This recommended reading for my biology class a couple of decades ago is sometimes a crisp and fair summary of why evolution is the powerful theory that it is. Discussion is a little convoluted in places and use of terminology and discursive argument does not aid comprehension by a less expert reader. The index is good and, while the further reading could now be considered dated, the nominated authors are really timeless pillars of evolutionary biology that deserve inclusion. Overall, this is a partly out of date introduction to evolution that aims more to tick the boxes on areas of one-time controversy than to explain them simply. It is an interesting reminder of how popular science writing, including by this author, has leaped ahead in the last couple of decades. Certainly better introductions now exist. It was not always an easy read but my comments follow.
A succinct and logical comparison with creationism and transformism lays the foundation for a discussion on heredity and the mechanism of evolution. Some aspects, such as the story of Mendel's peas, may be well known to the reader and are easily skimmed. Their inclusion remains important to mount the overall case.
Introducing the mechanisms of evolution, the water gets a little muddy. Ridley spends some time extracting the theory of evolution from charges of tautology made due to the maxim of "survival of the fittest". In explaining the gradual evolution of complex eye function (p 34), one mechanism, "symbiosis", is characterised as where "the parts of a complex organ evolve separately, in different species, and are only put together later, when many of the parts have been separately perfected". I trust this fundamental misunderstanding of speciation and, for that matter of the direction of evolution as previously defined in the text, is an editing error. When the proposed mechanism of symbiosis is explained, reference is properly made to the Margulis theory of cellular evolution, but further reference back to the putative example of the complex eye is omitted. In a scholarly text, this confusion is a head-shaker for me and the factual error to be condemned.
In describing `Natural Selection in Action', Ridley works around selection at the gene level, showing why group selection probably will not work. This book was written before Dawkins's popularisation of the selfish gene theory - as a result it is less confident and clear in its expression. There is less excuse for the prosaic discussion of evolutionary constraint because an robust and elegant debate had occurred on this issue, such as through Gould and Lewontin's `Spandrels of San Marco ...', and which provided clear and unambiguous language from which the author could postulate.
Thirty years after publication, it is not surprising that the chapter `Molecular Evolution' is dated. Today the extrapolation of the molecular theories of neutralism and selectionism is less relevant, in fact the next chapter on the `Principles of Classification' sets the scene for developments since this book was published. Navel-gazing comparisons between phenetic and phylogenetic classification have been overtaken by the power of genomics and computing. The discussion of cladism is important historically, although none of these issues now cause the level of `problem' they did earlier.
The key phenomenon of speciation is introduced with the problem of the reproductive and morphological concepts and concludes that both are real and not necessarily competing. Then the adaptive and gene flow mechanisms of speciation are posited with the conclusion that both are relevant but to uncertain extents. I felt that this chapter could have been argued in more direct language and the reader would then be allowed a clearer take-home message. The second chapter on speciation assesses sympatric and allopatric speciation and the arguments against the former. The arguments were generally sound with the possible exception of why natural selection works against hybrid and heterozygous forms. I looked forward to this explanation but the example offered seemed simplistic and artificial.
`The Rates of Evolution' is a comparison of gradualism and punctuated equilibria. The facts are covered and I expect macro-mutations would be explained more clearly now due to the progress in molecular genetics. In the chapter `Macro-evolution', Ridley notes that many arguments, for example that favouring faster evolution of larger animals, can be weak. Certainly basing an argument on the contention that modern marsupials are larger than their ancestors needs to consider the Australian megafauna which became extinct in the last 100 000 years - I became very sceptical about any case based on that example.