Universe 25- John Calhoun's NIMH experiment

Leading up to 1972, John B Calhoun conducted a series of experiments under the guidance of the National Institute of Mental Health (NIMH). In these experiments Calhoun observed rats and mice populations coping with various living situations and environments.

These experiments culminated in Universe 25; a mouse utopia which lasted 600 days and ended in the extinction of all inhabitants.

http://www.cabinetmagazine.org/issues/42/wiles.php

https://en.wikipedia.org/wiki/Behavioral_sink

https://en.wikipedia.org/wiki/John_B._Calhoun