John Calhoun’s experiments with mice and rats in the 1950s through 1970s were groundbreaking in their attempt to study the effects of population density on behavior. His most famous experiment, Universe 25, started in 1968 and quickly spiraled into chaos. What began as a utopian habitat for mice ended in overcrowding, population collapse, and disturbing behavior patterns.
The population in Universe 25 peaked at over 2,200 individuals by the 560th day. The mice spent most of their time in the presence of hundreds of other mice, leading to stress and neglect of offspring. Some mice, known as “the beautiful ones,” secluded themselves in protected places, exhibiting chaste behavior and narcissistic introspection. Eventually, factors like low birth rates and high infant mortality led to the collapse of the society, with no baby mice surviving more than a few days by day 600.
Calhoun’s experiments were conducted with the intention of translating his findings to human behavior. During the late 1960s, there were widespread fears of overpopulation and dystopia, as popularized by Thomas Malthus and Paul Ehrlich. Ehrlich’s book, The Population Bomb, warned of mass starvation and societal decline due to overcrowding. Calhoun’s experiments were seen as evidence of what could happen in an overpopulated world, with behaviors like violence, lack of interest in sex, and poor pup-rearing labeled as “behavioral sinks.”
While Calhoun’s work initially tapped into fears of urban moral decay, interpretations have since evolved. It is now believed that the design of Universe 25 enabled aggressive mice to stake out prime territory, leading to overcrowding in the rest of the enclosure. Follow-up experiments with human subjects have shown that crowded conditions do not necessarily lead to negative outcomes like stress and aggression.
In conclusion, while Calhoun’s experiments with mice and rats in the 1970s may have painted a grim picture of overcrowding and societal collapse, it is important to remember that humans are not rodents. The lessons learned from these experiments have shaped our understanding of behavior in crowded environments and have highlighted the resilience of human beings in coping with challenging conditions.