The Edge of Evolution (Review)

Book review: 'The Edge of Evolution – The Search for the Limits of Darwinism' by Michael J. Behe

Michael Behe is Professor of Biological Science at Lehigh University in the USA. In 1996 he published Darwin's Black Box, a book in which he argued for the idea that some biological structures were so complex that they could not have evolved in typical Darwinian fashion and must therefore be the result of 'intelligent design'. His arguments were an advance in sophistication for the creationists who soon adopted intelligent design as a major support for creation by a god.

In 'The Edge of Evolution' Behe marshals other arguments for intelligent design but is careful to make it clear that he is not specifying the nature of the 'intelligence' --- neither god nor some form of supreme being. Behe leaves that question to others. His primary concern is to raise questions that are difficult for science (and particularly Darwinian-oriented science) to answer.

The core of Behe's critique of Darwinian science is that random mutation and natural selection cannot explain much about the evolution of life (he accepts the Darwinian idea of 'common descent' from earlier forms of life). These Darwinian processes, Behe concedes, can explain variety among individuals and species—and perhaps among genus, family or even order (these are at the edge of evolution, says Behe)—but cannot account for the 'fine-tuning' of the rest of the biological world.

It would be a mistake to write Behe off as 'unscientific'. He is knowledgeable in his field (which this reviewer is not) and is probably at the cutting edge of developments in molecular and cellular biology. So, having made his case for design in a range of life forms, Behe invokes his scientific position in asking how far intelligent design can extend: 'Does design extend even further into life, into the orders or even families of vertebrate classes? To such creatures as bats, whales and giraffes? ... I would guess the answer is almost certainly yes. But at this point our reliable molecular data run out, so a reasonably firm answer will have to await further research. Given the pace of modern science, we shouldn't have to wait too long' (p. 199).

It is not possible in the space of a review to represent the detailed arguments advanced by Behe to illustrate the limits of random mutation and natural selection in explaining all of life's evolutionary phenomena. The book itself is 'a good read', particularly if the reader has education in biology beyond the secondary school level, and Behe is a clear communicator of some fairly complex and difficult ideas. He makes frequent use of analogies to assist the reader to grasp the points he is making. While such analogies are helpful for the comprehension of difficult concepts, one wonders if the kind of thinking involved in analogies is itself a barrier to a different way of understanding these complex biological phenomena. A paradigm shift in thinking may be needed before scientists will be able to unravel the mysteries with which they are grappling.

Random mutation is the key concept that preoccupies Behe as he tries to ascertain how much of biological variation can be explained by Darwinian principles for evolution. A substantial part of his writing is devoted to illustrating that 'there is strong evidence that random mutation is extremely limited' (p. 3). Interestingly, although Behe makes a comprehensive case for his view that 'mathematical probabilities and biochemical structures cannot support Darwinism's randomness, except at the margins of evolution' he immediately seems to deny his own 'intelligent design' conclusion with the caveat that 'as we seek to find the line marking the edge of randomness, there is no need to infer design' (p. 8). So, although he concludes that an intelligent design is at work, he acknowledges that it is not necessary to come to that conclusion.

Malaria and its resistance to various antibiotics is a central part of Behe's evidence of the inadequacy of random mutation and natural selection to explain all evolution. The huge numbers of the malaria parasite, the large numbers of humans who have 'hosted' the parasite, and the great stretches of time over which the parasite might evolve (and its resistance to chloroquine) are part of the calculations involved in examining the role of random mutation in this organism. Humans, by comparison, must evolve more slowly. The complexity of sickle cell trait as a protection against malaria, the evidence of evolution in yeasts, and the development in some fish of 'anti-freeze' properties enabling them to survive in icy waters—all are described and discussed in detail. Darwinian evolution is given its due; but Behe writes that random variation fails to explain the basic features of biology, the 'sophisticated molecular machinery that undergirds life: to account for that ... multiple coherent genetic mutations are needed. Now that we know what sorts of mutations can happen to DNA, and what random changes can produce, we can begin to do the math to find the edge of evolution with some precision. What we'll discover is something quite basic, yet heresy to Darwinists: Most mutations that built the great structures of life must have been nonrandom' (p. 83).

There is no doubt in my mind that Behe is confronting neo-Darwinian evolutionary science with questions that are difficult to answer, given the present state of knowledge in the field. However, it seems to me that this only illustrates the limits of the science to date. Perhaps Darwinian concepts, sharpened through recent discoveries to do with DNA and related biology, are only the start of our understanding. Random mutation and natural selection may be insufficient in the long run, first building blocks in a much more complex science that itself is still evolving. In the meantime, however, as Behe himself has said, there is no need to infer 'an intelligence' that has produced the phenomena of life. Nevertheless, Behe is committed to 'design', even if its nature is obscure. He writes (p. 170): 'If a cellular feature has some discernible function, and if it seems to be beyond what is biologically reasonable to expect by chance, then with varying degrees of confidence we are justified in chalking it up to design.'

Just as physics underwent a transformative shift with Einstein's theory of relativity, so biology is perhaps now in need of a new way of conceptualising the data into a framework of understanding that will resolve some of the questions that Michael Behe asks. To admit our ignorance while we hope for such a scientific breakthrough is no shame. The questions must be asked. We need not call on supernatural explanations to account for answers we do not have.

1115 words

Reviewed by Ian Edward Macindoe