Darwin's proof, chapter 5

I am continuing to review Darwin's Proof, by C. G. Hunter. Here, I will review chapter 5, which, like chapter 4, tries to debunk the evidence for evolution. I cannot find a distinction between the material in chapters 4 and 5. It appears the material was separated into two chapters just to keep the chapter size smaller.

To understand Hunter's approach to evidence for evolution perhaps I can use a comparison. The same approach could be used to call into question any science. Let's look at Mendelian genetics. Geneticists claim that their theory predicts certain ratios in the offspring of crosses, such at a 3:1 ratio. However, there are many crosses in which we don't see that. Some crosses produce 2:1 ratios or 9:4 ratios. Sometimes the traits aren't even inherited from the father at all but only the mother. Geneticists will give various explanations for these anomalies, but they have so many excuses and explanations that any ratio at all is consistent with genetics.

That is what Hunter does. He gives a simplistic idea of what evolution should predict, then points out that there are many examples that do not fit this prediction. He admits that biologists have explanations for the exceptions, although he never bothers to tell his readers what they are so they can judge for themselves. He dismisses the explanations as ad hoc excuses and claims that because there are so many exceptions, any possible data will fit with evolution. Not once does he suggest that these explanations are actually tested. He implies that the explanations are accepted by biologists out of desparation, rather than being hotly debated.

I discussed the irony of this before--being able to fit any data describes intelligent design, for which all possible worlds really are consistent with it. Of course, any correct theory will explain what we actually see, but Hunter is wrong that all possible patterns can be explained by evolution, as I will discuss.

The first kind of evidence Hunter discusses in this chapter is the molecular clock. His first error is in thinking that the ticking of a constant clock is evidence for evolution, rather than a tool to determine relationships. The molecular clock was not even observed until a century after Darwin, and many evolutionary biologists have and continue to dispute it's reliability. Of course, Hunter quote mines these disputes to suggest the evidence for evolution is in question. The evidence for evolution is the nested pattern of similarities of DNA, not the fact that the changes occur at a constant rate. All biologists know that the clock isn't constant. He says that the fact that different parts of the genome tick at different rates is a problem for the theory, when it is not. This is one of those areas where we have well tested explanations for differences from his simplistic prediction. He says that a problem with the molecular clock as evidence for evolution is that we must first calibrate the clock with the fossil record. He again is unable to distinguish between molecular evidence for evolution and a clock as a tool to infer the time of speciation.

Hunter relies heavily on some papers criticizing molecular evolution by Christian Schwabe. It wasn't easy to find these papers, since they were published in the 1980s. Such outdated references should immediately cause suspicion. I eventually discovered that Schwabe is a chemist with some very radical views on evolution. He did publish some criticisms of molecular evolution 25 years ago, but all of his criticisms have since been addressed. Quite simply, Schwabe was wrong. Hunter never bothered to find more recent evidence or responses to Schwabe's criticism. Schwabe especially found problems with the evolution of the hormone relaxin, but a recent analysis has resolved the problems (Wilkison, TN, TP Speed, GW Tregear, and RA Bathgate. 2005. Evolution of the relaxin-like peptide family. BMC evol biol 12:5-14).

Hunter acknowledges that we have explanations for the descrepancies from perfect ticking of the clock (although he does not tell his readers what they are), but suggests that these are ad hoc rescues that could be used to explain any patterns, as I discussed above. These explanations are testable and are not accepted until they have been tested. We have evidence for lateral gene transfer, positive selection, etc. He implies that any pattern of molecular similarity would be consistent with evolution, but the truth is that we would have rejected common descent if genes of similar species weren't similar or if most genes did not fit in nested heirarchies.

Nezt, Hunter addresses the nested heirarchical pattern of evolution. This is good, because most creationists fail to even acknowledge this evidence. He says, correctly, that evolutionists say if we didn't find this pattern in nature, evolution would be falsified. He tries to avoid this by claiming that evolution in fact would explain any pattern, not just heirarchical ones. He says this would be true if evolution were very fast or non gradualistic. He pretends that disputes about gradualism within evolution include radical nongradualistic change that could produce non heirarchical patterns. I suppose if evolution were so fast that all evidence of ancestry were obscured, we would not see a heirarchy, or almost any other evidence for evolution. Such a radical theory would not be the theory we have. If organisms evolved that the current theory would be falsified, even if we replaced with a different theory of rapid evolution. Hunter thinks that if we replace one theory with another naturalistic theory, it is cheating. He would only be happy if evidence against evolution causes us to reject all possible naturalistic theories.

The fact is we have seen a heirarchical pattern with non living things that evolve by common descent, even with fairly rapid change. This includes the evolution of languages, chain letters, and Biblical manuscripts. The only way that Hunter can pretend evolution will predict a non heirarchical pattern is by basically inventing a new theory. Perhaps he can at least admit that even a moderately gradual theory of evolution will predict only a heirarchical pattern.

Hunter thinks that highly conserved proteins, which evolve very slowly, are a problem for evolution, because they could not have arisen in the first place (since they evolve slowly). It never occurs to him that proteins can evolve rapidly at first, but once they get a critical function they evolve much more slowly. In fact, we know of such proteins.

He also tries to attack the strong correlation between mophological phylogenies and molecular phylogenies--the fact that we get the same tree using both methods. He acknowledges this would be good evidence if it can be shown that there is no functional reason for them to be similar--if for example the hemoglobin of a frog can substitute for the hemoglobin of a mammal. He then makes an argument from ignorance, saying we do not know if this is the case or not. In fact, there is a vast amount of evidence showing that many molecular changes are neutral and proteins are interchangeable. This is even true of the coding part of proteins, but it is more obviously true in the various kinds of silent DNA--introns, psuedogenes, etc. There is no functional reason the difference between these should correlate with the difference between anatomical traits.

Nelson next mines the literature for a few instances when DNA trees don't correlate with morphological trees. Yes, we know that both kinds of trees have uncertainty and they won't have a perfect match. Very often when they don't match, we understand why--some of his exmaples involve lateral gene transfer or phylogenies that separated nearly a billion years ago and will have long branch attraction. He must at least admit that these problematic trees are exceptions for a rule of strong correlation. Again, he admits that there are explanations for the mismatches, and then implies that these are ad hoc excuses.

There is more in this chapter, but I have gone on long enough. I will finish in another post.