and a 196872 experiment with mice called Universe 25. The mouse utopia experiment that turned into an apocalypse. How an experiment meant to create a rat utopia ended up as a cautionary tale about the end of days and death in more than one form. Calhoun's experiment remains a seminal work in the field of biology and continues to captivate and educate generations of scientists and laypeople alike. The rapid decline of the mouse population, despite having a perfect environment, highlights the importance of population control and the consequences of ignoring the limits of our resources. John Calhoun's mouse heaven experiment was not just a study of rodent behavior but also a warning to society about the dangers of overpopulation. The older mice gradually died off, and by the 27th month, the colony was extinct. By the 21st month, the birth rate had slowed, and soon, new births stopped altogether. These maladjusted behaviors spread like a contagion, affecting the birth rate and leading to a rapid decline in the mouse population. The aggressive behavior of the alpha males also caused stressed-out mothers to abandon their pups, leading to a decrease in infant survival.Ĭalhoun also observed deviant behavior emerging among the mice, including isolation, grooming obsession, and a lack of sexual interest. With the lack of mortality, dominant alpha males struggled to defend their harems from multiple challengers, leading to an increase in senseless violence. It was not the first time the ethologist had built a world for rodents. Juveniles in mouse heaven rarely died, unlike in the wild, and this resulted in a larger number of juveniles than normal. Every aspect of Universe 25, as this particular model was called, was designed to cater for the well-being of its rodent residents, increase their lifespan, and allow them to mate. In his 25th iteration, eight albino mice were introduced into the colony in July 1968, and their population doubled every 55 days, eventually peaking at 2,200 mice during the 19th month.ĭespite the robust population growth, Calhoun observed several serious problems in the colony. Calhoun calculated that his pen of wild Norway rats (or brown rats, aka Parisian rats, Hanover rats, street rats, common rats, sewer. He quickly discovered that mouse heaven could deteriorate into mouse hell in a matter of months. Universe 25 was his research pinnacle a rodent utopia.

However, this was not Calhoun's first attempt at a rodent utopia, as he had created 24 others before.

Calhoun also screened the mice to eliminate diseases, creating a utopia where mice could live without any worries and theoretically to an extremely old age. The mouse heaven was a 4.5-foot cube filled with everything a mouse could ever desire: ample food and water, a perfect climate, cozy nests made of paper, and 256 separate apartments accessible through mesh tubes. He built a colony called the Mortality-Inhibiting Environment for Mice, or more commonly known as 'mouse heaven.' Calhoun, who had a background in zoology, aimed to study and understand the factors that drive rodent population growth. John Calhoun, a biologist, captivated society with his fascinating experiments on mouse behavior.

Universe 25 mouse utopia