on 2 June 2013
This is an interesting book. As a lay person interested in evolution I have always been concerned whether simple selection of mutant variants of coding genes would 'be enough' to account for evolutionary change and diversity. This book and the 'silent gene' theory it describes seemed to go some way to explain this problem. The idea of a reservoir of non-coding genes happily mutating and not being deselected by the environment until one day they start coding for proteins seems highly plausible. Little attention was paid, however, to the statistical probability that a useful gene or part of a gene could be created this way (I remember the calculations made by the creationists regarding the possibility of useful amino acid sequences arriving by pure chance). The descriptions of complex interactions of genetic material was interesting and highlighted the difference between simply decoding genomes and actually understanding what they do. The 'A' level biology image of a string of DNA coding for proteins and not doing much else seems a long way off after reading this. The neo-Darwinist popular science writers seem to me to be content with this huge simplification of the roles of DNA and this book goes some way to highlight this. I don't think that silent gene theory is really a new theory of evolution, to me it just provides a more plausible mechanism for phenotypic variety to be introduced into an organism. I suspect that as the mind-bogglingly complex interactions of genetic material becomes better understood then silent gene theory (or something like it) will become part of accepted evolutionary theory. Overall,as stated at the beginning, an interesting read, written with some of the humility that Darwin displayed in the Origin.
on 10 May 2012
Darwin wrote that variation within species must be present before natural selection can act. But natural selection reduces variation in favour of an optimum type. So where does variation come from? Warwick Collins looked for much of his life for an independent source of variation, and came to the conclusion that it was only possible if a special class of genes were present, which he called silent genes. Such genes did not code for physical characteristics and therefore could not be "seen" by natural selection acting on the physical characteristics of the organism. Existing beneath the radar of natural selection, they could mutate freely over time. Eventually they could be switched on, generating exotic new variations. Collins found, to his delight, that such genes were present in vast numbers, and that the evidence shows that the great majority of new coding genes emerge from the silent genes, exactly as his theory proposed. His theory also suggested that, if silent genes generated the variation that drove evolution, the most complex species would tend to have the highest ratios of silent genes. This prediction has also been strongly confirmed across evolutionary systems. If Collins is right, silent genes drive evolution, and natural selection is a secondary process which occurs after variation has been generated. I agree with the cover quote on the book by the great physicist Freeman Dyson. If Darwin were alive today, he would have liked this theory.
on 11 May 2012
I hope everyone who reads this book tells their friends about it. Only once in several generations does one encounter a work which challenges directly one of the greatest scientific certainties of the day -- in this case, the idea that evolution is driven by natural selection. Collins is an admirer of Darwin, and if anything Darwin's contribution is expanded with this new theory. The justification for Darwin was that he knew nothing about genes and constructed the best theory that he could. That doesn't apply to the prevailing school of neo-Darwinism. It will be interesting to see how the evolutionary establishment reacts to the book. Meanwhile, for the open-minded reader, this is an exhilarating read.