This Podcast Will Kill You

Special Episode: Jon Adams and Edmund Ramsden & Rat City

February 24, 2026

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  • John B. Calhoun's rat experiments, conducted under the guise of a "rat utopia" with unlimited resources but limited space, revealed that social stress and unwanted interaction, rather than resource scarcity alone, led to severe behavioral breakdown and population collapse. 
  • The concepts of "personal space" and modern "stress" as physiological and psychological factors gained prominence in the mid-20th century, coinciding with Calhoun's research, which was subsequently used (and sometimes misused) to draw parallels with human urban overcrowding and social problems. 
  • Calhoun's legacy is complex: while he highlighted the importance of physical environment and space on well-being (influencing design and architecture), his work was often sensationalized to promote biological determinism regarding social issues, overshadowing his more nuanced suggestions for societal innovation through better spatial design. 

Segments

Introduction to Calhoun and Rat City
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(00:02:27)
  • Key Takeaway: The TPWKY Book Club episode features authors Jon Adams and Edmund Ramsden discussing their book, Rat City: Overcrowding and Urban Derangement in the Rodent Universes of John B. Calhoun.
  • Summary: The episode centers on John B. Calhoun’s influential but bizarre rat experiments concerning overcrowding. The discussion connects these studies to the book Rat City, which chronicles Calhoun’s rodent utopias. The host expresses excitement over the link between these experiments and the movie Mrs. Frisby and the Rats of NIMH.
Rats’ Cosmopolitan History
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(00:09:53)
  • Key Takeaway: Rats split from mice about 10 million years ago and have been commensal with human habitation since the late Pleistocene, spreading globally along human trade routes.
  • Summary: Rats have coexisted with humans since early communal dwellings in Eastern Asia. As human trade routes expanded, rats traveled along them, first the black rat and later the larger, more competitive brown rat (Norway rat). Their cosmopolitan lifestyle is due to their long history alongside human expansion.
Calhoun’s Research Origins
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(00:12:28)
  • Key Takeaway: Calhoun joined the Rodent Ecology Project in Baltimore during WWII, initially tasked with rat control, which led him to study rat behavior and ecology when chemical control proved insufficient.
  • Summary: The project shifted from chemical warfare against rats to an ecological approach after initial rodenticide efforts failed due to high rat reproduction rates. Ecologists observed that rat populations in Baltimore city blocks stabilized around 150 rats per block, never exceeding resources, prompting Calhoun to investigate why rats practiced birth control.
Towson Enclosure Setup
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(00:19:19)
  • Key Takeaway: Calhoun built a quarter-acre artificial enclosure in Towson, mimicking a city block, to observe rat behavior without human interference, meticulously documenting their social structures for 27 months.
  • Summary: The Towson enclosure allowed Calhoun to study a wild rat population with unlimited food and water but fixed space, enabling detailed observation using advanced tools like night binoculars. This study became the primary source for understanding the social behavior of brown rats in a controlled, yet naturalistic, setting.
Stress, Personal Space, and Calhoun’s Context
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(00:23:11)
  • Key Takeaway: The modern concepts of ‘stress’ and ‘personal space’ were coined in the mid-20th century, aligning with Calhoun’s focus on overcrowding effects, which he linked to physiological breakdown via stress hormones.
  • Summary: The concept of stress, encompassing both psychological and physiological effects, became popular around WWII. In Calhoun’s ‘rat utopia,’ stress from unwanted social interaction, not resource lack, caused physical organ damage (adrenal hypertrophy, heart disease) in lower-ranking rats, leading to population stabilization around 150 individuals.
Behavioral Breakdown in Density
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(00:35:34)
  • Key Takeaway: When density limits were artificially exceeded in the Casey’s Barn experiments, behavioral norms collapsed, leading to violence, neglect of young, and the emergence of ‘pathological togetherness’ and ‘behavioral sinks.’
  • Summary: In confined spaces, rats exhibited extreme behaviors like male gangs attacking females and pup cannibalism, behaviors absent in the Towson enclosure. Pathological togetherness involved rats becoming conditioned to feed only when clustered around a single hopper, leading to massive stress-related mortality rates up to 96%.
The ‘Beautiful Ones’ and Legacy
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(00:42:04)
  • Key Takeaway: Calhoun observed ‘beautiful ones’ or ‘dropouts’—rats so withdrawn they ceased social roles and reproduction, illustrating a breakdown of complex behaviors due to chronic stress.
  • Summary: Calhoun’s work influenced fields like prison and hospital design by emphasizing sympathetic architecture that allows for privacy and retreat, countering the idea that density inherently causes social collapse. However, his findings were often co-opted by politicians to justify increased policing rather than addressing underlying social and political issues.
Universe 25 and Final Decline
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(00:47:38)
  • Key Takeaway: Calhoun’s later mouse experiment, Universe 25, resulted in total population extinction after four and a half years, demonstrating that even when removed to a new environment, the withdrawn ‘beautiful ones’ could not resume reproduction.
  • Summary: Calhoun simultaneously ran shocking experiments predicting societal collapse alongside experiments attempting to culture ‘super rats’ toward altruism through environmental design. The focus on doom-and-gloom narratives and the rise of psychopharmacology in the 1970s led to funding cuts for his social science research, causing his influence to fade.