Assault on evolution

Wells' attack on the story of the peppered moths illustrates how his argument works. Beginning in the 19th century, it was widely noticed in England that the typical peppered moths -- white with dark speckles -- were becoming less common in areas where industrial air pollution had blackened trees, and darker forms of the moth were becoming more common. In the 1950s, Bernard Kettlewell performed experiments in which he released moths with different color patterns and observed the consequences of bird predation, which seemed to show that the darker varieties were less likely to be eaten in areas of industrial pollution, but more likely to be eaten in areas were the air was clear and the trees were covered with light-colored lichens. This became the clearest example of evolution in action, with natural selection favoring changes in the moths that would hide them from predation. Almost every biology textbook now has pictures of peppered moths on tree trunks to show how dark moths are harder to see against dark tree trunks.

The problem with such pictures, however, as Wells indicates, is that they are faked. Peppered moths do not normally rest on tree trunks. These moths fly at night and then hide under the upper branches of trees during the day. The textbook pictures come from scientists who have either placed live moths on tree trunks during the day when the moths become torpid or glued dead moths to tree trunks. Indeed, Kettlewell's experiments are now criticized by researchers as too artificial. Wells accuses biology textbooks of omitting this controversy and thereby concealing the flimsiness of the evidence for Darwinian evolution from students.

Wells does score a good point here in showing how biology textbooks oversimplify -- to the point of distortion -- the evidence for evolution. But to show that the evidence is more complex and more controversial than the textbooks usually indicate is not to show that there is no good evidence at all. The same researchers who criticized Kettlewell's study found that dark moths nevertheless do survive better in polluted, rather than unpolluted, woods, which suggests that they are somehow hidden from bird predators and thus favored by natural selection. One of those researchers concluded "that natural selection, the primary mechanism of evolution put forward by Charles Darwin, actually happens." Wells doesn't quote that.

Darwin never claimed that his theory could be demonstrated with a precision and certainty that would leave no room for reasonable doubt; he believed that no theory of the origin of species could be demonstrated absolutely. He anticipated almost all of the objections to his theory and devoted over one-third of "The Origin of Species" to considering such "difficulties." He admitted that some of the objections "are so serious that to this day I can hardly reflect on them without being in some degree staggered." And yet he insisted that his theory would emerge as highly "probable" to anyone who considered the "facts and arguments" in its favor.

Most of our knowledge in science rests on probability rather than certainty. If the alternative to Darwin's theory of evolution by natural selection is a theory of creation by a miracle-working designer, most of the empirical evidence is still on the side of Darwin. Certainly, no one knows how the existence of a supernatural designer could be rigorously verified by purely scientific means.

Wells is careful to refer to IDT only in passing because he wants to put all the burden of proof on the Darwinians, but he often implies that the only good alternative to Darwinism is "creation by design." And he warns his readers that Darwinism promotes a materialistic view of the world that denies the reality of a spiritual realm. His main conclusion is that "biology students are being taught materialistic philosophy in the guise of empirical science."

Next Page: Why evolution and religion aren't incompatible

• View blog reactions