Mar 05, 2015 I Brent Swancer

The Amazing Rise and Fall of a Rodent Utopia

Human beings seem to have a tendency to take our society for granted. We expect that rules will be followed and that the comfortable world around us will continue to run smoothly as it always has. Even as the populations of major cities around the world soar, we trust that society will stand strong under the weight of so many souls and guide us towards a prosperous future. Those who lead comfortable lives become complacent, confident in their place in the world, their purpose, and their legacy. What many do not understand is just how thin a thread the balance of society often teeters upon and just how close the tipping point may loom. In 1972, one animal behaviorist by the name of John Calhoun got a frightening glimpse of what potential mayhem lurks behind the shiny veneer of our civilized society when he created a utopian paradise for rats that spectacularly disintegrated before his eyes, and shone a light on the dark forces that influence us at the basest levels.

John Calhoun was an ethologist and animal behaviorist who had had a long standing interest in how rodents interact and create societies. Starting in 1947, Calhoun began experimenting with rats and mice on a rural property in Rockville, Maryland in order to investigate the behavioral effects on the animals when provided with unlimited food and resources; essentially a rodent paradise. One of his main interests was the potential effects of overcrowding on human society and behavior, which was seen as a very real potential problem in the post-war 1940s, where worldwide populations were growing rapidly. In his early experiments, Calhoun observed a colony of Norway rats for 28 months, during which time he provided the animals with as much food as they needed as well as total safety from predators. It was expected that the population would skyrocket uncontrollably to around 5,000 animals during this period of time, however, the population oddly never went past 200. He also noticed that the colony split into smaller, separate groups of no more than 12 individuals per group.

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John B. Calhoun - ethologist and behavioral researcher

Intrigued by these results, Calhoun continued his work with rats and mice, and finally in 1958 he created his own lab in the second floor of a barn from which to launch his most ambitious series of experiments yet, which consisted of creating a series of what he called “Universes” which were habitats designed to be rodent utopias, free of disease, predators, and providing unlimited resources. In each instance, the rodent populations experienced a rapid rise in population followed by a levelling off that seemed to go hand in hand with a variety of unusual, deviant behaviors, before finally the birthrate screeched to a halt, after which the rodent society would implode and cease to exist.

Calhoun would write a prominent paper on the experiments in 1962 called Population density and social pathology, which was published in Scientific American and outlined his observations of the effects of overcrowding on rodent behavior. In the paper, he coined the term “behavioral sink,” which referred to societal collapse in the face of behavioral degradation and signifying a point of no return leading to extinction marked by a reversion to deviant acts caused by overcrowding. The paper would put the sobering potential effects of overpopulation into the public consciousness and people were already comparing the findings made in these early experiments to human society. This paper became incredibly influential in the field of psychology and is still heavily referenced to this day.

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A schematic of one of Calhoun's early experiments.

These experiments culminated in Calhoun’s most famous and ambitious experiment of them all, “Universe 25.” Calhoun created a complex, controlled environment that was a large room that measured 2.7 meters square and was split into 4 separate interconnected pens. Surrounding this Universe were 16 tunnels leading to food, water, and various burrows, and there was a total of 256 "apartments," each able to accommodate up to 15 mice, all connected for easy access by a series of ramps. Four breeding pairs of mice were introduced to this spacious enclosure and were given unlimited, easy access to food and water. This sort of habitat was referred to as a “mortality-inhibiting environment,” basically with the aim of limiting transmittable diseases, providing limitless food, water, nesting material, and other valuable resources, and basically doing everything possible to make sure the rats didn’t die or face any real discomfort; in essence emulating the conditions of many humans in similar environments. The temperature was kept at a constant, balmy 20 degrees Celsius or more, and the mice had free reign to roam wherever they liked within the habitat. Throughout the whole experiment the enclosure would be kept clean and disease free, with the health of the mice constantly monitored by veterinarians. The only limitation faced by the mice would be that of physical space. Then Calhoun sat back and waited to see what would happen.

