. They became less adept at building nests before stopping completely. Nor did they move their litter to safety when necessary – unlike the females in the harems. Infants were frequently abandoned and would die when they were dropped. High rates of maternal miscarriage and infant mortality followed.

Connections were naturally drawn to the sink estates and neighborhoods arising in the US and UK. But Calhoun was far from done.

Universe 25 would be his most ambitious experiment; involving a vast space suitable for thousands of mice, Calhoun ensured the mice had ample food, water, and nesting material.

Between day 1 and day 315, the population doubled every 55 days, reaching 620 mice. Following day 315, population growth doubled only every 145 days. During this period, normal mice social behavior broke down. Young mice were cast aside by mothers before they weaned; homosexual behavior became common; dominant males struggled to maintain their territory leading to increasingly aggressive female behavior.

As Calhoun described:

“At the peak population, most mice … [waited] to be fed and occasionally attacked each other. Few females carried pregnancies to term, and the ones that did seemed to simply forget about their babies. They’d move half their litter away from danger and forget the rest. Sometimes they’d drop and abandon a baby while they were carrying it.”

In the final stages of mouse utopia, some young male mice never engaged in sex or fighting. They devoted their time solely to grooming, eating, and sleeping, becoming known as “the beautiful ones.” Despite appearances, these maladaptive mice could not cope with the stresses of life.

By day 600, the mice lost all social skills required to mate. Females ceased to reproduce, and the beautiful ones grew in number, engaging solely in solitary pursuits. When Calhoun wrote the experiment, the final breeding male had died – the mouse utopia was marching toward extinction.

While many have criticized the experiment for its social ramifications, it’s hard not to be alarmed. The parallels with modern-day society are stark. Yet social scientists who have attempted to replicate the findings in humans struggled to find any association between social density and behavior. Whatever your opinion, Calhoun started a conversation that very much continues today.

• https://www.iflscience.com/universe-25-the-mouse-utopia-experiment-that-turned-into-an-apocalypse-60407
• https://everything-everywhere.com/universe-25-the-rat-utopia-which-became-a-rate-dystopia/
• https://fee.org/articles/john-b-calhoun-s-mouse-utopia-experiment-and-reflections-on-the-welfare-state/
• https://www.smithsonianmag.com/smart-news/how-mouse-utopias-1960s-led-grim-predictions-humans-180954423/

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Categories: Behavioral Science , History

Tagged as: Dystopia , Ethics , John Calhoun , Morality , Psychology , Rat Utopia , Society

Published by MPSWriterJoe

Philosophy writer View all posts by MPSWriterJoe

1 reply »

https://fineartamerica.com/featured/behavioral-sink-dawn-sperry.html https://fineartamerica.com/featured/unincumbered-dawn-sperry.html Thank you for more thorough coverage than what I found in creating the two above excerpts for a novelty newspaper and cartoon tabloid. Best Regards, Dawn

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Dr. Calhoun’s Mousery

The strange tale of a celebrated scientist, a rodent dystopia, and the future of humanity.

Lee Alan Dugatkin

240 pages | 12 halftones, 2 line drawings | 6 x 9 | © 2024

Biography and Letters

Biological Sciences: Behavioral Biology

History of Science

• Table of contents
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“A new biography nearly as quirky as its subject. . . . Dugatkin—an evolutionary biologist, science historian and prolific author who sifted through thousands of pages at the Calhoun archive in Bethesda—is an admirably thorough researcher. . . . Calhoun belonged to a generation of scientists who had no compunctions about straying from their disciplinary lane. He wrote poetry and sci-fi and consulted on humane prison design. Dugatkin captures the grand ambition of a man who gazed at rodents and saw the universe.”

Ben Goldfarb | Scientific American

"This stimulating scientific history from Dugatkin . . . recaps psychologist John B. Calhoun’s yearslong experiments on mice and rats in the 1960s and ’70s. . . . Dugatkin offers colorful accounts . . . and descriptions of the exigencies of the rat-race within them intrigue. . . . This fascinates."

Publishers Weekly

“ Dr. Calhoun’s Mousery is a brilliant reminder, from biologist and author Dugatkin, of how relevant some research remains even decades later. This story of a fascinating, complicated psychologist and his innovative, insightful, troubling studies of overpopulation in rodents is an absorbing read and a potent lesson in moral behavior—both of rodents and of humans."

Deborah Blum, Pulitzer Prize–winning author of "The Poison Squad: One Chemist’s Single-Minded Crusade for Food Safety at the Turn of the Twentieth Century"

“John Calhoun famously showed that rodential ‘society’ degenerates horrendously when rodents live at high densities. Politicians, urban planners, pundits, and criminologists then seized these findings, often distorting them when extrapolating to supposed inevitabilities about urban humans. Dugatkin gives us the life of Calhoun himself―often eccentric, with wildly expansive ideas, unclear as to just how much he wanted them interpreted imprudently. A fascinating read about an immensely influential scientist.”

Robert M. Sapolsky, author of the New York Times–bestseller “Determined: A Science of Life without Free Will”

“William Blake saw the world in a grain of sand. John Calhoun saw it in a mousery—a utopian apartment complex built for mice! Dugatkin’s brilliant, fast-paced account of Calhoun's research takes us on a whirlwind tour with stops along the way at the Royal Society in London, the Vatican, and Washington, DC. Dugatkin is both learned and lively, and his book is irresistible.”

Edward Dolnick, New York Times–best-selling author of "The Clockwork Universe" and "The Writing of the Gods"

“This engagingly written book revives the life and work of the almost-forgotten behavioral population biologist John Calhoun, whose discoveries on the crowding syndrome and social pathology in rodents had at that time far-reaching interdisciplinary implications concerning the consequences of human population growth. This book is a masterpiece of critical, scholarly biography and historical analysis of a field in behavioral biology.”

Bert Hölldobler, coauthor of the Pulitzer Prize–winning "The Ants"

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From rodent utopia to urban hell: population, pathology, and the crowded rats of NIMH

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• 1 Centre for Medical History, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, United Kingdom.
• PMID: 22448542
• DOI: 10.1086/663598

In a series of experiments at the National Institute of Mental Health, the animal ecologist John B. Calhoun offered rats everything they needed, except space. The resulting population explosion was followed by a series of "social pathologies"--violence, sexual deviance, and withdrawal. This essay examines the influence of Calhoun's experiments among psychologists and sociologists concerned with the effects of the built environment on health and behavior. Some saw evidence of the danger of the crowd in Calhoun's "rat cities" and fastened on a method of analysis that could be transferred to the study of urban man. Others, however, cautioned against drawing analogies between rodents and humans. The ensuing dispute saw social scientists involved in a careful negotiation over the structure and meaning of Calhoun's experimental systems and, with it, over the significance of the crowd in the laboratory, institution, and city.

