Evolutionist Jerry Coyne habitually charges others with ignoring scientific evidence to advance a religious or other non-scientific viewpoint. With this in mind, it’s never out of place to remind readers of an episode from Coyne’s own past in which he was influenced in his scientific work by larger ideological battles.
The iconic image of the peppered moth (Biston betularia) is of course a staple in biology textbooks, meant to convince students that natural selection is real and can be observed on human time scales. But the reality is far more complex, as Jonathan Wells has shown in Icons of Evolution. The experiments done in the 1950s by Bernard Kettlewell, widely hailed as demonstrating industrial melanism to be an example of natural selection in action, were horribly flawed, flaws meticulously documented by Michael Majerus in his 1998 book Melanism: Evolution in Action.
Where Coyne Comes In
This is where Jerry Coyne comes in. In a review of Majerus’s book appearing in Nature in 1998, Coyne confessed to not knowing anything about the flaws in Kettlewell’s experiments until reading about them in Majerus’s book, even though these flaws had been well documented in the literature since the 1960s. Coyne registered his dismay at realizing he had been incorrectly teaching the example of the peppered moth as tantamount to learning that Santa Claus is the one who brings presents on Christmas Eve, not his father. This forced Coyne to conclude:
…for the time being we must discard Biston as a well-understood example of natural selection in action, although it is clearly a case of evolution.1
Coyne’s review quickly came to the attention of Darwin skeptics who were only too happy to trumpet the words of a noted evolutionary biologist now discarding one of the most iconic pieces of evidence for natural selection. I imagine Coyne caught real blow-back from his fellow evolutionists for giving aid and comfort to the enemy. I’m sure he wanted a chance to redeem himself.
He Did Not Have to Wait Long
Four years later (2002), science writer Judith Hooper published Of Moths and Men, a more popular criticism of the peppered moth story. Coyne jumped at the opportunity to review Hooper’s book, also in the pages of Nature. He was far more critical of Hooper than he had been of Majerus, concluding:
The dramatic rise and fall of the frequency of melanism in Biston betularia, occurring in parallel on two continents, is a compelling case of evolution by natural selection.2
So in just four short years, industrial melanism in the peppered moth had gone from something needing to be discarded as an example of natural selection in action to becoming once again a compelling case of natural selection in action, and without any new evidence coming to light. What drove this change?
We need not speculate, for Coyne tells us later in the review:
This issue matters, at least in the United States, because creationists have promoted the problems with Biston as a refutation of evolution itself. Even my own brief critique of the story (Nature 396, 35-36, 1998) has become grist for the creationist’s mill.3
It was Coyne’s fear of being seen as advancing a “creationist” cause that led him to reverse his position on the status of industrial melanism in the peppered moth. But this is not the end of the story.
Another Opportunity to Weigh In
In 2009, Coyne published Why Evolution Is True, a book for general readers designed to put the nail in the coffin of intelligent design approaches. In marshalling evidence for evolution to convince a skeptical public, Coyne had another opportunity to weigh in on industrial melanism in the peppered moth. After discussing the action of natural selection in laboratory experiments with bacteria, Coyne writes:
But perhaps it would be even more convincing to see the whole process in action in nature — without human intervention. That is, we want to see a natural population meet a natural challenge, we want to know what that challenge is, and we want to see the population evolve to meet it before our eyes.4
If Coyne believed his 2002 endorsement of industrial melanism as “a compelling case of evolution by natural selection,” this would be the perfect place to introduce it. What better example of natural selection happening before our very eyes? But Coyne does not employ the peppered moth here or anywhere else in his book. There is not a single mention of the peppered moth, industrial melanism, or Bernard Kettlewell anywhere in this book designed to argue for the truth of evolution! Given the opportunity to make the case for evolution in action, Coyne simply punts.
Instead, he follows up with:
We can’t expect this circumstance to be common. For one thing, natural selection in the wild is incredibly slow.5
It is pretty clear that Coyne’s feelings about industrial melanism are the one’s he announced in 1998 — the peppered moth should be discarded as an example of natural selection in action. (See my The Mystery of Evolutionary Mechanisms, pp. 117-128, for more on the ideological nature of the peppered moth story.) He reversed his position in 2002, it seems, because he feared losing credibility with his scientific colleagues. Instead of courageously standing for what he believed to be scientifically true, he backed down in the face of pressure to conform.
At least some others have the courage to stand for what they believe even in the face of potential criticism. Before Jerry Coyne criticizes them for being motivated more by ideology than science, he might want to first look in the mirror. Isn’t there something about people who live in glass houses not casting stones?
- Jerry Coyne, “Not Black or White,” Nature 396 (1998): 35.
- Jerry Coyne, “Evolution under Pressure,” Nature 418 (2002): 20.
- Coyne, “Evolution under Pressure,” 20.
- Jerry A. Coyne, Why Evolution Is True (Penguin 2009), 132.
- Coyne, Why Evolution is True, 132.