The rodents first spent around 104 days getting accustomed to their environment, a phase that Calhoun referred to as the “strive period,” or an initial period of adjustment when the mice were basically just establishing territories and creating nests. Then the mouse population at first began to increase at a rapid rate just as predicted, a phase that was called the "exploit period.” During this phase, the mouse population of Universe 25 roughly doubled every 55 days until by day 315 their numbers had reached 620. At this point, the large enclosure was becoming a bit crowded in some places and the birthrate plunged to a much lower rate, about one third of what it had been before. It was also noticed that food was being consumed more in certain areas, despite the fact that all of the compartments were identical. The mice began to associate eating and drinking with being with others, rarely if ever eating alone, and the population started to gravitate towards certain compartments where all of the eating took place. This made some apartments and compartments crowded well beyond their intended capacity while others remained sparsely populated or even empty. The enclosure wasn’t truly overcrowded, as it had been designed for up to 3,000 mice, but rather, it had developed a very unbalanced distribution of individuals. This persistent gathering and eating in overcrowded gathering points seemed to result in three times more socially immature mice than socially established ones, suggesting that they were somehow losing their ability to form social bonds. That was around the time when the perfect society of unlimited resources that Calhoun had so meticulously created began to crumble.

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Universe 25

From around Day 315 of the experiment, a wide variety of odd behavior started to surface among the animals. Some male mice who had no social role in the face of the burgeoning population suddenly seemed to lose their sense of purpose and became detached from these natural roles. They stopped trying to defend their own territory or pregnant females, lost interest in those around them, and whereas they would normally emigrate to other broods they found none willing to accept them and so became listless wanderers tending to congregate in the center of the Universe where they spent their days mindlessly eating or fighting amongst themselves. These males were seen as the "outcasts" of the society. The more dominant males among these became markedly more vicious and violent, attacking others without provocation and fighting for no apparent reason. Many of these roving males would roam about attacking or mounting, essentially raping, other mice indiscriminately, regardless of gender or relation. The non-dominant males conversely became extremely meek and passive, with some of them becoming the targets of repeated attacks by other males while refusing to fight back. In some cases, cannibalism occurred among the mice, and there was generally a descent into feral, violent behavior punctuated by intense bursts of shocking brutality.

The female mice were not having much more luck. In the absence of any males willing to protect their nests, mothers began to become highly aggressive towards trespassers, essentially taking on the role typically reserved for the males. Unfortunately, this went into overdrive. Young mice were banished before they were weaned and often mothers ignored their young or seemingly forgot about them. Some females became unusually aggressive towards even their own offspring and would even sometimes attack and kill their own young, while others became morose hermits who refused to mate. All of this led to a quickly sinking birthrate and an infant mortality rate of over 90% in some areas of the enclosure. This era of bursts of explosive violence and hypersexual behavior came to be known as the “stagnation phase,” or “equilibrium period.” Calhoun speculated that a lack of social roles to fill combined with constant, unwanted social and physical contact in the face of the increased population density was at the root of the aggression, withdrawal, and sexual deviancy.

The final phase of the experiment was ominously referred to as “the death phase” or “die period.” By Day 560, the population increase had plunged to next to nothing, partly due to the alarming mortality rate that had reached nearly 100% and partly due to a disinterested attitude towards procreation that began to be exhibited in many of the male mice.  Amid all of this turmoil and degradation within Universe 25, there was also a new generation of mice emerging that had not ever been subjected to a normal social upbringing and showed absolutely no interest in fighting, courtship, mating, raising young, or much of anything really. Calhoun referred to this aberrant group of mice as “the beautiful ones.” These “beautiful ones” were completely detached from society, had completely lost touch with normal mouse behavior, and spent all of their time eating, sleeping, or incessantly grooming and preening themselves, leading them to having a fine, robust, healthy appearance with keen and alert eyes, hence their name. Calhoun often referred to these mice as “handsome,” however, their beauty was truly only skin deep. Inside they were empty. The beautiful ones lived peacefully secluded and withdrawn from the rest of the society in the less crowded areas; eating, sleeping, avoiding conflict, grooming, and not mating in any way, and seemed to be spared any violence that broke out among the other mice, yet they did nothing to further the society either. They had essentially lost all of their desire to interact with others and spent their days in a lackadaisical daze.

Calhoun liked to refer to this drastic detachment and lack of will to participate in society as the “first death,” or basically the death of the animal’s spirit, which would occur before the “second death,” or physical death of the body. Once this “first death” was reached, the mice were no longer really mice anymore but rather empty husks merely killing time awaiting the inevitable death of their body and an end to their pointless existence. They had in a sense lost all will to live in any useful manner.

