November (Web-only) 2002

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Last week, we posted a letter from scientists Kevin Padian and Alan Gishlick in response to a piece by Jonathan Wells in the September/October issue of Books & Culture, dealing with the notorious peppered moth experiments. This week, we have given Wells an opportunity to respond. At stake are fundamental questions about truthfulness in debate—matters on which there should be consensus among all parties to the debate over Darwin's legacy.

In Of Moths and Men, Judith Hooper charges that defenders of the peppered myth have "marginalized" and "demonized" scientists who challenge them. Here Kevin Padian and Alan Gishlick obligingly prove her charge beyond a reasonable doubt.

According to the myth, light-colored peppered moths resting on pollution-darkened tree trunks are preferentially eaten by birds; the resulting natural selection explains why better-camouflaged dark moths became more common during the industrial revolution. The myth was largely exploded in the 1980s, however, when scientists discovered that peppered moths don't normally rest on tree trunks. Yet many biology textbooks still illustrate natural selection with staged photos of moths on tree trunks—usually made by pinning or gluing dead moths in place. The New York Times recently featured such photos as a now-classic example of "scientific fakery" (October 15, 2002).

Yet Padian and Gishlick continue to defend the discredited myth, claiming that a quarter of peppered moths rest on tree trunks and insisting that their claim is "based directly on the scientific literature."

A 1998 book by peppered moth expert Michael Majerus reported that between 1964 and 1996, scientists spotted 47 peppered moths resting in the wild, including 12 on tree trunks. Padian and Gishlick simply ...