The Mouse Utopia Experiment: A Study in Behavioral Sink

In 1958-1962, renowned behavioral researcher John B Calhoun conducted an experiment that would change our understanding of population dynamics and behavior forever. The Mouse Utopia Experiment, as it came to be known, was a groundbreaking study on the effects of overcrowding on rodents.

Calhoun's initial experiment involved placing rats in a complex environment with ample food, water, and shelter. The pens were designed to mimic a natural habitat, complete with elevated burrows, winding staircases, and nest boxes. However, despite having everything they needed to thrive, the rats began to exhibit strange behavior. They developed a 'behavioural sink,' where they voluntarily chose to live in overcrowded conditions, leading to significant changes in their behavior.

The rats' population grew rapidly, but eventually stabilized at 150 adults due to extremely high infant mortality rates. Calhoun and his team were surprised by these unexpected results and decided to conduct further research.

In his next experiment, Calhoun created a 'rodent utopia' – Universe 25 – a 3m x 4.3m room divided into four pens with an electrified fence. He calculated that the population of wild Norway rats could sustainably support a density of 5000, but the actual population never exceeded 200.

The Mouse Utopia Experiment spanned six decades, from Calhoun's early work in the 1940s to his death in 1995. His research aimed to explore the effects of population density on behavior and was inspired by earlier studies on population dynamics.

Calhoun's groundbreaking work has had a lasting impact on our understanding of behavioral psychology and the importance of considering population density when studying animal behavior. The Mouse Utopia Experiment remains one of the most significant and thought-provoking studies in the field, offering valuable insights into the complexities of animal social dynamics.

Mouse utopia experiment by john calhoun