Calhoun would later muse on the reasons behind the rise of these “beautiful ones,” these mice which were healthy in appearance yet had died in spirit. He theorized that mice were in many respects like mankind, and that in the absence of any tension, pressure, or stress they had lost their focus and sense of purpose and identity. With an overabundance of vital resources and no need to do anything to obtain them, the need for societal roles or jobs had faded, leaving the mice in a state of being unable and/or unwilling to perform all but the most basic functions of sustaining physiological life such as eating and sleeping. In essence, the thinking was that these mice, and indeed it could be inferred human beings as well, required conditions of stress, pressure, obstacles, and a clear purpose in order to have a destiny and a desire to engage in society.


With the majority of mice becoming those who refused to mate, engage others, or indeed perform any useful societal functions at all, the population increase of Universe 25 ceased altogether, with the last conception recorded at Day 920. By this time the population had reached its peak of 2,200 individuals, which was somewhat crowded but still well under the enclosure’s maximum capacity of 3,000. With zero population increase, a shocking mortality rate, and a majority population now completely disinterested in procreation and living on the upper levels of the enclosure in seclusion, the rest of the remaining mice were still forming marauding gangs, congregating into crowded areas and devolving into a morass of endemic violence and cannibalism, with many of them completely missing tails or exhibiting brutal battle scars. Bear in mind that even at this turbulent point in time, the mice still had free access to all of the food and resources they could ever need. This was the unstoppable slide to catastrophe, the point of no return, the “behavioral sink” that Calhoun had talked about, and the mouse utopia’s apocalypse came crashing down as all of these factors conspired to cause the population to start barrelling rapidly towards extinction until there were none left. Universe 25 hd ceased to exist.

Calhoun was alarmed by the spectacular descent into ruin of the colony, and before the apocalyptic end of the “death phase,” he removed a few of the “beautiful ones” for the purpose of seeing if they could reintegrate into a mouse society under different conditions. A few small groups of these “beautiful ones” were removed from Universe 25 and placed in equally ideal conditions, yet with a small population and unlimited space. They were essentially placed in more or less the same conditions that had been faced by the original breeding pairs of Universe 25, and it was expected they would snap out of their daze and begin populating the new habitat, in essence rebuilding society. Calhoun and associates were somewhat taken aback when the displayed absolutely no change in their previous behavior. They continued to show a complete disinterest in social interactions or reproduction, and refused to mate, which led to no new births in the new habitat whatsoever. In the end, this small group of mice died of old age, having never shown the slightest interest in repopulating or rebuilding their society, despite living in ideal conditions. Calhoun would conclude his study on an ominous note, saying:

For an animal so simple as a mouse, the most complex behaviors involve the interrelated set of courtship, maternal care, territorial defense and hierarchical intragroup and intergroup social organization. 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 or the population will age and eventually die. The species will die out. 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 expectations to do so, 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. Just as biological generativity in the mouse involves this species' most complex behaviors, so does ideational generativity for man. Loss of these respective complex behaviors means death of the species.

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Calhoun and his mice

Calhoun’s findings and observations on Universe 25 were published in the rather spookily titled paper Death Squared: The Explosive Growth and Demise of a Mouse Population, which immediately shot into the public consciousness and became at once controversial and a sobering look into what could happen to humans as well. It was also widely misinterpreted and misunderstood. The public mostly took the findings in a negative way, and with the country as it was at the time why wouldn’t they? After all, the Universe 25 study was done at a time when the population was soaring, urbanization was burgeoning, and at around the same time as incidences of urban violence such as the Watts Riots in 1965 and widespread civil unrest across the country in in the wake of the Martin Luther King Jr. assassination in 1968. Everywhere one turned it seemed that there was some riot, mass panic, outbreak of violence, or other signs of an imminent breakdown of social order stemming from the crowd, and Calhoun’s study of Universe 25 seemed to eerily mirror the world that seemed to be unravelling around them.

The study seemed to confirm the public’s darkest fears; that society had reached a tipping point towards disaster and that overcrowding directly equated to doom and degeneracy, nihilism and inevitable collapse. In certainly didn’t help matters that various books and movies were being released at the time that approached this topic in a negative way, such as Soylent Green in 1973, which depicts an overpopulated society unknowingly being fed the remains of the dead, as well as the book A Clockwork Orange in the 60s with its roving gangs of directionless, ultraviolent hooligans, among many others. In light of all of this, Calhoun’s paper became a dire warning, an omen even, of things to come and fueled a particular bleak, pessimistic public attitude.

