Mouse Utopia Experiment

Behavioral sink” is a term invented by ethologist John B. Calhoun to describe a collapse in behavior which can result from overcrowding. The term and concept derive from a series of over-population experiments Calhoun conducted on Norway rats between 1958 and 1962. In the experiments, Calhoun and his researchers created a series of “rat utopias” – enclosed spaces in which rats were given unlimited access to food and water, enabling unfettered population growth. Calhoun coined the term “behavioral sink” in his February 1, 1962 report in an article titled “Population Density and Social Pathology” in Scientific American on the rat experiment. He would later perform similar experiments on mice, from 1968 to 1972.

Calhoun’s work became used as an animal model of societal collapse, and his study has become a touchstone of urban sociology and psychology in general.

In the 1962 study, Calhoun described the behavior as follows:

Many [female rats] were unable to carry pregnancy to full term or to survive delivery of their litters if they did. An even greater number, after successfully giving birth, fell short in their maternal functions. Among the males the behavior disturbances ranged from sexual deviation to cannibalism and from frenetic overactivity to a pathological withdrawal from which individuals would emerge to eat, drink and move about only when other members of the community were asleep. The social organization of the animals showed equal disruption. …

The common source of these disturbances became most dramatically apparent in the populations of our first series of three experiments, in which we observed the development of what we called a behavioral sink. The animals would crowd together in greatest number in one of the four interconnecting pens in which the colony was maintained. As many as 60 of the 80 rats in each experimental population would assemble in one pen during periods of feeding. Individual rats would rarely eat except in the company of other rats. As a result extreme population densities developed in the pen adopted for eating, leaving the others with sparse populations.

… In the experiments in which the behavioral sink developed, infant mortality ran as high as 96 percent among the most disoriented groups in the population.

Calhoun retired from NIMH (National Institute of Mental Health) in 1984, but continued to work on his research results until his death on September 7, 1995.

The experiments

Calhoun’s early experiments with rats were carried out on farmland at Rockville, Maryland, starting in 1947.

While Calhoun was working at NIMH (National Institute of Mental Health) in 1954, he began numerous experiments with rats and mice. During his first tests, he placed around 32 to 56 rodents in a 10 x 14-foot case in a barn in Montgomery County. He separated the space into four rooms. Every room was specifically created to support a dozen matured brown Norwegian rats. Rats could maneuver between the rooms by using the ramps. Since Calhoun provided unlimited resources, such as water, food, and also protection from predators as well as from disease and weather, the rats were said to be in “rat utopia” or “mouse paradise”, another psychologist explained.

Following his earlier experiments with rats, Calhoun would later create his “Mortality-Inhibiting Environment for Mice” in 1972: a 101-inch square cage for mice with food and water replenished to support any increase in population, which took his experimental approach to its limits. In his most famous experiment in the series, “Universe 25”, population peaked at 2,200 mice and thereafter exhibited a variety of abnormal, often destructive behaviors. By the 600th day, the population was on its way to extinction.

Cultural influence

The 1962 Scientific American article came at a time at which overpopulation had become a subject of great public interest, and had a considerable cultural influence. The study was directly referenced in some works of fiction, and may have been an influence on many more.

Calhoun had phrased much of his work in anthropomorphic terms, in a way that made his ideas highly accessible to a lay audience. Tom Wolfe wrote about the concept in his article “Oh Rotten Gotham! Sliding Down into the Behavioral Sink”, later to be made into the last chapter of The Pump House GangLewis Mumford also referenced Calhoun’s work in his The City in History, stating:

No small part of this ugly barbarization has been due to sheer physical congestion: a diagnosis now partly confirmed with scientific experiments with rats – for when they are placed in equally congested quarters, they exhibit the same symptoms of stress, alienation, hostility, sexual perversion, parental incompetence, and rabid violence that we now find in the Megalopolis.

Calhoun’s work has been referenced in comic books, including Batman and 2000 AD.

Calhoun himself saw the fate of the population of mice as a metaphor for the potential fate of man. He characterized the social breakdown as a “spiritual death”, with reference to bodily death as the “second death” mentioned in the Biblical book of Revelation 2:11.

Calhoun’s work with rats inspired the 1971 children’s book, Mrs. Frisby and the Rats of NIMH, by Robert C. O’Brien, which was adapted into a 1982 animated film, The Secret of NIMH.

Applicability to humans

See also: Model organism

Controversy exists over the implications of the experiment. Psychologist Jonathan Freedman’s experiment recruited high school and university students to carry out a series of experiments that measured the effects of density on behavior. He measured their stress, discomfort, aggression, competitiveness, and general unpleasantness. He declared to have found no appreciable negative effects in 1975. Researchers argued 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.”

Behavioral sink – Wikipedia

An important point to notice in the mouse utopia experiment is that the limiting factor of this experiment was space. This basically shows that space is one of the most decisive factors in the development of the social behavior of animals including humans. From the experiment, it was observed that as time passed with the lack of space, the mice started to pass on the negative behaviors to the coming generation and this became a chain. This means that population condensation surely comes with a number of adverse consequences. Another article ‘The Power of Choice’ by Quintus Curtius explains a similar study to mouse utopia experiment but it was performed on the people of Easter Island. It tells that when humans first arrived there in almost 900 A.D, the area was covered with trees and could have sustained a high population. Similar to the conditions of mouse utopia experiment, there were no external factors of stress such as predators however, the resources were endless. But with time, the island became overly populated. Quintus explains what befell the Islanders:

“The islanders then began to compete with each other more and more fiercely for an ever-declining volume of natural resources; vendettas multiplied, intertribal warfare flared, and a pall of hostility and fear descended on the island. As the trees vanished, the Islanders were unable to build boats to escape to other islands: they became trapped in their own hell, doomed to fight each other in perpetuity for the last crumbs that the barren land could offer. Eventually, the islanders began to starve, and feed—literally—off each other. As wild meats became unavailable, and escape off the island became impossible, the natural consequences followed. Cannibalism stalked the island, animating its folklore and infecting its archaeological sites. Perhaps the islanders compensated for their misery by focusing more and more on the empty ritual of building and raising statutes, as their means of sustenance melted away.”     

One may argue that this behavior would not prevail among humans and thus this couldn’t happen to humans because humans have large bands of land that are still unpopulated, it has to be noted that in the experiment even at the peak population, only half the colony space was being used. The mice had a tendency to overpopulate certain sectors of space, but they did not. Hence, it is not just about space but a limitation on social interactions as well that leads to such behavior. There are natural limitations on the level of social interaction humans can manage on a daily basis, just like with the mice.

Mouse Utopia Experiment | Mr. Pest Guy

This film is a trimmed version of a longer set of stitched-together reels that contain remarks by and interviews with National Institute of Mental Health scientist John B. Calhoun, as well as extensive footage of the thousands of mice Calhoun studied over many years. In Mouse City, Calhoun provided his research subjects food, water, bedding, protection from predators–all that they needed except adequate space. The results were destructive and dramatic. Based on these experiments, Calhoun drew conclusions about human behavior in overcrowded conditions, such as high-density public housing.

The National Library of Medicine

The Mouse Utopia Experiments | Down the Rabbit Hole

As the world recovers from World War II and fears of overpopulation swell in America, one researcher begins constructing horrifying experiments to model it.


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One comment

  1. vᚻællKᚱᛁᛗvosᛏ · January 21, 2021

    Reblogged this on Vermont Folk Troth.

    Liked by 1 person

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