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Friday, July 30, 2021

The legend of parachuting cats

Sustainable development, however defined, is about future cost and benefit, neither of which is known with certainty.

Written by Bibek Debroy |
Updated: March 31, 2016 4:50:18 am
(Illustration: C R  Sasikumar) DDT has been around since 1874. But Paul Hermann Müller discovered its insecticide properties in 1939, for which he received the physiology/ medicine Nobel in 1948. (Illustration: C R Sasikumar)

At a recent conference, despite its authenticity being of doubtful vintage, I again heard the story of parachuting cats. There are several versions of the apocryphal anecdote. Here is one. In the early 1950s, malaria broke out among the Dayak people in North Borneo. To counter malaria, the WHO had DDT sprayed throughout the region. (DDT was indeed sprayed in Sarawak in 1952-55, but it wasn’t DDT alone. Benzene hexachloride and Dieldrin were also sprayed.) Since mosquitoes hadn’t yet become immune to DDT, they died and malaria was controlled. But there was an unintended consequence. The houses were long, with thatched roofs. The caterpillar of a species of moth inhabited these thatches and ingested it. A wasp also laid its eggs in the thatches. The larvae preyed on the caterpillars. DDT killed the larvae and wasps, but the caterpillars survived because of immunity. Caterpillars proliferated and ate up the thatched roofs. Roofs caved in and had to be replaced with concrete roofs. (Wasps dying and caterpillars surviving is plausible, but there’s no evidence of this having happened. Nor is there any concrete evidence of concrete roofs ever having been constructed.) Lizards fed on dead larvae/ wasps and DDT passed into the food chain. Cats ate dead lizards and started to die.

Cat populations declined and rat populations increased, leading to plague and typhus. (There were some isolated reports of dying cats and increasing rat populations. But this had nothing to do with the food chain, or eating dead lizards. DDT and other insecticides had been sprayed inside buildings and left residues on the walls. Cats rubbed their bodies along the walls and licked their fur. That’s how cats died, probably from the more toxic and lethal Dieldrin, rather than DDT. Nor was there any actual outbreak of plague or typhus.) To get back to the story, 14,000 cats had to be parachuted in by the RAF. (The only evidence is from a village named Bario in Borneo, where an RAF transport plane did parachute in 20 cats.) Whatever be the truth, the legend has perpetuated and has become a perennial argument against DDT.

This column isn’t about DDT, which raises anti-DDT hackles among people who cite Rachel Carson’s 1962 Silent Spring, without necessarily having read it. Nor is it about the ban on DDT for agricultural use, as opposed to anti-malarial use, where again there are debates about the efficacy of DDT, as against other interventions like impregnated mosquito nets. DDT has been around since 1874. But Paul Hermann Müller discovered its insecticide properties in 1939, for which he received the physiology/ medicine Nobel in 1948.

Therefore, in 1948, and right up to the 1970s and even the 1980s, it was believed to be useful, ex-ante. The ex-post adverse effects of DDT, real or hypothesised, on birds, marine animals and perhaps even humans, were discovered later. For better or for worse, we take decisions in the present, without knowing what future science will reveal about adverse effects of present technology. Such information can establish today’s concerns to be false, or prove today’s decisions to be wrong. The future can have both positive and negative stories to tell. As an instance of the former, consider London’s horse manure crisis of 1894. At the time, London had 11,000 hansom cabs and with horse-drawn buses added to the tally, there were 50,000 horses. These produced copious quantities of dung and urine, not to speak of removal problems associated with horse corpses. (New York had 1,00,000 horses.) The problem of major cities being submerged in dung was widely debated and there was even an international conference on this in 1898. The invention of the automobile rendered this concern superfluous.

I am not dismissing environmental concerns. Far from it. But I am indeed drawing a distinction between ex-ante decisions, often designed to enhance human welfare, and ex-post discovery of consequences. On balance, as a species, are we better or worse off as a result of having discovered modern techniques of refining sugar? There’s a related point. Economists use the expression “Pareto superior/ inferior”. A situation is Pareto superior to another if it is better than the other in every respect. In actual public policy choices, rare is the situation of outright Pareto superiority/ inferiority. A situation is better in some respects, worse in others, and there is a tradeoff between costs and benefits. Had there been static tradeoffs between costs and benefits, life would have been simpler. But sustainable development, whatever its definition, is about future costs/ benefits, neither of which is known with certainty. It has been no different since the Brundtland Commission Report of 1987. To use clichéd imagery, who knows what will occur when a butterfly flaps its wings? Scientific and technological developments amount to far more than the flapping of butterfly wings.

Few people remember the origin of this butterfly wing metaphor. It is from a 1952 Ray Bradbury story, “A Sound of Thunder”. Significantly, this science fiction story was about time travel. Since we don’t have time travel and are unlikely to do so, the future is uncertain. Hence, there are legitimate concerns about the future and legends like parachuting cats proliferate. Is the future likely to be better than we take it to be? As a species, are we hardwired to be risk-averse and assume the worst? Is there a bit of Vitalstatistix (the sky bit) in all of us?

The writer is member, Niti Aayog. Views are personal.

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