Between 1968 and 1970, American ethologist John B. Calhoun (1917-1995) conducted a behavioral study of captive mice within a nine-square-foot enclosure at a rural facility in Poolesville, Maryland. Within the enclosure known as Universe 25, several pairs of mice bred a population, which ultimately swelled to 2,200. Eventually, they established social orders that created inside and outside factions, and soon mating ceased altogether.
The study confirmed his grim hypothesis, based on earlier studies of the Norway rat in small settings. In his theory he suggested that overpopulation spawns a breakdown in social functions. That, in turn, inevitably leads to extinction.
Though wildly controversial when first made public, Calhoun’s theory has raised concern over the years that the social breakdown of Universe 25 could ultimately serve as a metaphor for the trajectory of the human race. Consequently, the “rodent utopia project” has been a subject of interest among architects, city planning councils and government agencies around the world.
Early Rodent Studies
Calhoun began his experimental research on rodents in 1947, when he studied an enclosed group of Norway rats at a barn in Rockville, Maryland. Supplying the critters with unlimited food and water, he expected to see their population swell to 5,000 over the course of the 28-month experiment. However, the population capped out at 200 after subdividing into smaller groups, each of which comprised merely a dozen individuals.
Continuing with these studies during the 1950s, Calhoun set up a more complex enclosure to examine how further groups of rodents would behave in a sterilized, predator-free environment. Over the course of these experiments, the same sequence of events would transpire each time:
- The mice would meet, mate and breed in large quantities.
- Eventually a leveling-off would occur.
- After that, the rodents would develop either hostile and cliquish or passive and anti-social behaviors.
- The population would trail off to extinction.
In 1962, Scientific American published Calhoun’s observations from his research in the article “Population Density and Social Pathology,” wherein he coined the phrase “behavior sink” to describe the results of overcrowding — namely the breakdown of social functions and the collapse of populations — in the enclosed rodent environment. Hitting the public just as vast urban expansion saw growing numbers of college grads flocking to big cities for work opportunities, many viewed the article as a warning of what could happen to the human race if populations continued to rise at their current rate.