John B. Calhoun did not set out to make a giant hellhole for mice, but that's basically what he did in 1972. Universe 25 was Calhoun's twenty-fifth experimental rodent enclosure. In it, Calhoun included everything a mouse might need or want: food, water, a temperature-controlled environment, cozy mouse "apartments," and more. However, Calhoun knew Universe 25 wasn't going to stay a rodent paradise; all of his other mouse complexes went awry. But Universe 25 was the biggest failure yet.

Calhoun introduced eight white mice, four male and four female, to the environment. Just two years later, the increased mouse population essentially created its own apocalypse. The complex was crowded during its peak population. The mice got violent with each other, and mother mice even forgot about some of their babies. Calhoun called a particular group of mice "the beautiful ones," because they had separated themselves from the chaos, avoiding violence and death. However, these mice had no desire for social connections. They stopped mating and caring for their young. Watch the video below to learn how this disturbing experiment could relate to human life.