CALHOUN Experiment

The question of the future of humanity is not new. They approached the problem from both the purely scientific, religious or philosophical. What are the objectives of mankind? What instincts rule us? Do you strive for some higher purpose, is just about to spawn and fight for survival?

Many of the problems above questions provide us may “experiment Calhoun”, originally called “Mouse Utopia”. The exact question that this experiment is trying to answer is “what happens when individuals of a given species can provide everything you need to survive?”. John Calhoun created the mouse equivalent of human civilization development. The experiment was carried out on mice in 1968 and lasted four years. Despite repeated attempts the end result was always the same – unlimited access to food and lack of threats caused the extinction of the population.

But first things first …

Base assumptions (mouse heaven):

1. Unlimited access to food, water and materials needed to build a shelter.
2. Lack of life-threatening predators.
3. Maximum limited spread of infectious diseases (health care for the mouse).
4. The only limitation – a space that could accommodate up to 3840 mice.

The experiment:

Phase A – adjustment period (days 0-104)

  1. On the first day to the habitat were allowed in 4 males and 4 females.
  2. Initially, the mice had trouble adjusting to the environment and to each other.
  3. After a relative stabilization of the situation mice have created a sort of territorial division and started to build a nest.
  4. On day 104 began to be born the first “new” mouse.

Phase B – Rapid population growth – a period of exploitation of resources (105-314 days)

  1. Population doubling time is about 55 days
  2. Social organization established – frequency of litters proportional to social dominance
  3. The births tended to be concentrated in some sets of nest boxes (dominant males), while others (non-dominant males – withdrawn males = WM) had few or none.
  4. Although each living unit was identical in structure and opportunities, more food and water was consumed in certain areas. As the population increased, most mice associated eating and drinking with the presence of others. And crowding developed in certain units.
  5. At the end of this phase there were 3 times as many socially immature mice as there were socially established older ones.

Phase C – stagnation – a period of equilibrium (315-559 days)

  1. Population doubling time is about 145 days
  2. The male ability to defend territory declines
  3. The nursing females become aggressive, essentially taking over the role of the territorial males. This aggression generalized to their own young who were attacked, wounded, and forced to leave home several days before normal weaning.
  4. At this time, some unusual behavior became noticeable. Violence became prevalent. Excess males strived for acceptance, were rejected and withdrew. Social disorder became visible – a WM would attack a passive WM, who in turn would attack another WM. Certain individuals became targets of repeated attacks. These individuals would have badly chewed and scarred tails.
  5. Socially withdrawn male 29 makes a pan-sexual approach to male 16 who he recently saw attacked. Note how one assumes the female role. Males exhibit sexual behavior towards other males; you have rat homosexuality. They begin mounting the young.
  6. Incidence of conception decline and resorption of fetuses increases and dissolution of maternal behavior is observed. This lead to non-reproducing females.
  7. By midway in phase C, essentially all young were prematurely rejected by their mothers. They started independent life without having developed adequate affect bonds.
  8. Considering that there were 256 nest retreat sites in the 16 cells, one would not expect shelter to be a limiting factor until the population exceeded 3840. Due to the tendency of many animals to choose to crowd together in numbers in excess of 15 per nest site, at the peak population size of 2200 mice, 20% of all nest sites were usually unoccupied. Thus, there were always opportunities for females to select an unoccupied space for rearing young if they so chose.
  9. Social disorder – a WM would attack a passive WM, who in turn would attack another

Phase D – extinction period (days 560-1588)

  1. Population increase abruptly ceased on day 560 after colonization.
  2. Incidence of pregnancies decline very rapidly with no young surviving.
  3. The last conception took place about day 920
  4. Male counterparts to non-reproducing females were named the “beautiful ones”. They never engaged in sexual approaches toward females, and they never engaged in fighting. Their behavioral repertoire became largely confined to eating, drinking, sleeping and grooming.
  5. The capacity for reproduction terminated.
  6. The last thousand animals born never learned to develop the social behaviors, they never learned to be aggressive, which is necessary in defense of home sites; not engaging in any stressful activity, and only paying attention to themselves, they groomed themselves well so they looked like very fine specimens.
  7. Other young mice growing into adulthood exhibited an even different type of behavior. Dr Calhoun called these individuals “the beautiful ones”. Their time was devoted solely to grooming, eating and sleeping. They never involved themselves with others, engaged in sex, nor would they fight. All appeared as a beautiful exhibit of the species with keen, alert eyes and a healthy well-kept body. These mice, however, could not cope with unusual stimuli. Though they looked inquisitive they were, in fact, very stupid.



According to John Calhoun: “The conclusions drawn from this experiment were that when all available space is taken and all social roles filled, competition and the stresses experienced by the individuals will result in a total breakdown in complex social behaviors, ultimately resulting in the demise of the population. ”
No challenges, gradually worsens behavior subsequent generations of the population. This degeneration is inevitable and ends with the extinction of the population.

It calms me that but people are not mice, and in my opinion there always will be individuals who find different challenges drinking, eating and sleeping. Hopefully.

External links to related materials:

Behavioral Sink

How Mice Turned Their Private Paradise Into A Terrifying Dystopia

Escaping the Laboratory: The Rodent Experiments of John B. Calhoun & Their Cultural Influence

Calhoun’s experiment