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The Universe 25 Experiment
A mouse’s perfect paradise… or not.
Between the late 1960s and early 1970s, American ethologist John B. Calhoun created a seemingly perfect utopia for mice. Calhoun’s predator-free, disease-free enclosure was furnished with limitless food and even an upper level with miniature mouse condos. Essentially, the mice would enjoy all the modern comforts people have come to expect today.
But the rodent society, dubbed the Universe 25, would quickly prove to be far from paradise.
The Experiment
To begin the experiment, Calhoun introduced four pairs of healthy mice into the enclosure. For the first 104 days, the mice explored their new habitat, marked their territory, and began nesting. Then, the population began to increase, doubling every 55 days.
Interestingly, even when the population was well under 1/4 of the enclosure’s capacity, most of the mice still crowded together in select areas. Eating, for example, was a shared activity so mice would group together during feeding times even though there was plenty of space to eat by themselves.
By the 315th day, the population reached 620 mice. Crowding behavior discouraged mating, heavily contributing to dropping birthrates. Universe 25 would now begin its slow but steady decline.
A prominent social ladder quickly took shape. Within the male population, the most dominant mice were characterized by their extremely aggressive behavior. The so-called “alpha mice” would often engage in wildly violent bloodbaths, proceeding to attack, rape, and even practice cannibalism at the expense of their peers. Disturbingly, these violent outbursts usually had no clear provocation or motive.
On the opposite side of the spectrum were the least socially adept mice who were completely excluded from mating. They spent their time moving between larger groups of mice, eating and sleeping by themselves. Occasionally, these mice would also fight one another.
Any mice that fell between these groups were rather timid and often became the victims of the violence perpetrated by their more hostile counterparts.
As the social roles broke down, the females took on more aggressive attitudes of their own. Taking…
