In the 1960s, a scientist named John Calhoun created a “mouse utopia” where populations of mice would enjoy everything they needed, essentially without effort: Unlimited food, water, living space, population growth without predators and so on. It started with eight mice, who began to reproduce quickly, enjoying their newfound “utopia” with unlimited resources. Within 4 years, however, the population had become extinct through self-annihilation even though all the resources it needed for survival were readily available, including ample space to live.
What happened to Calhoun’s mice? He repeated the experiment multiple times using mice and rats. Each time the outcome was the same: Extinction within 1588 days. (Populations began to collapse at around 560 days, for reasons discussed below.)