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The Behavioral Sink

The mouse universes of john b. calhoun.

How do you design a utopia? In 1972, John B. Calhoun detailed the specifications of his Mortality-Inhibiting Environment for Mice: a practical utopia built in the laboratory. Every aspect of Universe 25—as this particular model was called—was pitched to cater for the well-being of its rodent residents and increase their lifespan. The Universe took the form of a tank, 101 inches square, enclosed by walls 54 inches high. The first 37 inches of wall was structured so the mice could climb up, but they were prevented from escaping by 17 inches of bare wall above. Each wall had sixteen vertical mesh tunnels—call them stairwells—soldered to it. Four horizontal corridors opened off each stairwell, each leading to four nesting boxes. That means 256 boxes in total, each capable of housing fifteen mice. There was abundant clean food, water, and nesting material. The Universe was cleaned every four to eight weeks. There were no predators, the temperature was kept at a steady 68°F, and the mice were a disease-free elite selected from the National Institutes of Health’s breeding colony. Heaven.

Four breeding pairs of mice were moved in on day one. After 104 days of upheaval as they familiarized themselves with their new world, they started to reproduce. In their fully catered paradise, the population increased exponentially, doubling every fifty-five days. Those were the good times, as the mice feasted on the fruited plain. To its members, the mouse civilization of Universe 25 must have seemed prosperous indeed. But its downfall was already certain—not just stagnation, but total and inevitable destruction.

Calhoun’s concern was the problem of abundance: overpopulation. As the name Universe 25 suggests, it was not the first time Calhoun had built a world for rodents. He had been building utopian environments for rats and mice since the 1940s, with thoroughly consistent results. Heaven always turned into hell. They were a warning, made in a postwar society already rife with alarm over the soaring population of the United States and the world. Pioneering ecologists such as William Vogt and Fairfield Osborn were cautioning that the growing population was putting pressure on food and other natural resources as early as 1948, and both published bestsellers on the subject. The issue made the cover of Time magazine in January 1960. In 1968, Paul Ehrlich published The Population Bomb , an alarmist work suggesting that the overcrowded world was about to be swept by famine and resource wars. After Ehrlich appeared on The Tonight Show with Johnny Carson in 1970, his book became a phenomenal success. By 1972, the issue reached its mainstream peak with the report of the Rockefeller Commission on US Population, which recommended that population growth be slowed or even reversed.

But Calhoun’s work was different. Vogt, Ehrlich, and the others were neo-Malthusians, arguing that population growth would cause our demise by exhausting our natural resources, leading to starvation and conflict. But there was no scarcity of food and water in Calhoun’s universe. The only thing that was in short supply was space. This was, after all, “heaven”—a title Calhoun deliberately used with pitch-black irony. The point was that crowding itself could destroy a society before famine even got a chance. In Calhoun’s heaven, hell was other mice.

So what exactly happened in Universe 25? Past day 315, population growth slowed. More than six hundred mice now lived in Universe 25, constantly rubbing shoulders on their way up and down the stairwells to eat, drink, and sleep. Mice found themselves born into a world that was more crowded every day, and there were far more mice than meaningful social roles. With more and more peers to defend against, males found it difficult and stressful to defend their territory, so they abandoned the activity. Normal social discourse within the mouse community broke down, and with it the ability of mice to form social bonds. The failures and dropouts congregated in large groups in the middle of the enclosure, their listless withdrawal occasionally interrupted by spasms and waves of pointless violence. The victims of these random attacks became attackers. Left on their own in nests subject to invasion, nursing females attacked their own young. Procreation slumped, infant abandonment and mortality soared. Lone females retreated to isolated nesting boxes on penthouse levels. Other males, a group Calhoun termed “the beautiful ones,” never sought sex and never fought—they just ate, slept, and groomed, wrapped in narcissistic introspection. Elsewhere, cannibalism, pansexualism, and violence became endemic. Mouse society had collapsed.

On day 560, a little more than eighteen months into the experiment, the population peaked at 2,200 mice and its growth ceased. A few mice survived past weaning until day six hundred, after which there were few pregnancies and no surviving young. As the population had ceased to regenerate itself, its path to extinction was clear. There would be no recovery, not even after numbers had dwindled back to those of the heady early days of the Universe. The mice had lost the capacity to rebuild their numbers—many of the mice that could still conceive, such as the “beautiful ones” and their secluded singleton female counterparts, had lost the social ability to do so. In a way, the creatures had ceased to be mice long before their death—a “first death,” as Calhoun put it, ruining their spirit and their society as thoroughly as the later “second death” of the physical body.

Calhoun had built his career on this basic experiment and its consistent results ever since erecting his first “rat city” on a quarter-acre of land adjacent to his home in Towson, Maryland, in 1947. The population of that first pen had peaked at 200 and stabilized at 150, when Calhoun had estimated that it could rise to as many as 5,000—something was evidently amiss. In 1954, Calhoun was employed by the National Institute of Mental Health in Rockville, Maryland, where he would remain for three decades. He built a ten-by-fourteen-foot “universe” for a small population of rats, divided by electrified barriers into four rooms connected by narrow ramps. Food and water were plentiful, but space was tight, capable of supporting a maximum of forty-eight rats. The population reached eighty before succumbing to the same catastrophes that would afflict Universe 25: explosive violence, hypersexual activity followed by asexuality, and self-destruction.

In 1962, Calhoun published a paper called “Population Density and Social Pathology” in Scientific American , laying out his conclusion: overpopulation meant social collapse followed by extinction. The more he repeated the experiment, the more the outcome came to seem inevitable, fixed with the rigor of a scientific equation. By the time he wrote about the decline and fall of Universe 25 in 1972, he even laid out its fate in equation form:

Mortality, bodily death = the second death Drastic reduction of mortality = death of the second death = death squared = (death) 2 (Death) 2 leads to dissolution of social organization = death of the establishment Death of the establishment leads to spiritual death = loss of capacity to engage in behaviors essential to species survival = the first death Therefore: (Death) 2 = the first death

This formula might apply to rats and mice—but could the same happen to humankind? For Calhoun, there was little question about it. No matter how sophisticated we considered ourselves to be, once the number of individuals capable of filling roles greatly exceeded the number of roles,

only violence and disruption of social organization can follow. ... Individuals born under these circumstances will be so out of touch with reality as to be incapable even of alienation. Their most complex behaviors will become fragmented. Acquisition, creation and utilization of ideas appropriate for life in a post-industrial cultural-conceptual-technological society will have been blocked.

