Book review: 'Rat City'

In 1946, on a quarter-acre wooded lot just off York Road in Towson, Johns Hopkins Professor John B. Calhoun constructed a rat enclosure that faithfully replicated a Baltimore City block, complete with "alleys" that cut through the underbrush and miniature fences that mimicked the cinderblock walls between yards. Working at the behest of a rat-plagued Baltimore looking to eradicate the pests, Calhoun released five pairs of Norway rats into the enclosure and retreated to his 20-foot-tall observation tower, settling in to witness the animals "establish their own empire" in the rat city he had built for them.

In Rat City: Overcrowding and Urban Derangement in the Rodent Universes of John B. Calhoun (Penguin Random House), British researchers Jon Adams and Edmund Ramsden document the decades Calhoun spent observing the rise and startling decline of the many rat empires he would set in motion.

Among his most consequential was the "rat universe" he created in 1958 in a Gaithersburg, Maryland, barn owned by the National Institute of Mental Health. While this universe was a pleasant one for the rodents, with plenty of food, water, and bedding, it lacked one fundamental element—space. Calhoun found that as the enclosure at NIMH became overcrowded, abnormal behaviors began to emerge among its populace: maternal neglect, extreme aggression, cannibalism. Eventually, the social disruptions led to a complete cessation of reproduction within the colony. Calhoun called the phenomenon "behavioral sink."

In an era of crowded cities, rising crime, and civil unrest, it didn't take long for Calhoun's ecological imperative to become a sociological one. Once motivated to save humanity from the rats, Calhoun now saw a mandate to save society from itself. Rat City tracks how Calhoun's ideas were adopted by city planners, architects, psychiatrists, politicians, and prison reformers to address various crises plaguing American society in the late 20th century.

For amateur science historians, Rat City provides a kaleidoscopic account of contemporary research into childhood phobias, canine intelligence, and the concept of personal space, just to name a few.