DARWIN ON TRIAL: A Review Eugenie C. Scott, Ph.D., Executive Director, NCSE

Science and Religion

Law professor Phillip Johnson, a self-described conservative Christian creationist, believes that if evolution by natural selection is true, then the Universe, Earth, and humanity could not be the work of an omnipotent, personal God. Johnson believes that if evolution occurred, human life would have no meaning, and moral systems no foundation. In Darwin on Trial he attempts to demonstrate that evolution by natural selection didn't occur, thereby preserving his theological views. The book thus is primarily "about" religion and philosophy, using the science of evolution as a foil.

Like a lawyer, Johnson defines terms to favor his argument. Thus "creationist" becomes a tolerant, "anyone who believes God created", friendly term that covers about 90% of Americans including the 40% who believe that when God created, he brought forth the universe through evolution. Normally, these people are called "theistic evolutionists", but Johnson dismisses this moderate accommodation of science and religion as theologically unsound.

"Evolution" is negatively defined as an atheistic, naturalistic philosophy, equated with the philosophy of naturalism, and presented as a "chance" process. Letting a creationist define evolution is rather like letting a communist define capitalism! Scientists define evolution as the concept that the universe has had a history: what we see today -- stars, galaxies, the planet Earth, and earthly life forms -- is different from what existed in the past. Organic evolution, specifically, refers to living things having "descended with modification" from common ancestors who were unlike them.

The scientific definition of evolution makes no mention of theological issues such as whether God created. Science as practiced today is methodologically naturalistic: it explains the natural world using only natural causes. Science cannot explain (or test explanations about) the supernatural. There is also an independent sort of naturalism, philosophical naturalism, a belief (not science, but belief) that the universe consists only of matter and energy and that there are no supernatural beings, forces, or causes. Johnson's crucial error is not distinguishing between these two kinds of naturalism. That some individual scientists are philosophical naturalists does not make science atheistic any more than the existence of nonbelieving bookkeepers makes accounting atheistic.

Although science has made great progress by limiting itself to explaining only through natural causes, Johnson would have us allow the occasional supernatural intervention for those phenomena that cause problems for his particular theology. Though he has no objection to natural explanations for how fluids pass through a cell membrane, we need to leave room for a "whimsical creator" (p. 31) or God's "inscrutable purpose" (p. 71) to explain the origin of life, or the origin of complex body plans. Confusing unsolved with unsolveable, he wishes us to stop seeking natural causes for these phenomena. Johnson wishes to take us back to an earlier, less scientifically productive time when science had to wait for religious approval before daring to explain something that was religiously sensitive.

Evolution

Johnson is thus not a good source for learning about the nature of science. Can one use Darwin on Trial to learn about evolution? Not very well! Sometimes Darwin on Trial uses "Darwinism" to mean evolution by natural selection, sometimes to mean what scientists call the "synthetic theory of evolution" (the union of genetic theory with natural selection theory), sometimes to mean gradual evolution, and sometimes "Darwinism" means evolution itself. Sometimes "evolution" is used as a purely scientific idea, and other times it is confused with evolutionism, a naturalistic ideology that excludes the possibility of divine intervention. Just as science is not equivalent to philosophical naturalism, so evolution does not equal evolutionism.

Johnson attempts to convince the reader that evolution by natural selection did not take place, yet whether evolution occurred is one question, and what caused it is another. Modern scientists accept that evolution occurred, but differ over the relative importance of natural selection and other mechanisms, over whether the pattern of evolution is smooth and gradual or jerky and punctuated, over which characteristics link modern groups, and so on. He appears to use these controversies over how evolution occurred to press an unrelated point about whether it occurred. Moreover, he presents these disagreements as weaknesses, when in fact they are a normal part of science.

