Like many psychology and sociology papers, Mouse Utopia is now discredited because nobody could reproduce those results: https://www.gwern.net/Mouse-Utopia http

Like many psychology and sociology papers, Mouse Utopia is now discredited because nobody could reproduce those results: https://www.gwern.net/Mouse-Utopia https://www.gwern.net/Mouse-Utopia "Kessler 1966 only somewhat resembles Calhoun’s results: while Kessler does describe deviant mice behavior driven by density (such as homosexual matings) and high infant mortality/cannibalism, on the other hand, there are no population crashes or cessation of reproduction but stable populations after initial growth, there are no behavioral sinks, any ‘beautiful ones’ or ‘drinkers’ or ‘autistic’ mice are not described as such by Kessler, the mice are healthy overall, and transplanted mice revert"