Addendum: On the day this item was posted, a school board member in Nebraska used slides of Well’s Icons of Evolution to argue that the school should teach “the evidence for and against neo-Darwinian evolution;” details here and here.
by Paul Braterman
The peppered moth provides a textbook example of industrial melanism and its reversal. Once a classroom classic, then much criticised, and finally rehabilitated through further observation, the story also shows how real science works. The response of the creationist and “Intelligent Design” community provides a textbook example of a conspiracy theory in action, with cherry-picked quotations, allegations of collusion and fraud, and refusal to acknowledge new evidence.
This moth comes in two main varieties, mottled pale (typica), and dark-coloured (carbonaria). The dark form was first noticed, as a rarety, in 1848. Then came widescale industrialisation and grime. By 1895, 98% of the peppered moths in Manchester were dark, and in 1896 it was first suggested that this was a camouflage effect; typica is well concealed against a pre-industrial treetrunk, with its mottling of lichen, but against a sooty background it is an obvious meal for any passing bird. J.B.S. Haldane, in 1924, applied his new methods of quantitative genetics to the speed of such changes, and inferred that carbonaria must have possessed something like 50% per generation advantage over its pallid competitor. An extreme case of Darwinian evolution.
(Let me define that term, since for their own reasons creationists habitually equate all modern biology with Darwin. Darwinian evolution requires just three components; inheritable variation within a population, competition between its members to survive and reproduce, and a difference in fitness between variants. Fitness, here, is simply the ability to survive and have offspring that are themselves fit. This then leads to the evolution of a population in which the variations that confer fitness have become more common. We now know, as Darwin did not, that the inheritable variation corresponds to differences in genes, and that mutations, arising from gene copying errors, give rise to an ongoing supply of new variations. That’s it.)
In the 1950s, Bernard Kettlewell, medical student turned naturalist, carried out a set of direct experiments to test the suggestion that industrial melanism was the result of selective predation. He released large numbers of moths, a mixture of typica and carbonaria, in both polluted and unpolluted woodlands. As expected if the predation-selection mechanism is operating, the survival rate was greater for typica in clean environments, while the opposite applied in environments that were polluted. Kettlewell then persuaded Niko Tinbergen to film the actual process in both kinds of environment. Tinbergen later shared the 1973 Nobel Prize for his work on supernormal stimuli (exaggerated forms preferred to the real ones), along with Konrad Lorentz (filial imprinting) and Karl von Frisch (bee signalling).
Subsequent decades saw the passage of clean air acts, the washing clean of trees by unpolluted rainwater and the return of lichens, and a recovery of the numbers of typica at the expense of carbonaria.
So here we had the clearest possible example of Darwinian evolution in action. Variation dependent on a single gene; a selection pressure, namely predation by birds; an evolved response, namely camouflage; and a change in the direction of evolution with circumstances as camouflage favoured first one variant, then the other. Or so it seemed.
There were, however, a number of detailed problems. Kettlewell had estimated the degree of camouflage by looking at moths pinned against tree trunks, and reports of his work used photographs of these to illustrate the point. However, peppered moths only rest on trunks about a quarter of the time, preferring the underside of branches. More seriously, his work had involved the daily release of unrealistically large numbers of moths, and this may have given an exaggerated impression of the degree of selection. Faced with an abundance of targets, birds might satiate themselves on the most visible, while at realistic abundances they would have been forced to look more closely. All these points and more were made forcefully in the book Melanism; Evolution in Action, by Michael Majerus, who nonetheless concluded that they did not undermine Kettlewell’s conclusion: “Differential bird predation of the typica and carbonaria forms, in habitats affected by industrial pollution to different degrees, is the primary influence on the evolution of melanism in the peppered moth.”
Majerus had a lifelong interest in lepidoptera, having caught his first butterfly at age 4, and built a moth trap when he was nine. At the time of his early death from mesothelioma, he was Professor of Ecology at Cambridge, and had just completed a lengthy experiment designed to overcome the shortcomings of Kettlewell’s studies. Lengthy, since only a few moths could be released on any one day, in order to keep their numbers within realistic limits. In accordance with his wishes, his posthumous website links to a Darwin Day 2004 lecture in which he defends Kettlewell’s work and outlines the projected research, and to his 2007 presentation at an international conference of the results of that research. A consortium of his colleagues later wrote up these results as a formal publication.
