Behavioral sink - 'rat utopia' experiments that collapsed under overcrowding and social stress.

In his most famous experiment in the series, "Universe 25", population peaked at 2,200 mice even though the habitat was built to tolerate a total population of 4000. Having reached a level of high population density, the mice began exhibiting a variety of abnormal, often destructive, behaviors including refusal to engage in courtship, and females abandoning their young. By the 600th day, the population was on its way to extinction.

interesting read, especially the apparent parallels to human population growth, and the prime example of south korea.