The Curious case of the ‘Rat Effect’ in Hanoi

At the height of Empire, France deployed administrators, engineers and technocrats to develop, modernise and control Southeast Asia. Following the alarming work by Alexandre Yersin in 1894, who discovered the role of rats and fleas as vectors in the propagation of bubonic plague which still held a profound cultural legacy in western Europe, the colonial state became increasingly concerned about the presence of rats in their cities. Nowhere more so than Vietnams Hanoi did rats become the focus of the colonial states attention.

At this point it is worth noting the contribution of the German Economist Horst Siebert with his ‘Cobra Effect’, in short the ‘cobra effect’ is when an attempted solution to a problem only exacerbates the issue and makes it worse. The French Colonials in Vietnam and their rats are a case book example, above and beyond that provided by British Colonials in Delhi.

Legacy fear of plague became enflamed when the symbols of progress and order lavished upon the wealthy European section in Hanoi, such as sewers and flushing toilets, became a wide-ranging underground transportation network for rats and the ideal breeding ground. The officials decided that rats popping out from a Europeans toilet would simply not do, this lead to what Historian Michael Vann calls ‘The Great Hanoi Rat Massacre’.

The colonial regime created a bounty programme that paid entrepreneurial locals for each rat killed, tails were used to count kills. As time passed Colonial officials began to notice rats with no tails in Hanoi…further investigation releveling a network of emergent rat farms, with tails removed and rats freed to continue to breed and pump life into the new lucrative sector of Hanois economy.

Case book cobra effect. Where French colonial officials had tried to solve the rat problem in Hanoi they underestimated the intelligence and imagination of the residents, the problem had simply increased (less a few tails).

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