John Calhoun

John B. Calhoun's famous rodent habitat studies documented that even while providing all requirements for a population, stress (which he induced through overcrowding) will always lead to extinction, with notable exhibition of bizarre and self-defeating behaviors along the way, and especially towards the end of the habitat's cycle. As modern living, and in particular the looming climate crisis, create ever greater stress in our own habitat, consideration of whether Calhoun's findings apply to our current situation may well be in order. A few articles are listed below. More at https://johnbcalhoun.com

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2009 - The urban animal: population density and social pathology in rodents and humans
John B Calhoun ... placed several rats in a laboratory in a converted barn where - protected from disease and predation and supplied with food, water and bedding - they bred rapidly. The one thing they were lacking was space... Unwanted social contact occurred with increasing frequency, leading to increased stress and aggression. Following the work of the physiologist, Hans Selye, it seemed that the adrenal system offered the standard binary solution: fight or flight. But in the sealed enclosure, flight was impossible. Violence quickly spiralled out of control... Their numbers fell into terminal decline and the population tailed off to extinction.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2636191

1973 - Death Squared: The Explosive Growth and Demise of a Mouse Population by John B Calhoun MD
Proceedings of the Royal Society of Medicine Volume 66 January 1973
John Calhoun's presentation on Universe 25 (one of his last) and what this might mean for humans. "For an animal so simple as a mouse, the most complex behaviours involve the interrelated set of courtship, maternal care, territorial defence and hierarchical intragroup and intergroup social organization. When behaviours related to these functions fail to mature, there is no development of social organization and no reproduction. As in the case of my study reported above, all members of the population will age and eventually die. The species will die out. For an animal so complex as man, there is no logical reason why a comparable sequence of events should not also lead to species extinction."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1644264/pdf/procrsmed00338-0007.pdf

 


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