If its growth continued unchecked, human society would succumb to nihilism and collapse, meaning the death of the species. Calhoun’s death-squared formula was for social pessimists what the laws of thermodynamics are for physicists. It was a sandwich board with “The End Is Nigh” written on one side, and “QED” on the other. Indeed, the plight of Calhoun’s rats and mice is one we easily identify with—we put ourselves in the place of the mice, mentally inhabit the mouse universe, and cannot help but see ways in which it is like our own crowding world.

This is precisely what Calhoun intended, in the design of his experiments and the language he used to describe them. Universe 25 resembles the utopian, modernist urban fantasies of architects such as Ludwig Hilberseimer. Calhoun referred to the dwelling places within his Universes as “tower blocks” and “walk-up apartments.” As well as the preening “beautiful ones,” he refers to “juvenile delinquents” and “dropouts.” This handy use of anthropomorphism is unusual in a scientist—we are being invited to draw parallels with human society.

And that lesson found a ready audience. “Population Density and Social Pathology” was, for an academic paper, a smash hit, being cited up to 150 times a year. Particularly effective was Calhoun’s name for the point past which the slide into breakdown becomes irretrievable: the “behavioral sink.” “The unhealthy connotations of the term are not accidental,” Calhoun noted drily. The “sink,” a para-pathology of shared hopelessness, drew in pathological behavior and exacerbated its effects. Once the event horizon of the behavioral sink was passed, the end was certain. Pathological behavior would escalate beyond any possibility of control. The writer Tom Wolfe alighted on the phrase and deployed it in his lament for the declining New York City, “O Rotten Gotham! Sliding Down into the Behavioral Sink,” anthologized in The Pump House Gang in 1968. “It got to be easy to look at New Yorkers as animals,” Wolfe wrote, “especially looking down from some place like a balcony at Grand Central at the rush hour Friday afternoon. The floor was filled with the poor white humans, running around, dodging, blinking their eyes, making a sound like a pen full of starlings or rats or something.” The behavioral sink meshed neatly with Wolfe’s pessimism about the modern city, and his grim view of modernist housing projects as breeding grounds for degeneration and atavism.

Wolfe wasn’t alone. The warnings inherent in Calhoun’s research fell on fertile ground in the 1960s, with social policy grappling helplessly with the problems of the inner cities: violence, rape, drugs, family breakdown. A rich literature of overpopulation emerged from the stew, and when we look at Calhoun’s rodent universes today, we can see in them aspects of that literature. In the 1973 film Soylent Green , based on Harry Harrison’s 1966 novel Make Room! Make Room! , the population of a grotesquely crowded New York is mired in passivity and dependent on food handouts which, it emerges, are derived from human corpses. In Stand on Zanzibar , John Brunner’s 1972 novel of a hyperactive, overpopulated world, society is plagued by “muckers,” individuals who suddenly and for no obvious reason run amok, killing and wounding others. When we hear of the death throes of Universe 25—the cannibalism, withdrawal, and random violence—these are the works that come to mind. The ultraviolence-dispensing, gang-raping, purposeless “droogs” of Antony Burgess’s novel A Clockwork Orange , which appeared in the same year as Calhoun’s Scientific American paper, are the very image of some of the uglier products of mouse utopia.

Calhoun’s research remains a touchstone for a particular kind of pessimistic worldview. And, in the way that writers like Wolfe and the historian Lewis Mumford deployed reference to it, it can be seen as bleakly reactionary, a warning against cosmopolitanism or welfare dependence, which might sap the spirit and put us on the skids to the behavioral sink. As such, it found fans among conservative Christians; Calhoun even met the pope in 1974. But in fact the full span of Calhoun’s research had a more positive slant. The misery of the rodent universes was not uniform—it had contours, and some did better than others. Calhoun consistently found that those animals better able to handle high numbers of social interactions fared comparatively well. “High social velocity” mice were the winners in hell. As for the losers, Calhoun found they sometimes became more creative, exhibiting an un-mouse-like drive to innovate. They were forced to, in order to survive.

Later in his career, Calhoun worked to build universes that maximized this kind of creativity and minimized the ill effects of overcrowding. He disagreed with Ehrlich and Vogt that restrictions on reproduction were the only possible response to overpopulation. Man, he argued, was a positive animal, and creativity and design could solve our problems. He advocated overcoming the limitations of the planet, and as part of a multidisciplinary group called the Space Cadets promoted the colonization of space. It was a source of lasting dismay to Calhoun that his research primarily served as encouragement to pessimists and reactionaries, rather than stimulating the kind of hopeful approach to mankind’s problems that he preferred. More cheerfully, however, the one work of fiction that stems directly from Calhoun’s work, rather than the stew of gloom that it was stirred into, is optimistic, and expands imaginatively on his attempts to spur creative thought in rodents. This is Robert C. O’Brien’s book for children, Mrs. Frisby and the Rats of NIMH , about a colony of super-intelligent and self-reliant rats that have escaped from the National Institute of Mental Health.

Cabinet and the author regret that a previous version of this article omitted its sources.

See press about “The Behavioral Sink” on Longreads.com and theatlantic.tumblr.com .

Will Wiles is a London-based author and journalist. He is deputy editor of Icon , a monthly architecture and design magazine. His debut novel, Care of Wooden Floors , will be published by HarperPress in February 2012.

• May 2022, Issue 1
• Foundations

Universe 25 Experiment

A series of rodent experiments showed that even with abundant food and water, personal space is essential to prevent societal collapse, but universe 25's relevance to humans remains disputed..

Stephanie "Annie" Melchor is a freelancer and former intern for The Scientist .

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J une 22, 1972. John Calhoun stood over the abandoned husk of what had once been a thriving metropolis of thousands. Now, the population had dwindled to just 122, and soon, even these inhabitants would be dead. 

Calhoun wasn’t the survivor of a natural disaster or nuclear meltdown; rather, he was a researcher at the National Institute of Mental Health conducting an experiment into the effects of overcrowding on mouse behavior. The results , laid bare at his feet, had taken years to play out.

Universe 25 Experiment Explained

In 1968, Calhoun had started the experiment by introducing four mouse couples into a specially designed pen—a veritable rodent Garden of Eden—with numerous “apartments,” abundant nesting supplies, and unlimited food and water. The only scarce resource in this microcosm was physical space, and Calhoun suspected that it was only a matter of time before this caused trouble in paradise.

Calhoun had been running similar experiments with rodents for decades but had always had to end them prematurely, ironically because of laboratory space constraints, says Edmund Ramsden, a science historian at Queen Mary University of London. This iteration, dubbed Universe 25, was the first crowding experiment he ran to completion.

As he had anticipated, the utopia became hellish nearly a year in when the population density began to peak, and then population growth abruptly and dramatically slowed. Animals became increasingly violent, developed abnormal sexual behaviors, and began neglecting or even attacking their own pups. 

