Last week at the European Society for Evolutionary Biology (ESEB) meeting in Sweden, Michael Majerus of Cambridge University — one of world’s leading experts on the peppered moth, of textbook fame — gave a plenary lecture where he argued that his observations over the past 7 years, in his own garden in the UK, had corrected the shortcomings of Kettlewell’s classic experiments. Bottom line: peppered moths truly are “the proof of Darwinian evolution.”
Really. You can read his talk for yourself, here (click on the first link, “Stop Press,” for the pdf).
Majerus is unlikely to persuade skeptical evolutionary biologists that the peppered moth story, even when told with Kettlewell’s shortcomings corrected, is a good model for evolutionary theory generally. Twenty years ago, well prior to the hubbub about the peppered moth (started in large measure by Majerus himself), evolutionary geneticist Wallace Arthur doubted that industrial melanism — observed in many other taxa besides moths, by the way — provided much, or any, insight into the problem of macroevolution:
There is much current debate on whether the ‘micro-evolutionary’ studies of population geneticists, which deal with minor evolutionary changes occurring within present-day species, provides the whole story (or even an important part of the story) of ‘macroevolution’….equally one can argue that there is no direct evidence for a Darwinian origin of a body plan — black Biston betularia [melanic moths] certainly do not constitute one! Thus in the end we have to admit that we do not really know how body plans originate.
(W. Arthur, Theories of Life [Penguin, 1987], pp. 156, 180)
Arthur’s skepticism, like that of many other evolutionary biologists, has only grown in the intervening period.
So what does Majerus mean, when he says that the peppered moth is the “proof” of Darwinian evolution?
Only Majerus can say exactly, but here’s a worrisome clue: read what he saves for the Big Finish, Take-Home Lesson, of his ESEB plenary address:
I believe in the existence of god in that same way that Douglas Adams believed in the existence of god. Just as Terry Pratchett proved, through logical argument the existence of Father Christmas (well, actually it was the Hogfather), saying that if you can draw him, he must have existence, so Douglas Adams proved the existence of God. Moreover, he also proved that humans invented him or her.
Now place yourself in the role of an ordinary listener who, now and then, wonders about the enterprise of evolutionary theory, objectivity-wise. You know: dispassion, evidence, no stake in theology one way or another. All that.