In 1968, John B. Calhoun, an American ethologist, and behavioral researcher, created the Universe 25 Project. For this study, he built a mice utopia purposefully designed to provide the mice with everything they needed and satisfy their every whim.
In essence, he created a perfect society of mice to study their behavior and see if they would thrive. Spoiler alert: they didn’t. But why? And what does that mean for humans? Well, that is exactly the point of this article today.
Calhoun’s Early Experiments
Calhoun dedicated his entire career to the study of population density and its effects on behavior. He was focused on the problem of crowding, which led him to conduct a series of experiments and studies using rats and mice as subjects.
His experimental research started in 1947. That year, he started a 28-month study of a colony of Norway rats at Johns Hopkins University. The colony of Norway rats was enclosed in a 10,000 square-foot outdoor pen, where they were supplied with unlimited water and food.
The rat population was expected to reach 5,000 over the course of the experiment; however, the population never grew beyond 200 and it stabilized at 150. During the study, the rats subdivided themselves into small groups of up to 12 individuals.
Calhoun noted that 12 was the maximum number of rats that could live in harmony; anything beyond that would lead to stress and psychological effects causing the group to break.
This confirmed Calhoun’s central contention that there is a limit to the number of meaningful interactions individuals can cope with before stress enters the picture. So, as the rat population increased, it became difficult for individuals to control how often they had social contact.
That lead to unwanted interaction, which made them hostile and withdrawn. Ultimately, this caused a psychological breakdown and the rat society would collapse and they would become extinct.
He continued studying rats throughout the 1950s, building more complex enclosures for the rats to examine how they would behave in an environment where they never lacked food and water, and that was predator-free. All the experiments would lead to the same sequence of events:
- At first, the mice would meet, mate, and breed abundantly.
- Then, the society would reach a leveling-off point.
- After that, the mice would either become hostile or form cliques or passive and anti-social.
- Eventually, they would become extinct.
The Introduction of Behavioral Sink
In 1962, Calhoun wrote about his research in an article for the Scientific American called “Population Density and Social Pathology.” In this article, he coined the term “behavior sink” to describe the breakdown of social functions and population collapse that stemmed from overcrowding in his rodent enclosures.
Calhoun described this behavioral sink as a kind of para-pathology that appears from, and succeeds upon, the behavior of individual animals within a group. In other words, the behavioral sink would emerge from erratic behavior and then act as an accelerant of other pathological behaviors. Essentially, it would exacerbate all kinds of pathology present in a group, thus making crowding lethal.
This publication was met by a receptive audience and the period that followed would see a surge of movies, books, and even comics that would depict an apocalyptic view of the future as a result of over-population, undoubtedly influenced by Calhoun’s findings.
It is important to note that behavioral sink could be avoided by altering feeding arrangements to reduce social contact. When the behavioral sink was prevented, Calhoun found that crowding became less lethal, but it was still not ideal by any means.
The Universe 25 Project
Expanding on earlier studies, Calhoun created his ultimate research experiment, dubbed Universe 25. For this one, he used mice and he built a tank that was 101 inches square, enclosed by walls that were 54-inch high. Every wall featured 16 vertical mesh tunnels which can be called stairwells.
Four horizontal corridors opened from each stairwell, leading to 4 rooms. In total, there were 256 rooms, or “nesting boxes” as Calhoun called them, that could house 15 mice each. There were also 16 burrows leading to unlimited food and water.
According to Calhoun’s calculations, the enclosure could reliably and comfortably house up to 3,840 mice. The environment was plague-free, predator-free, and specifically designed so the mice would not lack anything at all.
For the experiment, Calhoun decided on 4 breeding pairs of mice that were specifically bred for Universe 25. These specimens were hand-picked to make sure they were the healthiest ones and they were provided by the National Institute of Health.
The Course of the Experiment
The specimens were released into the enclosure so they could start their society and the evolution of this mice utopia was categorized in a series of phases. Phase A marked the initial period of adjustment, Phase B marked the beginning of population growth, Phase C marked the final period of population growth, and Phase D marked the decline and extinction of the population.
During Phase A and B, the experiment seemed quite promising. Phase C took a sour turn, though. At this point, the population increased tremendously, which reduced the availability of meaningful societal roles. Helpless males became inactive and separated themselves from the rest in large pools located near the center of the universe’s floor. They no longer interacted with others.
Though territorial males didn’t attack these social rejects, so to speak, violence was still prominent, leading the dominant males to lose their ability to defend the females. This led to nest invasions and infant mortality.
Mice born during Phase C didn’t experience normal social interactions, so they didn’t develop the skills to court, care for infants, or defend their territory. You can imagine how detrimental that was to their development.
By the time Phase D rolled around, there were no young and the mice who survived couldn’t conceive or simply didn’t want to. Eventually, that led to their extinction.
A More in-Depth Look Into Universe 25
- Phase A and B
Phase A, called the “strive period”, lasted 104 days. During this time, the mice adjusted to their new environment, marked their territory and started to nest. Then came Phase B, called the “exploit period”, where the population doubled every 55 days. On day 315, the population on Universe 25 rose to 620 mice. Though space was abundant, mice crowded in select areas and they feed on the same food sources. This made eating a communal activity.