Eventually Universe 25 took another disturbing turn. Mice born into the chaos couldn’t form normal social bonds or engage in complex social behaviors such as courtship, mating, and pup-rearing. Instead of interacting with their peers, males compulsively groomed themselves; females stopped getting pregnant. Effectively, says Ramsden, they became “trapped in an infantile state of early development,” even when removed from Universe 25 and introduced to “normal” mice. Ultimately, the colony died out. “There’s no recovery, and that’s what was so shocking to [Calhoun],” says Ramsden. 

Debunking Popular Interpretations of Universe 25

Calhoun wasn’t shy about anthropomorphizing his findings, binning rodents into categories such as “juvenile delinquents” and “social dropouts,” and others seized on these human parallels. Population growth in the 1970s was swelling, and films such as Soylent Green  tapped into growing fears of overpopulation and urban violence. In a 2011 article , Ramsden writes that Calhoun’s studies were brandished by others to justify population control efforts largely targeted at poor and marginalized communities. 

But Ramsden notes that Calhoun didn’t necessarily think humanity was doomed. In some of Calhoun’s other crowding experiments, rodents developed innovative tunneling behaviors, while in others, adding more rooms allowed the animals to live in the high-density environment without being forced into unwanted contact with others, largely minimizing the negative social consequences. According to Ramsden, Calhoun wanted these findings to influence the architectural design of prisons, mental hospitals, and other buildings prone to crowding. Writing in a report summary in 1979, Calhoun noted that “no single area of intellectual effort can exert a greater influence on human welfare than that contributing to better design of the built environment.” 

Relevance and Criticisms of the Universe 25 Experiment

Looking back on the Universe 25 experiment with present day scientific perspective, the limits of its interpretations are evident. The research was largely observational and subjective. Calhoun described his study as “not normal science,” referring to it instead as an “observation and reconstruction of a process.” 2 Observational studies have a higher risk of bias and confusing correlation with causation. 3 Scientists have suggested that Universe 25 suffers from inaccurate interpretation of experimental outcomes, methods, and potentially confounding variables, 4 which reflect information bias . 3 For instance, at the time that Calhoun presented and published Universe 25’s results, his peers inquired about unsanitary animal husbandry and a lack of quantitative stress hormone measurements as potential confounding or missing information pertinent to Calhoun’s conclusions. 2

Importantly, despite popular interpretations of Universe 25 deeming it informative about urban crowding, many human studies on crowding and population density have yielded inconsistent results. 4 Behavioral scientists today largely acknowledge that how humans experience and respond to crowding is governed by a range of individual-specific social and psychological factors , including personal autonomy and social roles or contexts. 4 In some ways, this aligns with how Calhoun discussed his Universe 25 findings, not as effects of population density per se but effects of altered social interactions . 2 Additionally, the Universe 25 experiment did not address systemic determinants of well-being at the time, nor does it reflect present-day systems that are endemic to the human experience. The societal implications of increased population density and its effects on human beings are a far throw from Universe 25’s experimental design and the behavioral changes that Calhoun observed in his caged rodent experiments. 2,4

Finally, from an ethical standpoint, Calhoun’s experiments would not be permitted today. The mouse universes that Calhoun created intentionally placed its study subjects into constructed environments that caused harm. The study conditions were maintained despite evident animal distress, and many preventable casualties ensued. 2 This goes against current regulatory safety standards for animal research. 5

Which scientist conducted the Universe 25 experiment?

• John B. Calhoun led the Universe 25 experiment , which examined the long-term effects of increasing population density and resulting social stressors on mice living in a constructed environment. 2

How many times was the Universe 25 experiment repeated?

• Universe 25 was one long-term experiment in a series of mouse studies. The entire research series involved Calhoun’s constructed Mortality-Inhibiting Environment for Mice , and each universe examined separate mouse populations and conditions. Calhoun stated that the Universe 25 experiment involved the largest mouse population and longest follow up period. 2

What is a behavioral sink?

• In overcrowding rat studies that Calhoun performed before the Universe 25 experiment, he observed that individual rats began to associate feeding with the company of other rats, which led to the learned behavior of voluntary crowding despite insufficient resources at a crowded site and available resources elsewhere. He termed this specific voluntary crowding a behavioral sink . 1 Calhoun also observed this learned behavior in mice during the Universe 25 experiment. 2

Were the results of the Universe 25 experiment reproduced by other scientists?

• The social effects of population density vary between organisms and populations. Calhoun’s work inspired many scientists to focus on behavioral studies , but the specific experiment has not been replicated. 4,6

What is the criticism of Universe 25?

• The Universe 25 experiment faces several scientific limitations, including experimental biases inherent to observational studies, misinterpretation and unsubstantiated extrapolation to human experiences, and ethical concerns related to animal care . 2-5  

This article was originally published on May 2, 2022.  It was updated on May 28, 2024 by  Deanna MacNeil , PhD .

• Calhoun JB. Population density and social pathology . Scientific American Magazine . 1962;206(2):139. 
• Calhoun JB. Death squared: the explosive growth and demise of a mouse population . Proc R Soc Med . 1973;66(1P2):80-88. 
• Boyko EJ. Observational research opportunities and limitations . J Diabetes Complications . 2013;27(6):642-648. 
• Ramsden E. The urban animal: population density and social pathology in rodent and humans . Bull World Health Organ . 2009;87(2):82.
• Animal Research Advisory Committee (ARAC) Guidelines . OACU. Accessed May 28, 2024.
•  Ramsden E, Adams J. Escaping the laboratory: The rodent experiments of John B. Calhoun and their cultural influence . J Soc Hist . 2009;42(3):761-797. 

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• v.87(2); 2009 Feb

The urban animal: population density and social pathology in rodents and humans

Edmund ramsden.

a School of Humanities and Social Science, University of Exeter, Rennes Drive, Exeter, EX4 4RJ, England.

