Because there are omissions, simplifications, and inaccuracies in some general biology textbooks, obviously the modern theory of evolution must be wrong. This is the astounding line of reasoning that provides that backbone of Jonathan Wells' Icons of Evolution. It is the latest book in a series of neo-creationist productions, (this one dressed with the slightly more respectable label of "intelligent design theory" [Pigliucci 2000a]), to drive a wedge into the perceived perniciousness of modern science, and of biology in particular. This is another astonishing example of the fact that evolution-deniers seem to consider attacks on science popularizing as genuine intellectual feats, as if they had found huge wholes in the primary literature that truly constitutes the core of any respectable science.

Wells is a fellow of the Center for the Renewal of Science and Culture, which has been at the forefront of the neo-creationist assault on science over the last few years. Predictably, his book is endorsed by other fellows of the same institution and luminaries of the evolution-deniers movement such as Michael Behe (author of Darwin's Black Box), Phillip Johnson (Darwin on Trial and The Wedge of Truth, among others) and Dean Kenyon (Biochemical Predestination and Of Pandas and People). Wells himself seems particularly well positioned to engage in this never-ending debate given his double PhD in theology and molecular biology. Alas, Icons falls far short of a critique of evolutionary theory, or indeed of any significant contribution to the "evolution wars."

Wells' idea is simple: In the ten chapters that make up most of the book, he tackles an equal number of what he calls "icons," -that is, myths- of evolutionary biology, attempting to show that biology textbooks don't tell the whole story, are out of date, or oversimplify what is known. From there he concludes that because these icons are the best "proofs" of evolution, biologists don't have a leg to stand on and they should once and for all abandon their ideological positions and open their minds to a truer and better science, which of course must include the possibility of intelligent supernatural design (Dembski 1998).

There are several flaws with this line of reasoning, which I will examine in turn. First, textbook examples are no "proof" of anything. Second, Wells's critique of the ten icons is much less devastating than he seems to think. And third, science simply doesn't work the way Wells apparently conceives it.

The fact that science (not only biology) textbooks contain plenty of oversimplifications and inaccuracies, and occasionally even major conceptual errors, is not news to anybody and has always been decried by professional scientists and educators. There are sadly understandable reasons for this state of affairs. For one thing, general science textbooks are written by people who are either not practicing scientists or are directly competent in a fraction of the topics covered. Even when several authors collaborate, the situation does not improve significantly. Second, textbooks (unlike technical research books) are written largely to make money, both for publishers and for authors, and academic rigor sometimes gets sacrificed to accommodate more pressing matters, such as publishing deadlines. Third, pedagogical efficacy is often considered -rightly or not- more important than scientific rigor; after all, the audience is made of young students with little background in the discipline to be studied, not of professionals who understand the subtleties of the subject matter. Regrettable as these facts may be, to conclude from them that evolutionary biology is a big lie constructed on thin evidence is analogous to the preposterous suggestion of abandoning, say, quantum mechanics because many physics textbooks do not portray it accurately or may even make egregious conceptual mistakes in explaining it. It just doesn't follow, and it is pure wishful thinking on Wells's part to pretend otherwise.

As for the icons themselves, I will have to limit myself to a brief discussion of a couple of them. Let me therefore consider the first and last -and perhaps the most important- of the "icons": the Miller-Urey experiments on the origin of life, and the current status of the research on the origin of humans.

As is well known, in 1953 Stanley Miller-at the time a student of Urey-published a historical paper in which he demonstrated the possibility of the inorganic synthesis of some of the fundamental building blocks of life, given conditions that were thought to resemble those of the ancient earth. This experiment is still presented in many textbooks as the scientific answer to the question of the origin of life. And Wells is right in maintaining that it shouldn't be. For one thing, even if we do accept Miller's results at face value, they are far from constituting an answer to the origin of life question. At most they provide an interesting beginning. More importantly, the recent consensus among geochemists is that the ancient earth atmosphere was essentially chemically neutral, not reducing like the one Miller simulated.

However, textbooks should still devote space to Miller's experiment for its historical (and pedagogical) value: not only it was the first modern piece of empirical research on the origin of life, thereby taking the whole field away from metaphysical speculation, but it is also a great example of how science progresses by questioning its own assumptions and results.

As for this being an icon of evolution in Wells' sense, there are two problems with his position. First, Wells gives his readers the completely misleading impression that the field of research on the origin of life is still at the level of Miller's 1953 experiment, and that given the questionable validity of the latter, the whole enterprise is in disarray. Au contraire, this is an area of extremely fecund theoretical and empirical activity, with new hypotheses, findings and experiments being published at a very rapid pace (Lahav 1999; Fry 2000). More to the point of the creation-evolution debate, the Miller experiments and the whole question of the origin of life have nothing to do with the truth or lack thereof of evolutionary theory. By definition, evolution is something that happens after life originates on a planet, and cannot be invoked to answer the question of how this happened. By the same token, evolutionary theory cannot be blamed for not being able to solve the problem of the origin of life even if the latter might remain a mystery forever. It is certainly true, as creationists are fond of saying, that evolution requires life to have originated, but the two are entirely distinct scientific questions, addressed by different fields of research. For that matter, evolution also requires a universe to exist beforehand, but nobody would say that if we don't understand the origin of the universe this is a fatal blow to Darwinism (well, actually, naive young-earth creationists such as Duane Gish do, but that is another story: Pigliucci 2000b, chapter 11).