It would take a very long essay to criticize all or even most of Johnson's scientific errors. Many are recycled from earlier, long since refuted critiques of evolution presented by "scientific" creationists. As in creationist literature, we find the familiar "gaps in the fossil record", "natural selection is a tautology", "there are no transitional fossils", "mutations are harmful", "natural selection is not creative", "microevolution does not explain macroevolution", "natural selection only produces variation within the 'kind'", and "proof" of special creation by demonstrations of structural complexity such as the vertebrate eye and strands of DNA, as well as many other old saws. There are numerous books and articles refuting these misunderstandings, and if you contact NCSE, we will send you references.

Following earlier creation "science" literature, Johnson asserts that the Cambrian "explosion" of metazoa with hard body parts is a "great problem" for evolutionary biologists. We are supposedly stymied by the appearance of "nearly all the animal phyla" (p. 54). Does this mean that Cambrian strata contain living species? What does it mean that "phyla" appear? A phylum contains an enormous range of diversity. The phylum Chordata for example, contains animals as diverse as the worm-like Amphioxus and blue whales. Because chordates are found in the Cambrian, are blue whales? No! Animals of the Cambrian are generally primitive members of their phyla; the vast majority of modern species occur much later. Reading creationist literature (and Johnson's book) gives the misleading impression that all modern forms appeared at the same time.

Johnson implies that modern phyla are so different that they could not possibly have shared common ancestry, and argues that the lack of fossil evidence for connections between phyla is somehow fatal to evolution. Actually, links between the phyla do exist, suggesting common ancestry, and we do not require fossils to show these connections. To link prokaryotes with eukaryotes, we have biochemical evidence that mitochondria of nucleated cells are derived from certain non-nucleated bacteria (i.e., modern eukaryotes are descended from early eukaryotes that incorporated certain prokaryotes.)

Comparative anatomy has shown us similarities between the larval forms of echinoderms and the most primitive Chordates (i.e., that modern Chordata could be derived from invertebrate ancestors.) Molecular genetics suggests that some gene sequences for basic body growth and development have been inherited from very, very ancient ancestors: almost identical sequences of genes cause segmentation of the body in animals ranging from insects to primitive chordates like Amphioxus. Developmental biologists have discovered that the same gene sequence governs the development of normal eyes in both fruitflies and mice. Evolution is the only explanation that unifies a huge array of observations from comparative anatomy, biogeography, the fossil record, developmental biology, and molecular and biochemical biology.

Much evolutionary biology today is done in biochemistry laboratories. Johnson erroneously claims that molecular taxonomy "assumes" evolution. It doesn't, any more than does standard Linnaean taxonomy. The comparisons of molecules among species show certain species more similar to one another in their proteins or DNA than they are to other species. When these comparisons are grouped, something very, very similar to the taxonomy determined from comparative anatomy is discovered. Tigers and lions are more similar to one another than they are to pumas, but all of these cats are more similar to one another than they are to bears. Cats as a group are more similar to bears than they are to primates.

Johnson finds it "shocking", and "unexpected" that when lions, tigers and bears are compared biochemically with primates, they show approximately the same degree of genetic difference. On the contrary, this is exactly what would be expected if evolution were the process of branching and splitting of lineages that we think it is. The data reflect how long it has been since the gene pools were shared. Living lions, tigers, and bears are all recent members of a lineage (Carnivora) that split from a common ancestor with the other mammalian group called Primates, and later branched into a cat group and a bear group. Thus all modern species of lions, tigers, and bears have evolved the same length of time since they shared an ancestor with the primates, and show the same amount of genetic distance. Molecular information independently confirms a branching, hierarchical relationship among living forms that is best explained by descent with modification from shared ancestors.

Darwin on Trial teaches little that is accurate about either the nature of science, or the topic of evolution. It is recommended neither by scientists nor educators. Among the book's critics are evangelical Christian scientists who have criticized Darwin on Trial's scientific accuracy. For more reviews of Darwin on Trial, call or e-mail the National Center for Science Education

Also available from NCSE are short reviews of Darwin on Trial included in Reviews of Creationist Books, and an interview with Phillip Johnson.

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