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Mice Experiment Social Society

“Shocking experiment reveals the condition of our society!”

Such a headline is usually tied to articles describing Dr. John Calhoun’s behavior experiments.

Obviously, there’s a reason for that.

Among other things, the conclusions drawn up from Calhoun’s experiment are used to criticize abundant societies, to seek ways of organizing cities, and to explain the origins of feminist movements or the disappearance of masculinity.

In contrast to fake, poorly-photoshopped Albert Einstein’s quotes, Calhoun’s experiment has actually been carried out. One may have doubts about the conclusions of the experiment; however, we will discuss those a bit later.

First, let’s talk about the experiment itself. Although Calhoun’s discoveries are thought to be some of the most important in the history of psychology, (Hock, 2004 as cited in: Ramsden, Adams 2009) the scientist’s work is not as widely known as experiments performed by Zimbardo or Milgram.

Dr. Calhoun was an extremely famous ethologist who studied mainly behavior of mice and rats at the National Institutes of Health (USA). The most important experiments were conducted in the 1950s and 1960s. One of most shocking experiments performed by the behavioral researcher is known as the Mouse UtopiaExperiment.

During the experiment, a group of eight mice were living in ideal environmental conditions. The utopian universe provided rodents with unlimited access to everything necessary for the animals to survive. The mice were provided with food, water, and nesting material. Everything was available at their paw tips.

Although the beginning of the experiment seems ordinary, the course of the study, as well as the results, are quite astonishing.

What exactly did the experiment look like?


The four pairs of mice were living in an enclosed square area of 2.57m x 2.57m. They had the already mentioned unlimited access to food, water, and materials needed to build nests. The resources were calculated in such way that the mice could live without “worrying” about anything until reaching the number of 3840 rodents.

Other aspects of their lives were also taken care of.

The temperature was maintained at 20-30°C and it would change depending on the month. The inhabitants of the utopian universe enjoyed delicate and pleasant wind generated by a fan. Every four to eight weeks the whole area was cleaned out, removing the leftovers, excrement, and other municipal waste.

The sterility was also maintained, so the mice were free from any serious diseases. No predators had access to the mouse utopia; therefore, the animals didn’t have to fight for their lives.

Basically, the animals were living in paradise. They were safe, full, warm, and their houses were cleaned. Actually, they didn’t have to do a thing.

The Calhoun experiment lasted four years and it was divided into four phases. In order to retain symmetry I will provide you with details in four sections.

PHASE A  0-104 DAYS

Four pairs of mice were placed in the enclosed area.

Considerable social turmoil was noticed during the first 104 days. The mice were slowly trying to get used to each other as well as to adjust to the incredibly luxurious surroundings.

PHASE B  104-315 DAYS

During this period, social development was observed. The population doubled every 55 days on average until it reached 620 mice. The pace was quick. Whenever the litters reached sexual maturity they were becoming parents themselves.

There was some disproportion in the number of births in certain units, however. In some sectors as many as 111 litters were born; in others there were only 13 (eight times less).

Where does the difference come from?

The birth rate depended on the domination of males occupying particular units. The more active males were impregnating more females than their passive colleagues.

This graph shows the number of new births in certain units of the mice environment.

As the population grew, the best habitual units were being occupied by organized social groups. The Dionysian attitude of the participants in the experiment resulted in the increase of the number of young mice, which in turn surpassed the number of old mice three times by the end of the third phase.

That was the first sign suggesting that things may take an unexpected course. It is impossible to observe such a high birth rate in a natural mouse environment because the majority of litters simply die during their first days of life.

However, it was the phenomena observed in phase C of the experiment that were later discussed worldwide for decades.

PHASE C  315-560 DAYS

In phase C, slower population growth was noticed. The population now doubled every 145 days in contrast to just 55 days in the previous phase. This atypical behavior among the mice of the utopian universe was observed.