The "ultimate" icon in Wells' book concerns the story of human descent. This is perhaps one of the most peculiar chapters in the entire book, because even Wells is forced to concede ample ground to the evolutionists! He begins the chapter with the usual complaint about the naive scientists that were fooled by the "Piltdown man" hoax in 1912. I know of several scientists who feel the sting of shame, that Wells wants them never to forget, because of science having been duped by a fraudulent finding. But Piltdown was neither the first nor the last practical joke scientists will ever face. Furthermore, it is yet another beautiful example-which textbooks should promote-of how science really works. It is true that this alleged intermediate between humans and chimps was more or less accepted (not without challenge) for several decades. However, it is also true that the human fossil record at the time was so scant that it was very difficult to raise substantive objections to the Piltdown findings. More importantly, scientists-not creationists-uncovered the hoax, a development prompted by the very fact that more and more discoveries of genuine human and proto-human fossils made it quite clear that Piltdown didn't fit anywhere in the emerging picture. Since science works by a consilience of evidence (Wilson 1998), it was the progress of science in virtue of its self-correcting mechanisms that prompted evolutionists to reject Piltdown and eventually uncover the fraud. I have yet to find a similar example of acknowledgement of error in the evolution-denying literature, despite the fact that such errors have been ubiquitous in that literature.

Wells, as much as he desperately tries to debunk what to him is the most crucial component of evolutionary theory, the history of human descent, is backed against the wall by his own knowledge of biology. Unlike more naive creationists, he has to grudgingly admit that "Many human-like fossils have been found since 1912, and unlike Piltdown they appear to be genuine. Some have distinctively ape-like features, while others are more human-like" (p. 218) and "Obviously, the human species has a history" (p. 223). So much for destroying the ultimate icon.

But perhaps the most damning point about Wells' book is the general conception of science that it emerges from it. Given his scientific training, he should have known better. It is clear that either the education system at Berkeley has failed in his case, or that Wells does indeed have an ideological agenda (which he was forced to admit in a public debate with me at the University of Tennessee. See http://burns.tns.utk.edu/research/cb/evdebate.htm). Wells' whole argument hinges on the idea of the crucial proof of a scientific theory. If that pillar fails, the whole enterprise is useless. Now, Wells is far from showing that any of the icons are in fact fundamentally flawed or represent an insurmountable obstacle for evolutionists. But even if he succeeded, Wells' conception of science is so simplistic as being labeled by philosophers of science as "naive falsificationism."

Falsificationism, it may be recalled, is the idea proposed by philosopher Karl Popper (1968) that any amount of positive evidence is not enough to sustain a theory unless such theory also makes predictions that could-in principle-being demonstrated to be wrong, i.e., the theory is potentially falsifiable. Popper, however, did not advocate discarding a scientific theory at the first sign of trouble. Indeed, Thomas Kuhn clearly showed that real science is a lot more messy and that before switching paradigms the amount of trouble has to be substantial, or one risks living in a perennial state of flux in which no progress is actually possible (Kuhn 1970). The real "evidence" for evolution is not to be found in individual experiments, and it is certainly not to be expected in textbooks for beginning students. Rather, it is found in the enormous amount of facts about the biotic world that accumulate every year in the primary literature and that make no sense outside of the evolutionary paradigm. Components of this paradigm are constantly being tested in countless laboratories around the world, and-for the most part-the theory has withstood the test of time. More importantly, this is the way science really works, regardless of Wells' naive and ideologically motivated views that it should be otherwise (he admits in an online article, available at http://www.tparents.org/library/unification/talks/wells/DARWIN.htm, that he enrolled in his second PhD-in molecular biology-for the express purpose of "destroying Darwinism").

What have we to learn from this latest attempt at debunking evolution? Two things. First, that it is indeed a good idea to pay more attention to how our textbooks are written. This is not just so that individuals like Wells will not be able to use their cheap ammunition in a public debate, but more importantly because the "icons" can actually be properly used to show students that science is an engaging and ever changing enterprise, not a monolithic block of static knowledge. Second, we should finally get the message that evolution deniers are always at work, and that they are making inroads with both the public and politicians. How long until we get out of the ivory tower and start defending reason and science, as well as doing a better job at teaching them?

Acknowledgments. I wish to thank the following people for a critical reading of this manuscript and for providing me with valuable insights and suggestions: Wesley Elsberry, Jim Foley, Carl Johnson, Niall Shanks, Frank Steiger, and Dave Ussery.

References

Dembski, W. A. 1998. Reinstating design within science. Rhetoric & Public Affairs 1:503-518.

Fry, I. 2000. The Emergence of Life on Earth: a Historical and Scientific Overview, New Brunswick (NJ):  Rutgers University Press.

Kuhn, T. 1970. The Structure of Scientific Revolutions, Chicago: University of Chicago Press.

Lahav N. 1999. Biogenesis. Oxford (UK): Oxford University Press.

Pigliucci, M. 2000a. Review of  The Design Inference, by William Dembski. BioScience 50: 79-81.

Pigliucci, M. 2000b. Tales of the Rational: Skeptical Essays About Nature and Science. Atlanta: Freethought Press.

Popper, K. R. 1968. Conjectures and refutations; the growth of scientific knowledge. New York: Harper & Row

Wilson, E. O. 1998. Consilience: the unity of knowledge. New York: Knopf.