Majerus' Melanism was the subject of an extraordinary review in Nature by Jerry Coyne, professor at Chicago, which focused almost entirely on its criticisms of Kettlewell, reinforced by Coyne's own scrutiny of Kettlewell's original papers. Clearly shaken by their shortcomings, Coyne described the case of the peppered moth as “in bad shape” concluded that the peppered moth “shows the footprint of natural selection, but we have not yet seen the feet”, so that “for the time being we must discard it as a well-understood example of evolution in action”, and even compared his disillusion to his learning that Christmas presents came from his parents, not Santa. Notice how different Coyne's evaluation is from that in the book itself, where Majerus had reaffirmed Kettlewell's basic conclusions. Majerus had been studying moths since childhood. Coyne's main research focus has been on fruit flies, but this has also included studies of populations in the field. So as to why Coyne’s judgment of Kettlewell is so much sterner than Majerus’, we can only speculate. Coyne is now best known to the general public for his excellent book Why Evolution is True, and runs a highly enjoyable blog of the same name, noted for the forcefulness with which he expresses his opinions.
Majerus was not alone in commenting on the gap between Coyne's review and its subject. But the damage had been done. A review in Nature attracts a lot more attention than a feisty blog posting, and in this case it triggered a series of sensational headlines ranging from Staple of evolutionary teaching may not be a textbook case to The moth that failed (both in The New York Times) Darwinism in a flutter (Guardian), and Scientists pick holes in Darwin moth theory (Sunday Telegraph).
It gets worse. It is a small step from allegations of incompetence to suggestions of fraud, and that step is taken in Judith Hooper’s Of Moths and Men. Hooper is a journalist, who at one time worked for the science popularizing magazine Omni. In her acknowledgements, she says Majerus “spent hours teaching me engagingly about peppered moths”. For his part, Majerus in his Darwin day lecture describes her book as “littered with errors, misrepresentations, misinterpretations and falsehoods”.
Still, journalism is ephemeral. Its simplifications and exaggerations are soon forgotten, and Hooper’s book can now be bought online for pennies plus postage. Much more serious is the use made of the case by creationists, and most notably by Jonathan Wells in his 2000 book, Icons of Evolution; Science or Myth?, which has itself become an icon of creationism, the essay, Survival of the Fakest, that summarises it.
If Hooper gives us a single accusation of fraud, Wells offers us an entire conspiracy theory. He claims to have discovered the conspiracy by critically examining anomalies in his textbooks, late in his PhD. If so, he was merely finding what he was already looking for. He was, and I presume still is, a member of Sun Myung Moon’s Unification Church (the “Moonies”), and explains to his Church family that he did this PhD the better to undermine the established science: “Father's [Sun Myung Moon’s] words, my studies, and my prayers convinced me that I should devote my life to destroying Darwinism.”
Wells’s technique is to examine a selected group of textbook illustrations of evolution (the “icons”), criticise them on at times extremely tenuous evidence, and transform these criticisms into claims that the science being illustrated is itself known to be unsound. (As we shall see, the rejection of this line of reasoning is then used as further evidence of a cover-up.) Here I limit myself to the chapter on peppered moths, where the complaint is that the moths are portrayed hand mounted rather than naturally nested, and on the trunks of trees rather than on the boughs. “Nothing a little glue can’t fix”, says the essay sub-title, while according to the book, “The most serious [flaw] is that peppered moths in the wild don’t even rest on tree trunks. The textbook photographs, it turns out, have been staged.”
There was nothing new in any of this. Majerus had raised the same issues in his book, and dealt with them. Peppered moths do in fact rest on tree trunks, albeit only part of the time. But all of that is immaterial. Moths nesting naturally on branches show the same camouflage effects as staged images on the trunk (such as the one I have used here), and Majerus’ field photos prove it. Not only had he anticipated Wells’s “most serious” complaint, but he had shown that it made no difference to the science. And Wells includes Majerus’ book in his bibliography.
In public correspondence, Wells expresses himself as follows: “people like Majerus and Miller continue to deceive the public”, “Fraud is fraud”, “lying to biology students”, “scandalous”. In Wells’s opinion, “the peppered myth and its staged photographs should be abandoned, because they misrepresent the truth.” [Emphasis added] This although Majerus in his book had used only realistic and unstaged photographs, had devoted many pages to the moths’ natural choice of nesting place, had been highly critical in his discussion of Kettlewell’s work, and had spelt out what further research was still needed. All that Wells can see is an ongoing conspiracy to misinform, with Majerus, along with Miller and the rest of the textbook writers, among the conspirators. As for the idea of resolving the issues by observation, that does not ever seem to have occurred to him.
