https://zh.wikipedia.org/zh-tw/%E8%A1%8C%E4%B8%BA%E6%B2%89%E6%B2%A6
https://en.wikipedia.org/wiki/Behavioral_sink
The Universe 25 experiment was a 1970s behavioral study by ethologist John B. Calhoun that created a "mouse utopia" to test the effects of overpopulation. Despite unlimited food and safety, the colony collapsed into extinction due to social breakdown and psychological withdrawal. [1, 2, 3]
The Setup
The Stages of Collapse
Once the population peaked at 2,200 mice on day 560, the society entered an irreversible decline. [1]
- The "Beautiful Ones": Many males became completely isolated and withdrawn, refusing to mate or fight. They did nothing but eat, sleep, and groom themselves, remaining physically pristine but psychologically detached. [1, 2]
- Hyper-Aggression: Other mice became fiercely territorial and violent, resulting in rampant cannibalism, random attacks, and failure to defend their young. [1, 2]
- Loss of Maternal Instincts: Females often abandoned their litters or attacked them, causing infant mortality rates to spike as high as 96%. [1, 2]
- Extinction: Eventually, normal courtship and mating stopped entirely. Even when physically capable of breeding, the mice had lost the social skills required to do so. The last conception occurred on day 920, ultimately leading to the total extinction of the colony. [1, 2, 3, 4]
Legacy and Criticism
However, many modern psychologists and historians criticize the study's conclusions. Critics argue that human beings are far more adaptable, complex, and capable of coping with density by creating social meaning and technology, making it inaccurate to directly compare human societies to isolated mouse colonies. [1, 2, 3, 4]
For a closer look at the enclosure, the behaviors of the 'beautiful ones,' and a breakdown of why this experiment became so infamous:
