Moths and Men
(This column was first published in the May 12, 2003 issue of The Buffalo News.)
Even scientific stories that seem too good to be true are sometimes false.
A body blow has recently been delivered to those evolutionists who have anchored their belief in natural selection on a study widely accepted for a half century and regularly included in biology texts. Creationists are, of course, delighted; more serious evolutionists turn to other evidence.
Many readers who studied biology in high school or college will recall the story. In the 1950s English lepidopterists (a.k.a. moth specialists) noticed a striking increase in the number of dark forms of the peppered moth, Biston betularia. This increase was particularly striking in the region around Birmingham. The coloring of the typical lighter moths appeared like lichen on tree bark, camouflage that gave them some protection from predators. But in industrialized areas everything, including tree trunks, was increasingly coated in soot. Aha, the theory went, surely the darker forms were evolving to improve their camouflage. The lighter forms, it seemed, were being found and eaten by birds because they were more apparent on the now darkened tree trunks.
A medical doctor and amateur lepidopterist, Bernard Kettlewell, was hired by the Oxford School of Ecological Genetics to test this idea. For several summers he carried out experiments near Birmingham and, for comparison, in rural Dorset. Based on his fieldwork, he claimed that twice as many dark moths as lights survived near Birmingham and three times as many lights as darks survived in Dorset.
His results were hailed with such encomiums as "Darwin's missing evidence." His story, illustrated with photographs he took of pale and dark moths taken against light and dark backgrounds, soon became accepted features of biology textbooks and science museums.
It now turns out that Kettlewell's evidence was questioned as early as 1969 with other journal exposes appearing in 1987 and 1999. Biologist Michael Majerus devoted a major part of his 1998 book on melanism to the study's problems. And now we have the popular entry, Of Moths and Men by Judith Hooper, providing the sad human background behind the story.
Some of the egregious study flaws that have been pointed out include: moths apparently glued to trees in large numbers, simply creating what critics have called a bird feeder; subjective choice of which moths were dark and which light; changes midway in the study protocol; ignored and possibly even fudged data; and worst of all faked photographs. The moths in the photos were not alive. As critic Nicholas Wade puts it, "Like the parrot in the Monty Python skit, they were ex-moths, winged members of the choir invisible, firmly glued or pinned to their perches."
For many evolutionists this came as a severe blow. When he learned of the faked photos, University of Chicago biologist Jerry Coyne wrote, "My own reaction resembles the dismay attending my discovery, at the age of 6, that it was my father and not Santa who brought the presents on Christmas eve."
Hooper's book makes clear the tremendous pressures placed on Kettlewell by his eccentric and tyrannical Oxford mentor, E. B. Ford. Kettlewell comes across as a well-meaning but browbeaten underling, too committed to his pet theory.
In many school texts Kettlewell's evidence remains as originally reported and when I questioned a high school biology teacher about the new evidence, he was not only unaware of it but scoffed at the possibility that the story was misleading.
A final point must be entered, however. Many biologists, including Kettlewell critic Michael Majerus, continue to support the original theory. Indeed, this study was terribly flawed, but their own more carefully designed experiments support the basic concept.-- Gerry Rising