August 11, 2002


REVIEW : of 'Of Moths and Men: The Untold Story of Science and the Peppered Moth' by Judith Hooper (Karl Sabbagh, Washington Post)
The book is the story of an experiment that for many years provided the most powerful argument for the role of natural selection in evolution. In the 1950s, a British doctor, H.R.B. Kettlewell, investigated the genetics of a type of moth called Biston betularia. (Kettlewell is "Bernard" in the book. Rather oddly, Hooper, or should I say Judith, calls all her key figures by their Christian names throughout.) Kettlewell was interested in a phenomenon called "melanism," by which variants of the moth emerged in the 19th and early 20th centuries with darker wings than normal. This new variety coincided with increasing industrialization in Britain, and there were many biologists who believed that the phenomenon was a textbook example of evolution at work. They explained it as a result of the lighter moths being selectively eaten by birds because they were more visible on tree trunks that had become darkened with soot and smoke. Because more dark moths survived, their descendants, also darker, multiplied.

In fact, as Hooper shows with quotes from a wide range of standard biology primers, Kettlewell's work became legendary. "Through the textbooks," she writes, "the moths had become embedded in the collective consciousness. They were a teaching story, and you might as well try to eradicate E = mc2 or Newton's apple or Galileo at the Leaning Tower of Pisa."

But eradicate them she tries to do. [...]

As Hooper shows, it later turned out that in order to produce evidence that, in nature, melanism was due to birds eating the lighter moths, Kettlewell created a very unnatural experiment by glueing moths to the tree trunks and in far higher numbers than would occur naturally. Effectively, said one scientist, he was creating a bird-feeder that the birds learned to use.

Proving, once again, that all it takes for evolution to function the way our text books tell us it does is for a sentient being to intervene. Posted by Orrin Judd at August 11, 2002 6:03 AM
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