In a natural environment (even though the number of litters is lower than in the experiment) most young mice reach maturity. As a consequence, there are more mice than there are available positions within the hierarchy of a particular group. When this happens, those who can’t find a position in the mice society will emigrate.

However, there was no place to emigrate to during the experiment.

In the utopian experiment, many young mice were competing for a limited number of social positions. Those who failed to win the mouse race were dominated by other members of society in quite a dramatic manner.

The outcast mice would gather in the less attractive units of the utopian universe and withdraw from social interaction with other mice. Their position became so insignificant that their presence would not even provoke attacks from dominating males.


Nevertheless, their bodies were covered with wounds and scars.

These wounds weren’t the result of fights with other mice to attain a better social position though. They were from internal fights within the outcast group. From time to time one of the males would attack a chosen victim who had lost the ability to run away or fight back. After some time the victim would turn into the aggressor, accelerating spiral of violence by attacking other mice.

Not only were changes observed at the bottom of the social ladder, but also at the very top. The most territorial males were facing great challenges.

Even though certain mice failed in this mouse race, huge numbers of young rodents were still fighting for their own territory. Even the most combative males had difficulty fighting back against so many aggressors. The mouse universe was shrinking, and the intensity of defensive reactions was decreasing.

Due to the trouble in establishing the role of dominant male, peculiar changes in the behavior of female mice was observed.

The lack of guaranteed security made the nursing females more susceptible to potential attacks. Despite the fact that nursing females rarely involved themselves in aggressive situations in a natural environment, they were actually becoming the main aggressors in this experiment. They were often taking over the role of dominant males.

This aggression quickly spread to their own young. The nursing females often forced their young to leave home long before they become independent. The litters were attacked and severely wounded by the females also during labour.

By midway in phase C, almost all young were prematurely rejected by their mothers. These rejected mice started an independent life with no experience in social interaction or building relationships. Even when they did try to socially interact, life in a highly populated universe meant their efforts went unnoticed by other mice. The maternal, aggression, or love instincts were not developed at all. Great numbers of females didn’t get pregnant during their entire lifetime.

A new and unusual group of males called the beautiful ones formed.

These mice were never engaging themselves in fighting or sexual approaches towards females; thus, their fur was nicely groomed. Their behavioral repertoire was confined to eating, drinking, sleeping, and grooming. The beautiful ones were also avoiding any potentially risky types of behavior.

At the end of phase C, the typical, organized mice society no longer existed.

PHASE D  560-1588 DAYS

Population growth slowed drastically on day 560 after colonization. A small number of mice born before day 600 survived their childhood. The population was ageing very quickly. Three years after commencing the experiment, the average mouse lifespan was 776 days. That’s the equivalent of 80 human years.

The graph presents changes observed in the mice population during each phase.

Three months later only 122 mice were living in the society. The majority of the last half of the population constituted non-reproducing females and attractive, uninterested-in-sex males. Only two groups in reproductive age were left; however, they weren’t able to reproduce.

After time the population become extinct.

Dr. Halsey Marsden (1972, as cited in: Calhoun, 1973) carried out a similar experiment in which the mice from phase D were placed in a new and not overpopulated environment. Despite the better living conditions, these mice were not able to create an organized society. They lost the ability to reproduce and didn’t present a significant amount of sexual behaviors. The experiences of these mice within the “utopian society” resulted in the lack of ability to create a normal life outside of it.

What are the typical conclusions from this so-called “utopian” experiment?


Here is the quick list of the conclusions that can be found in numerous articles and comments to the article:

  1. The disappearance of masculinity in modern world (as seen in “the beautiful ones.”)
  2. Social exclusion makes victims extremely aggressive ( similar to the “rejected” mice living in the centre of the utopia.)
  3. The extinction of society resulting from prosperity (as seemed to happen by the end of the whole experiment.)
  4. Aggressive women taking over the role of men when there are no strong men around (as seen in the aggressive female mice.)
  5. The need to provide the new generation with decent workplaces or otherwise the whole generation will go to waste (similar to the disproportion of young and old people within the mice society.)

