Behavioral sink

Behavioral sink is a term invented by ethologistJohn B. Calhoun to describe a purported collapse in behavior that can result from overpopulation. The term and concept derive from a series of overpopulation experiments Calhoun conducted on brown rats between 1958 and 1962. In the experiments, Calhoun and his researchers created a series of "rat utopias" – enclosed spaces where rats were given unlimited access to food and water, enabling unfettered population growth. Calhoun coined the term behavioral sink in a February 1, 1962, Scientific American article titled "Population Density and Social Pathology". He later performed similar experiments on mice from 1968 to 1972.

Calhoun's work became used as an animal model of societal collapse, and his study has become a touchstone of urban sociology and psychology in general.