In a 1962 edition of Scientific American , the ecologist John B Calhoun presented the results of a macabre series of experiments conducted at the National Institute of Mental Health (NIMH). 1 He had placed several rats in a laboratory in a converted barn where – protected from disease and predation and supplied with food, water and bedding – they bred rapidly. The one thing they were lacking was space, a fact that became increasingly problematic as what he liked to describe as his “rat city” and “rodent utopia” teemed with animals. Unwanted social contact occurred with increasing frequency, leading to increased stress and aggression. Following the work of the physiologist, Hans Selye, it seemed that the adrenal system offered the standard binary solution: fight or flight. 2 But in the sealed enclosure, flight was impossible. Violence quickly spiralled out of control. Cannibalism and infanticide followed. Males became hypersexual, pansexual and, an increasing proportion, homosexual. Calhoun called this vortex “a behavioural sink”. Their numbers fell into terminal decline and the population tailed off to extinction. At the experiments’ end, the only animals still alive had survived at an immense psychological cost: asexual and utterly withdrawn, they clustered in a vacant huddled mass. Even when reintroduced to normal rodent communities, these “socially autistic” animals remained isolated until death. In the words of one of Calhoun’s collaborators, rodent “utopia” had descended into “hell”. 3

Calhoun’s experiments with rats and mice proved extremely influential. His findings resonated with a variety of concerns, including population growth, environmental degradation and urban violence. In the course of a project on the history of stress, Jon Adams of the London School of Economics and I have traced how evidence of crowding pathology, generated in the rodent laboratories of NIMH, travelled to an alternative setting: the buildings, institutions and cities of the social scientist, city planner, architect and medical specialist. While urban sociologists and social psychiatrists explored correlations between density and pathologies in their statistical studies, environmental psychologists moved to the laboratory and fields such as the prison, the school and the hospital. Social and medical scientists were attracted to the possibility of providing evidence of how a physical and measurable variable – density – had important consequences demanding policy response. Many had already begun using Calhoun’s rats to support family planning programmes or for improving the physical design of the city. 4

However, results from human studies of crowding proved inconsistent. In an influential series of experiments by the psychologist Jonathan Freedman, individuals employed to carry out tasks under varying conditions of density displayed few pathologies. 5 Focus now shifted away from simply identifying the pathological consequences of density and towards factors that mediated its effects. This was aided by a distinction between “density” as a physical measure and “crowding” as a subjective response. 6 Feeling crowded was determined by a range of social and psychological factors: an individual’s desired level of privacy, their ability to control a situation or their social role. Increased density might be inevitable but human beings were capable of coping with crowding.

Yet this did not mean that Calhoun’s research was rejected. Researchers recognized that Calhoun’s work was not simply about density in a physical sense, as number of individuals-per-square-unit-area, but was about degrees of social interaction. By reducing unwanted interaction through improved design of space – providing prisoners with individual cells or patients with independent living areas – crowding stress could be avoided. 7 This had been the focus of Calhoun’s later research. Through improved design and increased control, Calhoun attempted to develop more collaborative and adaptable rodent communities capable of withstanding greater degrees of density. 8

Continued problems of prison overcrowding and transport congestion ensure that the subject of crowding stress remains pertinent, but the relevance of Calhoun’s experiments is less commonly acknowledged. Towards the end of his career, Calhoun, who died in 1995, would be increasingly dismayed that it was a simplified, negative message – population density equals pathology – that was more commonly associated with his work, making his contribution seem not only flawed in the human context, but dangerous. In the words of the sociologists Fischer & Baldassare: “A red-eyed, sharp-fanged obsession about urban life stalks contemporary thought.” 9 In focusing upon crowding, not only were the benefits of dense city-living ignored, but other causes of urban pathology, such as poverty and inequality, were neglected. Yet Calhoun’s work considered many of these factors, suggested how they could be overcome, and as such, his role deserves reconsideration. ■

September 17, 2024

Book Review: How One Weird Rodent Ecologist Tried to Change the Fate of Humanity

A biography of the scientist whose work led to fears of a ‘population bomb’

By Ben Goldfarb

Frank Stockton

Dr. Calhoun's Mousery: The Strange Tale of a Celebrated Scientist, a Rodent Dystopia, and the Future of Humanity by Lee Alan Dugatkin University of Chicago Press, 2024 ($27.50)

In the 1960s and 1970s American society suffered a yearslong collective panic about the perceived threat of overpopulation. Biologist Paul Ehrlich appeared on The Tonight Show to tout The Population Bomb , his 1968 polemic about human numbers run amok. The 1973 film Soylent Green depicted a squalid hellscape in which surplus people would be processed into food. College students pledged to remain childless for the benefit of Earth.

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This anxiety originated, in part, in the laboratory of John Bumpass Calhoun, an enigmatic ecologist who spent decades documenting the adverse effects of overcrowding on rodents in elaborate experimental “cities.” Calhoun is largely obscure today, but few scientists in his time wielded more influence. He hobnobbed with science-fiction writer Arthur C. Clarke and was featured in books by naturalist E. O. Wilson and journalist Tom Wolfe—in the process spreading overpopulation angst far and wide. “The most profound impact of Calhoun’s studies lies far from academic halls and ivory towers,” writes Lee Alan Dugatkin in Dr. Calhoun’s Mousery , a new biography nearly as quirky as its subject. Calhoun’s work permanently “seeped into the public consciousness.”

Calhoun made for an unlikely prophet. A nature lover from Tennessee, he took a job in the 1940s leading a long-term study in Baltimore with the primary goal of controlling urban rats. Calhoun found that each city block was home to around 150 rats, a number he found low given the “abundant sources of food in open garbage cans.” Rat populations, he suspected, were “self-regulating”: when new rats tried to move in, residents kicked them out. But the unpredictability of Baltimore’s streets—­ where humans were constantly killing rats or messing with the traps—frustrated Calhoun’s analyses. To truly understand rat society, he decided, he needed to control their environment.

In the late 1950s the National Institute of Mental Health gave Calhoun the opportunity to manipulate rats in a remodeled Maryland barn. Calhoun, an endlessly inventive designer of experiments, built an enclosure outfitted with rat apartments and partitioned the pen into connected “neighborhoods,” creating a murid arcadia that he could observe at his leisure.

This utopia soon turned nightmarish. As the rats multiplied, they fed and gathered in ever greater densities, leading to a social breakdown that Calhoun called a “behavioral sink.” Packs of libidinous males relentlessly hounded females, who in turn ignored their offspring; in some neighborhoods, pup mortality hit 96 percent. The rats, Calhoun declared, suffered from “pathological togetherness” that could lead to collapse. In the years that followed, he shifted to mice, but his fundamental conclusions remained the same: rodents succumbed to chaos as their populations exploded.

Calhoun wasn’t shy about extrapolating to our own species’ fate. “Perhaps if population growth continues to grow unchecked in humans, we might one day see the human equivalent” of socially catatonic rodents, he told the Washington Daily News in one characteristic interview. His fears both channeled the zeitgeist and directed it.

Dugatkin—an evolutionary biologist, science historian and prolific author who sifted through thousands of pages at the Calhoun archive in Bethesda—is an admirably thorough researcher. But his granular chronology of Calhoun’s activities sometimes slides too deep into a recitation of media coverage, conference talks and intricate experiments. Amid this blizzard of minutiae, Mousery occasionally loses sight of a question that should be central to any biography: Why does Calhoun matter today? Dugatkin acknowledges that the “lasting impact of [Calhoun’s] work is nowhere near” that of pioneering behaviorists such as Ivan Pavlov. But he misses an opportunity to probe the social debates that his subject’s work catalyzed. Did Calhoun’s darker prognostications do harm? The population bomb, after all, failed to detonate.

