Evolution -- Book Review by Lloyd Geering

Evolution: A Theory in Crisis by Michael Denton, Adler & Adler, reviewed by Lloyd Geering

The reading of this book reminded me of an incident from my student days in the thirties at the University of Otago. The Science Students' Debating Society challenged the Evangelical Union to a debate on evolution. They planned it as a bit of fun to show up the ignorance of conservative Christians. They were quite taken aback when they lost the debate on the decision of a neutral judge. They had not even read Darwin's Origin of Species. To their surprise their opponents had not only read it but knew enough to point out the many weak links in Darwin's reasoning and the many suppositions he had had to make.

This book, by an Australian medical doctor and scientist, does something similar but with considerably more scientific skill and in the light of the knowledge of molecular biology which has been gained since that time. It is a salutary reminder that no scientific conclusion should ever be allowed to drift into being an unexamined dogma. To be truly scientific one must always be reviewing the evidence in the light of fuller evidence and experience. Science, even at its best, never reaches finality simply because it is a human enterprise and its conclusions are always subject to continual review.

Some of the new evidence in this book, particularly in the area of molecular biology, is of a technical nature whose validity I am not in a position to judge. But there is quite sufficient in plain language to cause the average lay person to pause and think again about the Darwinian theory of origins.

There are places where Denton goes too far. It is not true to say that for Darwin "chance ruled supreme", or that Darwin saw evolution as "an entirely random process". On the contrary, living as he did in the aftermath of Newton's view of the world as a mechanical universe operating according to its own internal laws, Darwin believed he had discovered one of those laws -- "the law of evolution of species by natural selection" In other words "natural selection", far from being a random process, was for Darwin a mechanism built into the natural processes. It involved chance but what occurred was, he believed, not wholly the result of chance. What Darwin believed was that evolution was the result of both "chance and necessity", to use the words of Democritus, revived by molecular biologist Jacques Monod in his book of that name.

It is unfair to describe Darwin, before joining the Beagle, as a "Bible-quoting fundamentalist". Indeed it is anachronistic to say "nineteenth- century England was steeped in biblical fundamentalism". Fundamentalism is a 20th century phenomenon and refers to the blind commitment to the literal understanding of the bible in spite of overwhelming evidence to the contrary. In the early 19th century there was little cause to doubt the Bible at face value and Darwin simply shared beliefs which were universally accepted. The fact that his views changed as he accumulated his evidence shows he was far from being "a fundamentalist"; and the fact that his views were so quickly accepted, along with much other new evidence then challenging the traditional understanding of the Bible, showed that many people were reasonably open-minded.

Denton rightly points out that Darwin presented "two related but quite distinct theories". The first (the "special theory") is more restricted in scope, simply proposing that new species can arise by natural selection. The second theory of Darwin (the "general theory") claims that the "special theory" can be extended universally to explain the tremendous variety of all forms of earthly life.

Denton is not himself a "creationist", anxious to defend the biblical story of origins. He is a scientist wishing to warn that the Darwinian theory of the origins of species is far from providing an adequate explanation. He concedes, in his first five chapters, that "Darwin's special theory was largely correct...there can be no question that new species do originate in nature...The validation of Darwin's special theory..has been one of the major achievements of twentieth-century biology".

The very success of the special theory, however, has had the effect of enhancing the general theory of evolution to which Darwin proceeded on the basis of it. But arguments from the known nature of small-scale evolutionary change do not necessarily prove long-term evolutionary processes. As Denton pertinently points out, there is "obviously an enormous difference between the evolution of a colour change in a moth's wing [something which has been observed] and the evolution of an organ like the human brain".

By resort to much technical data Denton sets out to show that the differences between some genera is so great that they defy any explanation by gradual processes. This raises the question of whether there has been sufficient earthly time available for the evolution of all known species to have taken place by gradualism. This is a return of the problem first faced by the theory of evolution, which had surfaced quite some time before Darwin. It was only after geologists had shown that the earth was much older than previously thought that Darwin was provided with a time-span necessary for his theory to be convincing. Now there is some doubt as to whether even three to four billion years, enormous though that is, is long enough for all known species of life to have slowly evolved from the simplest living cell. As Denton again notes, "the complexity of the human brain would require eternity for its assembly in terms of our current engineering capabilities.

But just as Denton rightly argues that Darwin was not justified in jumping from his special theory to his general theory, so Denton himself is guilty of a similar jump. Showing to his satisfaction that Darwin's theory of natural selection is not an adequate explanation of evolution he believes he has undermined the theory of evolution itself, arguing for what he calls "an anti-evolutionary thesis", by which the variety of species has occurred by a fundamentally discontinuous process. But he has not clearly presented any such alternative. The theory of evolution may still leave us with many problems but this does not justify saying that it is a "theory in crisis".

The very fact that we do not yet know just how the evolution of species has occurred does not in itself disprove the idea of evolution. The reason why a geneticist such as Dobzhansky can say, "Nothing in biology makes sense except in the light of evolution" is that in the light of all current knowledge the slow evolution of all forms of life on this planet is not only more convincing than the traditional "creationist" theory, which it replaced, but it will only be superseded when a new and more convincing theory has been put forward. Denton has not produced this.

On the definition of "myth" as a controlling image or story one can say that the evolutionary theory is now an internationally held myth, which has largely displaced the Judeo-Christian "creationist" myth and it will remain a universal myth of the origins of life until a more convincing myth displaces it.

Lloyd Geering