Does living in crowded places drive people crazy?

You may be thinking: yes—living under crowded conditions surely drives people crazy. And the reason why may be traced back to some unfortunate rats.

In the 1960s, the ethologist John Calhoun wanted to see how overcrowding would influence social behavior in rats. He placed rats in a confined space and allowed them to multiply with relatively little control (Calhoun, 1962). The results looked like scenes out of a horror movie: cannibalism, dead infants, and complete social withdrawal, to name a few.

Calhoun’s rats captured public imagination and inspired a surge of research on the psychological effects of density in our own species. Some studies found that people living in crowded environments indeed showed a variety of social pathologies, just like Calhoun’s rats. But other studies did not. Reviews of the early research concluded that popular fears about overcrowding may be unfounded (Lawrence, 1974).