Calhoun belonged to a generation of scientists who had no compunctions about straying from their disciplinary lane. He wrote poetry and sci-fi and consulted on humane prison design. Dugatkin captures the grand ambition of a man who gazed at rodents and saw the universe, even if the significance of his research is murky today. As Dugatkin notes, the disturbing dynamics that Calhoun produced in his micromanaged “universes” have never been observed in the wild. Calhoun didn’t describe the world; he created his own.

John B. Calhoun’s Mouse Utopia Experiment and Reflections on the Welfare State

One of the more famous ethologists in recent decades was john b. calhoun, best known for his mouse experiments in the 1960s. to what extent do the mouse utopia lessons apply to humans.

Signs in national and state parks all over America warn visitors, “Please Don’t Feed the Animals.” Some of those government-owned parks provide further explanation, such as “The animals may bite” or “It makes them dependent.”

The National Park Service’s website for Sleeping Bear Dunes in Michigan advises,

It transforms wild and healthy animals into habitual beggars. Studies have shown that panhandling animals have a shorter lifespan. 

What would happen if animals in the wild could count on human sources for their diet and never have to hunt or scrounge? What if, in other words, we humans imposed a generous welfare state on our furry friends? Would the resulting experience offer any lessons for humans who might be subjected to similar conditions? Not having to work for food and shelter sounds appealing and compassionate, doesn’t it?

These are fascinating questions that I am certainly not the first to ask. Because they require knowledge beyond my own, I cannot offer definitive answers. Readers should view what I present here as a prod to thought and discussion and not much more. I report, you decide.

Our personal pets live in a sort of welfare state. Moreover, for the most part, they seem to like it. My two rat terriers get free food and free health care, though I am not only their provider, but I am also their “master” too. In fact, my loving domination is a condition for the free stuff. It seems like a win-win, so maybe a welfare state can work after all. Right?

Let us avoid hasty conclusions. Perhaps the human/pet welfare state works because one of the parties has a brain the size of a golf ball or a pomegranate.

This is an area illuminated by ethology, the scientific study of animal behavior. One of the more famous ethologists in recent decades was John B. Calhoun , best known for his mouse experiments in the 1960s when he worked for the National Institute for Mental Health.

Calhoun enclosed four pairs of mice in a 9 x 4.5-foot metal pen complete with water dispensers, tunnels, food bins and nesting boxes. He provided all the food and water they needed and ensured that no predator could gain access. It was a mouse utopia.

Calhoun’s intent was to observe the effects on the mice of population density, but the experiment produced results that went beyond that. “I shall largely speak of mice, but my thoughts are on man,” he would later write in a comprehensive report.

At first, the mice did well. Their numbers doubled every 55 days. But after 600 days, with enough space to accommodate as many as another 1,600 rodents, the population peaked at 2,200 and began to decline precipitously—straight down to the extinction of the entire colony—in spite of their material needs being met with no effort required on the part of any mouse.

The turning point in this mouse utopia, Calhoun observed, occurred on Day 315 when the first signs appeared of a breakdown in social norms and structure. Aberrations included the following: females abandoning their young; males no longer defending their territory; and both sexes becoming more violent and aggressive. Deviant behavior, sexual and social, mounted with each passing day. The last thousand mice to be born tended to avoid stressful activity and focused their attention increasingly on themselves.

Jan Kubań, a personal friend of mine from Warsaw and a Polish biocybernetician, considers Calhoun’s experiment “one of the most important in human history.” He created The Physics of Life website where he elaborates on the meaning and significance of the ethologist’s work. About the final stages of the mouse utopia, Kubań writes,

Other young mice growing into adulthood exhibited an even different type of behavior. Dr. Calhoun called these individuals “the beautiful ones.” Their time was devoted solely to grooming, eating and sleeping. They never involved themselves with others, engaged in sex, nor would they fight. All appeared [outwardly] as a beautiful exhibit of the species with keen, alert eyes and a healthy, well-kept body. These mice, however, could not cope with unusual stimuli. Though they looked inquisitive, they were in fact, very stupid.

Because of the externally provided abundance of water and food, combined with zero threats from any predators, the mice never had to acquire resources on their own. The young mice never observed such actions and never learned them. The life skills necessary for survival faded away. As Kubań notes,

Utopia (when one has everything, at any moment, for no expenditure) prompts declines in responsibility, effectiveness and awareness of social dependence and finally, as Dr. Calhoun’s study showed, leads to self-extinction.

The “behavioral sink” of self-destructive conduct in Calhoun’s experiment (which he replicated on numerous subsequent occasions) has since been mostly interpreted as resulting from crowded conditions. Demographers warn that humans might succumb to similar aberrations if world population should ever exceed some imaginary, optimal “maximum.” Others like Kubań point out that the mice utopia fell apart well before the mouse enclosure was full. Even at the peak of the population, some 20 percent of nesting beds were unoccupied.

My instincts tell me that Kubań is correct in suggesting that a more likely culprit in the mice demise was this: the lack of a healthy challenge . Take away the motivation to overcome obstacles—notably, the challenge of providing for oneself and family—and you deprive individuals of an important stimulus that would otherwise encourage learning what works and what doesn’t, and possibly even pride in accomplishment (if mice are even capable of such a sentiment). Maybe, just maybe, personal growth in each mouse was inhibited by the welfare-state conditions in which they lived.

Calhoun himself suggested a parallel to humanity:

Herein is the paradox of a life without work or conflict. When all sense of  necessity is stripped from the life of an individual, life ceases to have purpose. The individual dies in spirit.

By relieving individuals of challenges, which then deprives them of purpose, the welfare state is an utterly unnatural and anti-social contrivance. In the mouse experiment, the individuals ultimately lost interest in the things that perpetuate the species. They self-isolated, over-indulged themselves, or turned to violence.

Does that ring a bell? Read Charles Murray’s 1984 book, Losing Ground , or George Gilder’s earlier work, Wealth and Poverty , and I guarantee that you will hear that bell.

Or, if nothing else, ponder these prophetic words from one of the otherwise short-sighted, opportunistic architects of the American welfare state, Franklin Delano Roosevelt, in 1935:

The lessons of history, confirmed by the evidence immediately before me, show conclusively that continued dependence upon relief induces a spiritual and moral disintegration fundamentally destructive to the national fiber. To dole out relief in this way is to administer a narcotic, a subtle destroyer of the human spirit.

I can think of one big difference between Calhoun’s mouse utopia and the human welfare state, and it does not weigh in humanity’s favor. For the mice, everything truly was “free.” No mouse was taxed so another mouse could benefit. In the human welfare state, however, one human’s benefit is a cost to another (or to many)—a fact that rarely acts as an incentive for work, savings, investment, or other positive behaviors. That suggests that a human welfare state with its seductive subsidies for some and punishing taxes for others delivers a double blow not present in mouse welfarism.