Wells is now a senior fellow at the Discovery Institute’s Center for Science and Culture, set up in 1996. According to its foundation document, this Center “seeks nothing less than the overthrow of materialism and its cultural legacies,” aiming “to replace materialistic explanations with the theistic understanding that nature and human beings are created by God.” Darwinian evolution is among the materialistic explanations opposed by the Center, which therefore promotes the pseudoscientific alternative of Intelligent Design (ID). In brief, ID claims that biological complexity is too great to have arisen from natural causes. It must therefore have arisen from the purposeful activity of an unspecified designer (or Designer). As for how the design is then embodied, we are told that we must look beyond natural causes. Supporters of ID repeatedly affirm that this argument is scientific and has nothing to do with religion.
Wells’s colleagues at the Discovery Institute are full of praise for Icons:
Jonathan Wells demonstrates with stunning clarity that the textbook examples Darwinists themselves choose as the pillars of their theory are false or misleading. What does this imply about their scientific standards? Why should anyone now believe any of their other examples?
This from Michael Behe, despite the fact that Behe himself accepts the broad historical fact of evolution. And then
Jonathan Wells … has brilliantly exposed the exaggerated claims and deceptions that have persisted in standard textbook discussions… in spite of contrary evidence.
This from Dean Kenyon, another Discovery Institute Fellow, who was converted to Young Earth creationism in the late 1970s.
This is one of the most important books ever written about the evolution controversy. It shows how devotion to the ideology of Darwinism has led to textbooks that are full of misinformation.
This from Phillip Johnson, a lawyer with no training in life sciences, inspiration of the Discovery Institute and co-founder and Program Advisor to the Center for Science and Culture, who believes in the separate creation of different kinds.
So there we have it. Because of the moth photos, and similar weighty matters, Darwinists (i.e. all mainstream life scientists) promote falsehood, mislead, have poor scientific standards, cannot be believed, exaggerate and deceive, ignore evidence, and fill their textbooks with misinformation. It is very important to realize this, because evolution is controversial, and Darwinism an ideology with devoted followers. It would follow that the numerous objections to Wells’s book in every science-based review (a few are listed here, here, and here, and in references therein), are based on ideology rather than any flaws in his reasoning. As Wells puts it in his response to critics, for evolutionary biologists “understanding nature is less important than finding ways to prop up Darwin's theory.”
More than a dozen years have passed since the publication of Icons, and a lot has happened in that time. Camouflage through choice of resting spot has been directly demonstrated, albeit with different moth species. The numbers of carbonaria have continued to decline as expected. Majerus completed his research programme, and a consortium of entomologists wrote up the results after his death. Kettlewell’s mechanism was confirmed in almost every detail, and is now generally accepted, even by former critics including Coyne. Using genetic mapping, melanism in British peppered moths has been traced to a single recent mutation; if a similar mutant arose in pre-industrial times, it has evidently left no descendants.
Icons of Evolution, however, has left descendants a-plenty. It has a special Tenth Anniversary website, which tells us “What people are saying about Jonathan Wells and Icons of Evolution.” (The people quoted all happen to belong to the Discovery Institute or its satellites.) In September 2012, the Discovery Institute’s Center for Science and Culture sent out a circular to parents, entitled “A Parent’s Guide to Intelligent Design”, which lists among its recommended resources a study guide to Icons, and a supporting video. The study guide publicity material also refers to Wells’s 2001 article, Survival of the Fakest. In May 2013, the Discovery Institute published a homeschooling textbook, Discovering Intelligent Design, which has 12 separate index entries for Wells, including one for his treatment of the peppered moth, and concludes from these that “The fact that these icons of evolution – inch beak sizes, moth color, or exaggerated embryo drawings – are so weak, and yet so commonly used, should tell us something. If evolutionary biologists had better evidence, you would know about it.”
Our thesis is confirmed by observation. Creationism is a conspiracy theory, and one with damaging consequences. Pity the homeschooled children it continues to recruit into the ranks of the misinformed.