Universe 25- The fall of the Utopian dream

Today I want to write about sociology. While I find may aspects of the field rubbish, John Calhoun’s experiments from the 1960s are genuinely interesting and worth discussing. Let’s start from the beginning.

The Experiment

In the late 1950s, Calhoun began investigating the effects of overpopulation, initially using rats and mice. His most famous experiment, “Universe 25,” involved a large, enclosed space of 2.7 square meters with multiple levels. The enclosure featured tunnels, 256 pre-built nests (each capable of housing up to 15 mice), and constantly replenished food and water stations. The environment was meticulously maintained: the cage was cleaned and sterilized monthly, and the temperature was kept around 20°C.
Calhoun essentially created an ideal, utopian environment for the mice.

On day 0, he introduced four healthy, genetically normal mice (two male and two female) into the enclosure. After a 104-day acclimation period, the mice began to reproduce. Under these optimal conditions, the population doubled approximately every 55 days. This rapid population growth continued until around day 315, when the population reached approximately 620. Despite ample resources, the effects of high population density began to manifest, and behavioral anomalies emerged. Newborn mice faced a situation where established social roles were already occupied, creating intense competition. This constant struggle for territory and mates led dominant (“alpha”) males to abandon their roles, causing the social structure to break down. Males became aggressive, forming gangs that attacked females and newborns.
A significant number of mice exhibited pan-sexual behavior. Infant mortality soared to 96%, with instances of cannibalism despite the abundance of food and water. Three distinct groups formed:

• The rejected: These mice attempted to live in the center of the enclosure, frequently engaging in violence, cannibalism, and pan-sexuality.
• The females: Lacking male protection, the females clustered together in the highest level nests. The stress of this situation led them to kill their own offspring.
• The “beautiful ones”: This group, primarily consisting of males, avoided conflict and social interaction. They did not engage in reproduction or other social activities, focusing solely on eating and sleeping. They occasionally engaged in homosexual behavior.

Over the next 250 days, the population growth rate steadily declined. By day 560, the population peaked at around 2200. Around this time, no newborns survived. The population then began to decline rapidly, eventually becoming extinct within a few years.

Calhoun attempted to relocate four mice from the colony to a new, empty enclosure, hoping they would establish a new population. This failed. The relocated mice were psychologically damaged and unable to mate or reproduce.
They had experienced a “psychological death” before their physical demise.

The Results

The primary cause of the colony’s collapse was the intense competition for social roles. This struggle destroyed both the individuals involved and the social structure itself.

“Universe 25” was so named because it was the twenty-fifth experiment of this type. All previous experiments led to same results. Similar experiments with other animals, such as rats, produced same outcomes.

Calhoun extrapolated his findings to human society, suggesting that no matter how complex our society becomes, when the population exceeds the available social roles, similar behavioral patterns will emerge. However, despite Calhoun’s predictions, we might argue that humans are more adaptable than mice.
We haven’t yet experienced a complete “behavioral sink” (the scientific term for this phenomenon).
When we look at our current society, we don’t see all of these effects on a widespread scale.

Or do we?