Yet for all of this apocalyptic talk of looming societal collapse and Calhoun’s own somber, portentous wording, he in fact did not really intend to prove that overcrowding and lack of social roles would irreversibly lead to the inevitable downfall of mankind. Certainly Calhoun saw his mice as a social, psychological and physiological model for humankind, and his liberal use of anthropomorphic terminology such as “apartments,” “tower blocks,” “dropouts,” “juvenile delinquents,” and “beautiful ones” reflected that, but his real intentions were actually more positive than they seemed to most who had read his work. Although he saw the fate of his mice as a metaphor for the potential fate of humankind, Calhoun was more interested in how human beings had the power to reverse this trend; to heal, and to overcome the type of spiraling collapse that had befallen Universe 25. He even famously said himself:

I shall largely speak of mice, but my thoughts are on man, on healing, on life and its evolution. Threatening life and evolution are the two deaths, death of the spirit and death of the body.

Calhoun was dismayed that his work had been embraced by the portion of society that saw nothing but hopelessness in store for mankind, yet he tried to clarify his intent and put a positive spin on it. He was quick to point out that Universe 25, with its unlimited infinite resources in a limited space, was a decidedly unnatural environment and that it did not necessarily reflect the reality that we were faced with. He further theorized that mankind had averted a similar catastrophe because, unlike the mice, we have a different psychological sense of space and exhibit an understanding of what he called “conceptual space,” which meant that we are able to utilize ideas for the purpose of mining resources and guiding social interactions. In short, he believed that mankind’s self-awareness and knack for creativity and design could solve our problems and help us avoid the fate of the mice of Universe 25. Calhoun had even observed this among the mice to some extent, noting that the ones that had become resourceful and creative, as well as those more able to handle social interactions, had been the ones most likely to survive the world crumbling around them. In spite of the negative connotations related to his work, Calhoun remained hopeful that mankind could utilize our innovation, creativity, imagination, and positivity to overcome our limitations. However, not everything was a cheerful, sunny vision of the future.

For all of his optimism for the future and faith in mankind’s ability to change it, Calhoun still warned that in spite of our sophistication and intelligence as a species, we still faced grave danger if we did nothing to change the way our cities operated. He still insisted that human society would face explosive collapse once the number of people capable of filling societal roles dramatically exceeded the number of roles available. The behavioral sink still loomed threateningly over us, and Calhoun maintained that once humanity had reached this event horizon, pathological behavior and deviancy would spiral out of control and we would have reached a tipping point from which there would be no return, just as had happened with the mice of Universe 25. If we reached that point, he theorized, we were doomed.


In order to avoid that doom, Calhoun continued his work well after the fall of Universe 25 with the intent of finding ways to minimize the negative effects of overcrowding and simultaneously maximize creativity. One of his more unusual ideas was to promote space colonization to advance our society, even going so far as to organize a multidisciplinary group called the Space Cadets to research and advocate this, but he also focused closer to home. There was the strong belief that the way we lived could be profoundly impacted by the way cities were designed.  He wanted to find ways to creatively change our behaviors and how our cities were designed in order to promote innovation and positive interaction between us, and to prevent stagnation so that we would not reach that dreaded behavioral sink that would spell our certain extinction. To this end, Calhoun would go on to create over 100 additional rodent Universes and his work would become influential in city planning philosophies all over the world.

So where does this leave us as a species? In modern times more than half of the Earth’s population is packed into ever growing, ever more crowded cities. Is our rapidly urbanized society really as unshakeable and stable as we like to think it is? Are we experiencing the same effects that befell Universe 25 and if so, which phase are we at? If we do not change how we think about each other, our surroundings, and the way we live are we going to emerge unscathed or are we already firmly into the rut that will send us careening past the point of no return to a dismal end? Is it already too late? No matter how much stock one puts into Calhoun’s findings and how they relate to human society, the rise of the utopia of Universe 25 and its spectacular descent into hell certainly seems worth pondering. As the world population hurtles towards an estimated 9.6 billion people by 2050, it seems that there are perhaps some profound messages on the nature of our society and psyche to be found here that may help us come to an understanding of how safe we really are and what we can do to improve our world.

Brent Swancer

Brent Swancer is an author and crypto expert living in Japan. Biology, nature, and cryptozoology still remain Brent Swancer’s first intellectual loves. He's written articles for MU and Daily Grail and has been a guest on Coast to Coast AM and Binnal of America.

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