The first was that of their spirit and their society. Calhoun later said that the creatures had died two deaths. The last mouse died on May 23 1973, four years and ten months after colonization. The mice had lost the capacity to rebuild their numbers-many that could still conceive, such as the “beautiful ones” and their secluded singleton female counterparts, had lost the social ability to do so. As the population had stopped regenerating itself, its path to extinction was clear. A few survived past weaning until day six hundred, after which there were few pregnancies and no surviving young. On day 560 the population peaked at 2,200 mice. Elsewhere, cannibalism, asexuality, and violence became endemic. Other males, a group Calhoun termed “the beautiful ones,” never sought sex and never fought - they just ate, slept, and groomed, wrapped in narcissistic introspection. Lone females retreated to isolated nesting boxes on penthouse levels. Normal discourse within the community broke down, and with it the ability of mice to form social bonds. Many found that so stressful, they gave up. Males faced a lot of competitors to defend their territory against. Young ones found themselves born into a world with far more mice than meaningful social roles. Past day 315, more than six hundred mice now lived in Universe 25, rubbing shoulders on their way up and down the stairwells to eat, drink, and sleep. Then they started to reproduce and the population increased exponentially, doubling every fifty-five days. It took months for the rodents to familiarize themselves with their new world. Or maybe not? Beginning of experimentįour pairs of disease-free mice, selected from the National Institutes of Health’s elite breeding colony, moved in on day one. There were no predators, the temperature stable. There was abundant food, water, and nesting material. universe 25Įvery 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.

What’s going on here? In 1972, John B Calhoun detailed the specifications of an utopia designed for mice: built in the laboratory. The full storyĬannibalism, asexuality, and violence. Colhoun had been creating utopian environments for rats and mice since the 1940s, with consistent results: overpopulation leads to explosive violence and hypersexual activity, followed by asexuality, self-destruction, and extinction. It was not the first time the ethologist had built a world for rodents. 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.

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