To what extent do the mouse utopia lessons apply to we humans? I would be careful about drawing sweeping conclusions. I am reminded, however, of these words from economist Thomas Sowell: “The welfare state shields people from the consequences of their own mistakes, allowing irresponsibility to continue and to flourish among ever wider circles of people.”

We should not need mice or other animals to teach us that, but perhaps they can.

For additional information, see:

John Calhoun’s Experiment , by Jan Kubań

The Mouse Utopia Experiments: Down the Rabbit Hole (video)

The War on Poverty Wasn’t a Failure—It Was a Catastrophe , by Louis Woodhill

Thomas Sowell on the Legacy of the Welfare State , (video)

12 Reasons to Oppose the Welfare State , by Bryan Caplan

More By Lawrence W. Reed

Albert Gallatin and Jefferson’s Embargo

Do You Know the Ten Cannots?

Albert Gallatin, the Amazing Swiss-American

Two Polish Heroes Every American Should Know

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Universe 25: The Mouse "Utopia" Experiment That Turned Into An Apocalypse

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The utopia in all its glory. Image credit: Yoichi R Okamoto, White House photographer (public domain, via Wikimedia Commons ).

Over the last few hundred years, the human population of Earth has seen an increase, taking us from an estimated one billion in 1804 to seven billion in 2017. Throughout this time, concerns have been raised that our numbers may outgrow our ability to produce food, leading to widespread famine. 

Some –  the Malthusians  – even took the view that as resources ran out, the population would "control" itself through mass deaths until a sustainable population was reached. As it happens, advances in farming, changes in farming practices, and new farming technology have given us enough food to feed  10 billion people , and it's how the food is distributed which has caused mass famines and starvation. As we use our resources and the climate crisis worsens, this could all change  – but for now, we have always been able to produce more food than we need, even if we have lacked the will or ability to distribute it to those that need it.

But while everyone was worried about a lack of resources, one behavioral researcher in the 1970s sought to answer a different question: what happens to society if all our appetites are catered for, and all our needs are met? The answer – according to his study – was an awful lot of cannibalism shortly followed by an apocalypse.

John B Calhoun set about creating a series of experiments that would essentially cater to every need of rodents, and then track the effect on the population over time. The most infamous of the experiments was named, quite dramatically, Universe 25 .

In this study, he took four breeding pairs of mice and placed them inside a "utopia". The environment was designed to eliminate problems that would lead to mortality in the wild. They could access limitless food via 16 food hoppers, accessed via tunnels, which would feed up to 25 mice at a time, as well as water bottles just above. Nesting material was provided. The weather was kept at 68°F (20°C), which for those of you who aren't mice is the perfect mouse temperature. The mice were chosen for their health, obtained from the National Institutes of Health breeding colony. Extreme precautions were taken to stop any disease from entering the universe.

As well as this, no predators were present in the utopia, which sort of stands to reason. It's not often something is described as a "utopia, but also there were lions there picking us all off one by one". 

The experiment began, and as you'd expect, the mice used the time that would usually be wasted in foraging for food and shelter for having excessive amounts of sexual intercourse. About every 55 days, the population doubled as the mice filled the most desirable space within the pen, where access to the food tunnels was of ease.

When the population hit 620, that slowed to doubling around every 145 days, as the mouse society began to hit problems. The mice split off into groups, and those that could not find a role in these groups found themselves with nowhere to go.

"In the normal course of events in a natural ecological setting somewhat more young survive to maturity than are necessary to replace their dying or senescent established associates," Calhoun wrote in 1972 . "The excess that find no social niches emigrate."

Here, the "excess" could not emigrate, for there was nowhere else to go. The mice that found themself with no social role to fill – there are only so many head mouse roles, and the utopia was in no need of a Ratatouille -esque chef – became isolated.

"Males who failed withdrew physically and psychologically; they became very inactive and aggregated in large pools near the center of the floor of the universe. From this point on they no longer initiated interaction with their established associates, nor did their behavior elicit attack by territorial males," read the paper. "Even so, they became characterized by many wounds and much scar tissue as a result of attacks by other withdrawn males."

The withdrawn males would not respond during attacks, lying there immobile. Later on, they would attack others in the same pattern. The female counterparts of these isolated males withdrew as well. Some mice spent their days preening themselves, shunning mating, and never engaging in fighting. Due to this they had excellent fur coats, and were dubbed, somewhat disconcertingly, the "beautiful ones".

The breakdown of usual mouse behavior wasn't just limited to the outsiders. The "alpha male" mice became extremely aggressive, attacking others with no motivation or gain for themselves, and regularly raped both males and females . Violent encounters sometimes ended in mouse-on-mouse cannibalism.

Despite – or perhaps because – their every need was being catered for, mothers would abandon their young or merely just forget about them entirely, leaving them to fend for themselves. The mother mice also became aggressive towards trespassers to their nests, with males that would normally fill this role banished to other parts of the utopia. This aggression spilled over, and the mothers would regularly kill their young. Infant mortality in some territories of the utopia reached 90 percent.

This was all during the first phase of the downfall of the "utopia". In the phase Calhoun termed the "second death", whatever young mice survived the attacks from their mothers and others would grow up around these unusual mouse behaviors. As a result, they never learned usual mice behaviors and many showed little or no interest in mating, preferring to eat and preen themselves, alone.

The population peaked at 2,200 – short of the actual 3,000-mouse capacity of the "universe" – and from there came the decline. Many of the mice weren't interested in breeding and retired to the upper decks of the enclosure, while the others formed into violent gangs below, which would regularly attack and cannibalize other groups as well as their own. The low birth rate and high infant mortality combined with the violence, and soon the entire colony was extinct . During the mousepocalypse, food remained ample, and their every need completely met.

Calhoun termed what he saw as the cause of the collapse "behavioral sink".

"For an animal so simple as a mouse, the most complex behaviors involve the interrelated set of courtship, maternal care, territorial defence and hierarchical intragroup and intergroup social organization," he concluded in his study.

"When behaviors related to these functions fail to mature, there is no development of social organization and no reproduction. As in the case of my study reported above, all members of the population will age and eventually die. The species will die out."

He believed that the mouse experiment may also apply to humans, and warned of a day where – god forbid – all our needs are met.

"For an animal so complex as man, there is no logical reason why a comparable sequence of events should not also lead to species extinction. If opportunities for role fulfilment fall far short of the demand by those capable of filling roles, and having expectancies to do so, only violence and disruption of social organization can follow."

At the time, the experiment and conclusion became quite popular, resonating with people's feelings about overcrowding in urban areas leading to "moral decay"  (though of course, this ignores so many factors such as poverty and prejudice).