These are things that first come to mind after reading about this experiment. And these were the first thoughts that came to my mind too.

However, the “utopian experiment” does not actually support these ideas, and potential implications for our own society.

I will let Calhoun explain himself.


According to Calhoun, such phenomena may take place in societies where the older generations live longer than usual and the population growth is still within normal limits. The elderly do not die fast enough, and the younger generations wait impatiently to take over certain social roles. The competition between generations becomes much more severe.

After time, the old and the young start behaving in a way they would never do in the wild. Along with behavioral changes, the organization of society declines.

The rejection of young by their mothers and other adults creates an additional problem. The lack of opportunities to develop adequate affective bonds in childhood has a negative effect later on in life. Rather than intense, long-term relationships with a small family unit, shallow, short, and partial relations with a large number of others in the group, can lead to serious behavioral challenges.

The products of such living conditions are autistic-like individuals only capable of social behaviors necessary to survive. They are not able to do what typical mice do; i.e. engage in courtship, protect territory, take care of the young, create and be part of intragroup and intergroup hierarchy.

This lack of complex behaviors leads to the demise of the population.

Summing up, according to Calhoun, the reason for the above-mentioned result is too few or attractive social roles, and the decay of close and intensive relationships observed in early childhood. Overpopulation is the genesis of these two phenomena. Not the abundance of resources.


Only few people quoting this experiment understand its message.

Despite the popular name of the experiment, Calhoun failed to create utopian conditions. Quite the opposite, the main purpose of the experiment was to observe the reaction of mice when living in an overpopulated society. In order to create an actual utopian environment, the whole living area should have been enlarged before the start of phase C.

When thinking about human populations, the reason for extinction would not be prosperity but overpopulation. Those who think that prosperity spoils humans should visit the poorest countries in the world and see what people are able to do to provide their families with food and money.

However, here we are dealing with a much more significant question. Can we actually apply the results of the experiment to humans?

When discussing the experiment’s results with other researchers, Calhoun was referring to overpopulated Calcutta; the citizens of which seemed devoid of hope, capable of only simple behaviors. However, cities such as Hong Kong or Singapore are also overpopulated, but include examples of well-organized, prosperous, and active societies.

Jonathan Freedman, a scientist who was also interested in the subject matter of Calhoun’s experiment, was studying the negative impact of overpopulation on humans. It turns out there is no negative impact at all. Freedman suggested that it is not the overpopulation but the uncontrolled social interactions that are problematic. Subsequent experiments showed that the lack of privacy leads to a higher stress level and “overpopulation” feeling (Freedman, 1975).

It should also be noted that humans, despite the number of similar biological and behavioral mechanisms, are a bit more complex creatures than mice. Human culture, which separates us from other animals, has an equally significant impact on the way we behave as biology does. If the culture had not had that impact our social interactions would still resemble – very natural and based on biology – behavior of the cavemen.


Well, the shocking experiment outlined above does not describe the condition of our own society after all. Nevertheless, we should pay attention to the subsequent discoveries, and make sure we have our own private space to relax and recharge.

Also, when reading about different experiments, it is worth noting whether the author of the article provides a bibliography or other sources. I once read that bananas contain happiness hormones on a Polish equivalent of 9gag.com. Many websites often popularize content that is as emotional as it is simply unreliable, so it’s up to you to verify everything you read.


Calhoun, J. B. (1973). Death squared: the explosive growth and demise of a mouse population. Proceedings of the Royal Society of Medicine, 66(1 Pt 2), 80.

Freedman, J. L. (1975). Crowding and behavior. WH Freedman.

Ramsden, E., & Adams, J. (2009). Escaping the laboratory: the rodent experiments of John B. Calhoun & their cultural influence. Journal of Social History, 42(3), 761-792 ( via imprific.com ).

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