However, since they were always huddling together, they stopped mating as much and the birthrate started to fall. This created an imbalance where one-third of the mice became socially dominant and the other two-thirds became less socially adept. Bonding skills started to decline, which marked the beginning of the end for Universe 25.
- Phase C
The high and low status of the mice became more pronounced and those at the bottom were rejected by females, so they stopped mating. They became outcasts because they didn’t have a role in society, so they wandered off and started sleeping and eating alone. Occasionally, they would fight among them.
By contrast, the males at the top became more aggressive and turned to aimless violence. Sometimes they would even roam around and violate other mice no matter their gender. These were the alpha males. The beta males, the mice between the alpha and the outcast, became timid and passive receptors of violence, which ended very badly.
Males completely abandoned their traditional roles in society, so the females had to defend their nests on their own. Consequently, many of them became aggressive and would turn violent towards their babies, while others would abandon their babies altogether and withdraw from mating. As you can imagine, infant mortality skyrocketed, reaching 90%.
Calhoun called Phase C the “stagnation phase” and attributed the overly aggressive and passive behavior to the breakdown of social roles and the increasing over-clustering. By day 560, the population ceased to increase and the mortality rate was almost at 100%.
- Phase D
Finally, we enter Phase D, the “death phase”. Among all this violence and lack of mating, a younger generation of mice became adults. However, they were never exposed to what we would call a normal society. As a result, they had no social skills and they never experienced normal or healthy relations.
They had no concept of marking territory, mating, or parenting, so all they did was eat, sleep and groom themselves. Calhoun called them the “beautiful ones” and they chose to be secluded, so they didn’t experience any violence or conflict but they also made no contributions to their society.
Calhoun noted that the death phase happened in two stages; the first death, which is the death of the spirit, meaning that mice had no purpose beyond existing and had no desire to mate, raise, or have a role in society, and the second death, which is the literal end of life.
In time, the number of mice that no longer wanted to mate or be a part of society grew more and more until they outnumbered the gangs. Universe 25 came to an end on day 920, where the population capped at 2,200. There was still an endless supply of food, water, and resources, but behavior sink had already taken hold and demise was inevitable. Soon enough, all the mice were dead.
What Does This Mean?
Calhoun, based on his observations of the beautiful ones in Universe 25, came to the conclusion that mice, just like humans, thrive when they have a sense of purpose and identity in the world they live in and find themselves. Experiencing stress, tension, anxiety, and the need for survival is what leads to engaging in society.
As the experiment showed, when all needs are accounted for and there are no conflict whatsoever, living is reduced to eating and sleeping, because that is all they have to do to survive. In other words, when necessity is taken away, life no longer has purpose and the spirit dies.
From the rise and fall of the mice utopia, Calhoun was able to draw these five basic points about mice and humans:
- Mice are simple creatures, but they need the skills for courtship, child-rearing, territorial defense, and a role to fulfill in the domestic and communal front. If they fail to develop those skills, they won’t reproduce nor find a productive role in society.
- Mice, like all other species, grow old and die. Nothing suggests that human society is not prone to the same developments that brought Universe 25 crashing down.
- If the number of unqualified individuals outgrows the number of openings in society, chaos and alienation are inevitable.
- Individuals raised in these conditions won’t be able to relate to the world and physiological fulfillment (eating and sleeping) will become their only drive.
- Just as mice thrive on complex behaviors, the concern for other people stemming from human skills and understanding is vital for our species to survive. If these attributes are lost, civilization as we know it would collapse.
Calhoun concluded that when complex behaviors related to vital functions (courtship, maternal care, etc.) don’t mature, social organization and reproduction just stop. So, the population will age and die, leading to extinction.
At the time, his conclusions resonated with the way people felt about overcrowding in urban areas and how it led to “moral decay”, but that leaves out many factors that contribute to that beyond overcrowding, such as prejudice and poverty.
Despite the grim picture Calhoun’s conclusions painted, he wasn’t implying that humankind would take a similar path. He described the parallels between his experiment and certain issues in society, but he also emphasized that humans are a more evolved species with the wisdom to avoid the trends he found.
After all, we have technology, science, and medicine, which give us many amazing skills, such as the ability to explore new environments, determine causation, avoid disasters, heal illnesses, injuries, and wounds, etc. Also, Universe 25 was not a natural environment, it was entirely manufactured and purposefully designed.
However, he did fear humanity could go down that dark path if the population grew beyond the job market’s capacity and cities became overcrowded. That’s why he dedicated his later career to exploring human advancement, which led him to the concept of space colonization, as well as city planning.
At the end of the day, humans are a more sophisticated species and the access we have to science, medicine, and technology can help us prevent such a fate. Not to mention, we have a wide variety of outlets that allow us to find meaning and purpose in life beyond eating and sleeping.
Featured photo is by Pixabay from Pexels