By John Calhoun wanted to find out what the effects of overcrowding and population density would be. His experiment is one of the most striking to date. Read the results in the following article.
Although Universe 25 sounds like the title of a science-fiction novel, it actually gives its name to one of the most important experiments in social psychology. In 1968, ethologist and biologist John Calhoun built a utopian scenario with mice to find out what the effects of overpopulation would be. Five years later, that metropolis was devastated.
What happened during this period showed that the effects of progressive overcrowding can be very damaging at all levels . Although conclusions from animal models cannot always be extrapolated to humans, they do offer references that invite reflection. Let’s find out what that experience on a farm in Maryland consisted of.
“Universe 25” was originally a Garden of Eden for mice. Over the years, it became a living hell.
What was the “Universe 25” experiment?
John Calhoun was an ethologist who worked for much of his life for the National Institute of Mental Health in the United States . Overpopulation and overcrowding were a major concern for the scientific community in the mid-twentieth century; this renowned researcher addressed these issues prolifically from the 1950s onwards.
In 1968, he began the experiment known as “Universe 25” on a rural property in Poolesville, Maryland. The aim was to study behaviour in a context of species overpopulation. To this end, a veritable Garden of Eden was built for the mice, with multiple nesting areas and constant sources of water and food.
It was a kind of metal pen with tunnels, measuring 2.7 metres wide by 1.4 metres high. They had everything they needed, except space. Let’s find out how the progress and results were.
From the Garden of Eden to extinction
In 1968, four pairs of mice were introduced into the habitat; over time, the number of births doubled every 55 days . By month 19, from the start of the experiment, there were already 2,200 mice in the habitat. This reproductive rate was explained by the absence of predators and access to food.
It was an ideal society ; however, other phenomena of great interest to social psychology occurred. We will now point them out.
- Hierarchies were established, with dominant alpha males controlling the harems of females.
- Mice that lost fights with dominant males formed “dissident” groups.
- The fights and fights were constant, until the alpha males stopped defending their groups of females.
- Females had to initiate defensive behaviour for their offspring. However, the level of violence was so high that they ended up abandoning or neglecting their offspring.
- Between days 315 and 600, aberrant behavior emerged that broke the social structure.
- The females became aggressive and many stopped getting pregnant.
- Compulsive sexual behavior was born, including mounting of mice of the same sex.
- Cannibalism appeared.
- Social ties stopped being created.
- From day 600 onwards they stopped reproducing, defending territories and were limited to basic tasks for their health, such as feeding and grooming.
- The population, faced with the absolute breakdown of all social patterns, then began a progressive extinction.
In 1973, less than five years after the experiment began, the population dropped from 2,200 mice to none.
The babies born into this chaotic environment dominated by violence were not protected and no bond was established with them. This led to the complete extinction of this small society of mice.
What conclusions were drawn from the social experiment?
Dr. Calhoun did not hesitate to anthropomorphize the behavior of the mice, classifying them, throughout the experiment, as “juvenile delinquents” and “social dropouts.” Later, he was criticized for this type of terminology. That research was published in the journal The Royal Society of Medicine and the deductions he reached were the following.
1. The “behavioral sink”
Calhoun coined a new term. We call the set of aberrant behaviors that appear in crowded conditions and disrupt the social order a “behavioral sink .” When the number of individuals occupying a space exceeds equilibrium and harmony, three types of responses appear:
- Compulsive and irrational violence.
- The most basic ties, such as caring for one’s own offspring and children, are neglected.
- There is also the behaviour that John Calhoun defined as “the beautiful”. That is, there are individuals who withdraw and isolate themselves to focus only on tasks of personal hygiene and subsistence (food).
2. Some innovative behaviors
The famous experiment also provided some hope: some mice demonstrated innovative behaviour. Faced with a chaotic, threatening and deteriorating environment, a few individuals created tunnels in order to escape this hostile environment. Others built higher cubicles, so that they would not have contact with the most crowded and violent areas.
3. Individuals without status
One fact that was demonstrated was that when the mice stopped fighting for their territories, they lost status. The same happened to the females once they became aware that they could not take care of their offspring. The environment was so hostile that the social hierarchy broke down . Thus, social behaviors reflecting helplessness and abandonment emerged.
When social behaviors and the role of each individual do not mature, the development of a social organization or community does not appear.
4. A (questionable) analogy of the current world
John Calhoun presented his work on mouse behaviour as an analogy for today’s world. The context was also appropriate. This was the 1970s and population growth was high. Dr Edmund Ramsden of Queen Mary University of London published an interesting paper on this experiment in 2011.
- Calhoun’s studies were presented to reflect on or justify the need for population control, especially in the most disadvantaged communities.
- However, the experiment was interpreted with caution. It sparked an essentially academic debate as to whether this type of study could be extrapolated to human societies.
From “Universe 25” to the human world: what conclusions do we draw?
Today, unlike in the 1970s, birth rates have fallen significantly in developed countries ; so much so that we are an increasingly ageing society. Added to this is another phenomenon: it is common for young people to have no interest in sex. Have we reached Calhoun’s utopian scenario?
Be careful when extrapolating what happens in the laboratory to the real world
The social experiment on overcrowding reminds us that not all the phenomena we observe in the laboratory with animals can be transferred to the real world . In particular, this fact of research history is almost like a Rorschach blot: each person sees what he or she believes.
In addition, outside the laboratory there are so many variables influencing the interaction that they are impossible to study in a controlled environment, such as these rooms.
We should also bear in mind that the scenario designed for these mice was artificial and clearly intended to create population chaos, for example, by limiting the space. Perhaps in a natural environment the same thing would not have happened.
There is a bigger problem than overcrowding
The biggest problem with the experiment was not so much the limited space or the overcrowding, but the loss of individual functions. The abandonment of roles produced a social imbalance . However, if we transfer this to the human world, we identify a similar problem.
If we have a large number of people unable to fulfill their functions in society, alienation and social fracture can appear. If at some point we lose the ability to fulfill and execute complex behaviors, due to environmental factors, a problem would arise.
«Universe 25» versus current reality
Humans have the tools to avoid replicating what happened in Dr. Calhoun’s barn. We have technology, medicine, an ever-expanding science, and even the ability to explore new environments off-planet.
Our intelligence as a species serves a purpose. And it is none other than to facilitate innovation to survive in complex scenarios . It is what we always do successfully.