However, in recent times, people have questioned whether the experiment could really be applied so simply to humans – and whether it really showed what we believed it did in the first place.

The end of the mouse utopia could have arisen "not from density, but from excessive social interaction," medical historian Edmund Ramsden said in 2008 . “Not all of Calhoun’s rats had gone berserk. Those who managed to control space led relatively normal lives.”

As well as this, the experiment design has been criticized for creating not an overpopulation problem, but rather a scenario where the more aggressive mice were able to control the territory and isolate everyone else. Much like with food production in the real world, it's possible that the problem wasn't of adequate resources, but how those resources are controlled.

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What the Rat City Experiments Mean for Society

In a utopia where all our needs are met, what could possibly go wrong.

Introduction

From the 1940s, John Calhoun conducted a series of experiments on rodents to study behaviour during overcrowding. He created enclosed spaces called "rat utopias" for rats to live in with no predators and minimal exposure to disease. These spaces were designed to cater to every need of the rodents. One of the most famous experiments in psychology and sociology, Calhoun's Mouse Utopia experiments in the 1960s and 1970s, aimed to investigate overpopulation in rodent communities and find a rat utopia. Despite having unlimited access to food and water, personal space was essential to prevent societal collapse, as a series of rodent experiments showed. This article will explore Calhoun's mouse utopia experiments, while also discussing Durkeim's theories, proximics alone, space, and density.

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Calhoun’s Mouse and Rat experiments

Calhoun's experiments gripped a society consumed by fears of overpopulation and his findings resonated with concerns around population growth. In his ultimate research experiment, Universe 25, a population of mice grew within a limited space, leading to a mouse paradise that eventually turned into a dystopia due to overcrowding.

At first, the mive lived out peaceful days, but after months of confined space and a rising population, this began to change. Numerous female rats experienced difficulties in carrying pregnancies to full term or surviving the delivery of their litters. A significant number of those who successfully gave birth refuted their young’s needs. Among the male rats, their behavioural disruptions encompassed sexual deviation, cannibalism, frenetic overactivity, and a pathological withdrawal. These individuals would only emerge to eat, drink, and move about when the rest of the community was asleep. The disruption extended to the social organization of the animals.

The root cause of these disturbances became strikingly evident in the initial series of three experiments, wherein we observed the emergence of what was termed a 'behavioural sink.' The rats would congregate in large numbers within one of the four interconnected pens that housed the colony. During feeding periods, up to 60 out of 80 rats in each experimental population would gather in a single pen. Individual rats seldom ate alone, leading to a proliferation of population density within the pen designated for feeding, while the others remained sparsely populated. In the experiments in which the behavioural sink developed, infant mortality ran as high as 96 percent among the most disoriented groups in the population. Two distinct types of males emerged, each having withdrawn completely from the struggle for dominance. However, they differed greatly in terms of their activity levels. The first group exhibited absolute passivity and moved through the community like sleepwalkers. They paid no attention to other rats, irrespective of gender, and likewise went unnoticed by their peers. Even during the females' estrus period, these passive individuals made no attempts to approach them. Rarely did other males engage in aggression or attempt to interact with them. Superficially, these passive animals would appear to be the healthiest and most appealing members of the community, boasting plumpness and a sleek coat devoid of the typical marks and bald patches caused by male combat. However, they were essentially walking in a coma-like state.

The other category of males were a the opposite end of the spectrum from the passive males. They exhibited a frenzied and hyperactive behavior within the community. Their relentless energy seemed boundless as they engaged in various activities. These highly active males sought dominance and engaged in frequent bouts of play and aggression with other usually male rats. They actively pursued females during their estrus, often initiating advances towards them. These males rarely experienced attacks or resistance from other males due to their vigorous and dominant nature. Although their appearance may not have been as pristine as the passive males, with occasional signs of physical wear from their active engagement, their social orientation remained intact."

The question most of the public had when confronted with this observation was, how does this apply to humans in confined, over-crowded environments? How might this impact life as a human in a modern city?

Durkheim on mental health in over-crowded environments

Emile Durkheim's exploration of suicide forms a compelling argument that the social organization and religion inherent in modern industrial societies play a substantial role in mental health. Delving into the intricacies of different forms of suicide, Durkheim posits that our understanding of mental health cannot be disentangled from the societal structures we inhabit. He concludes that these social constructs act as determinants of mental health, a perspective that remains influential in the field of sociology to this day.

Proximics and broader considerations Proximics, or the study of space and distance in communication and behaviour, is an area of interest in sociology. The conceptual model presented in the book "Social Network Analysis" suggests that our social networks hold a powerful influence over our health, mental health, and health behaviours. It concludes that the analysis of these networks can provide profound insights into individual and community health, shifting the traditional views on the impact of social connections. It is interesting to observe that religious people often outlive non-religious ones, due to the inherent nature of a community, a tight circle for people to take care of one another and minimize the number of external threats together.

The field of mental health presents an array of resources that argue for a more nuanced and multidimensional approach to understanding mental health issues. The book "Malpractice: A Guide for Mental Health Professionals," coupled with tools like the Occupational Case Analysis Interview and Rating Scale, posits that professionals can better serve their patients through a comprehensive understanding of the sociological aspects of mental health. The conclusion is a call for a more integrated approach to mental health care, where sociology and psychology interact seamlessly.

Finally, Professor Ritzer's contributions to metatheory and applied social theory present a persuasive argument for the value of novel perspectives in understanding societal phenomena. His work argues for the necessity of continual theory development and evolution, prompting sociologists to challenge and expand upon existing frameworks. The conclusion drawn is that the field of sociology must remain dynamic, open to fresh insights and deeper understandings.

This exploration of Calhoun's Mouse Utopia experiments, Durkheim's theories, and proximics underscores the profound effects of overcrowding and limited personal space on societal stability. Drawing parallels to human societies, particularly in confined, overcrowded urban environments, these studies underscore the potential for analogous effects on mental health, altering societal structures, and social behaviour. The need for a multidimensional approach integrating sociology and psychology in understanding mental health is clear, as it allows for a holistic view of mental health issues and better service provision by professionals. This discussion serves as a reminder of the interconnectedness of physical, social, and mental health, and the shaping role our environments play in these aspects of life.

https://fee.org/articles/john-b-calhoun-s-mouse-utopia-experiment-and-reflections-on-the-welfare-state/

https://www.sciencehistory.org/distillations/mouse-heaven-or-mouse-hell

https://www.victorpest.com/articles/what-humans-can-learn-from-calhouns-rodent-utopia

https://www.smithsonianmag.com/smart-news/how-mouse-utopias-1960s-led-grim-predictions-humans-180954423/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4339207/

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