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Only A Theory

Only A Theory August 25, 2008
I was thinking of calling this blog entry “Germ Warfare”, because there are striking parallels between the science of evolution and the science of germs. For most of us living in the United States and Western Europe today, it is hard to imagine a time when people did not believe the germ theory of illness, and the fact that people not only did not understand that illnesses were caused by microbes of various sorts, but that they actively resisted the idea because it ran so contrary to what people had understood up until that point.

I am no expert on the history of our understanding of germs. But what little I know leads me to believe that it was one thing to persuade the scientific and medical experts, and something else to promote and publicize the understanding among the general populace so that it could benefit the health and well being of a whole society.

Evolution is in much the same situation. Among experts, the evidence is clear and overwhelming, and it comes not simply from an idea of Charles Darwin’s published 150 years ago, but from the combined information from genetics, paleontology, biology and many other fields. New evidence is constantly pouring in, and it consistently supports an evolutionary understanding. Through genetics, we now can be as certain about the degree of relatedness between organisms as we can about anything in science. Evolution allows predictions to made not just about where fossils with certain features should be found, but also about where to look for precious commodities like oil. And without evolution, we would not be able to combat diseases as effectively. Evolution can be witnessed in the lab. Contrary to the claims that are sometimes made, there is probably no other theory that has been tested as rigorously and been confirmed so consistently.

One way antievolutionists give the impression that evolution is “a theory in crisis” is by quoting experts out of context. I thought of this as I was reading Kenneth Miller’s wonderful book, Only a Theory: Evolution and the Battle for America’s Soul (New York: Penguin/Viking, 2008). At one point the reader encounters the following sentence (p.15): “ID is gaining support because it’s correct and because it provides a new explanation of life that supersedes Darwinian explanations.” It probably won’t be long until this quote is mined by supporters of ID. But to take it out of the context of a hypothetical “what if” line of argumentation turns it into a statement that runs counter to the argument of the book. But that is what proponents of ID do. They take bits and pieces and spin them in such a way that those who are unfamiliar with evolutionary theory get a very different impression than those who know and understand it and the overwhelming evidence that supports it.

Although some have suggested the book is a revision of his earlier Finding Darwin’s God, this is certainly not the case. The book is more of a sequel, focusing far more attention on Intelligent Design, the most recent developments in biology and in science education, and seeks to get at the heart of why evolution, a fabulous scientific success story, is nonetheless viewed negatively by an astounding number of Americans. The answer is of course that evolution has been set for them in contrast to meaning, value and purpose. Faced with such a choice, humans will always choose the latter. But as Miller points out (and as I’ve said many times on this blog), if evolution is a threat to meaning and purpose, then so are genetics, and embryology, and all the domains of science in which natural explanations of aspects of our existence are provided. The solution is to realize that we can be material, biological entities and valuable. We do this in other areas, and once the popular imagination does the same with biology, the antipathy towards evolution will begin to dissipate (see pp.141-143).

Miller’s book presents many examples of the evidence for evolution. The blood clotting mechanism in vertebrates is often cited as an example of a biological capacity that is “irreducibly complex” and thus “intelligently designed.” Yet possible stages in its development have been identified. Moreover, if we could go back in time and look at the ancestor of the vertebrates that have the blood clotting mechanism, we’d expect to find it had the raw materials to make such a mechanism already scattered around its genome. If we examine the sea squirt, a chordate that is descended from a common ancestor with modern vertebrates, we find all but two of the relevant proteins in its genome (p.66).

One amusing example of how creationists themselves provide evidence for evolution is provided on pp.92-95. While young-earth creationists regularly assert that the intermediate fossils between modern humans and earlier primates are either clealy human or clearly ape, if you compare how various creationists assess specific fossils, they differ on all but one of six major hominid fossils (see the chart on p.95). In other words, these authors agree in claiming that these fossils are clearly human or clearly ape, and yet cannot agree on which are which, thus providing evidence that these fossils in fact do not fall in an obvious way into one classification or the other.

Other examples abound, and are powerfully persuasive. Our loss of the ability to produce our own vitamin C suggests we had an ancestor that lived in a place where citrus fruit was in abundance and was part of the diet, and thus the ability to produce vitamin C could be lost without natural selection eliminating the error. What we find as we dig deeper is that we share this inability not only as humans but with those primates most closely related to us, but not others. We also share the same exact pseudogene in the beta-globin gene cluster as other primates, and as Miller points out, agreeing on errors is a classic example of decisive evidence for plagiarism (pp.99-101).

Miller’s book offers a passionate and persuasive vision of science as not incompatible with faith, while also showing how intelligent design is a danger to science. I highly recommend Miller’s latest book, like his earlier ones, to anyone interested in understanding evolution, or why pseudoscientific religiously-inspired movement gain the appeal that they do, and what exactly is wrong with them. Both science and faith are the stronger for the coherent vision of both Miller offers.


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