Profile Books, 2009
Reviewed by Michael Colebrook
It is very appropriate that this book should have appeared in Darwin’s year (2009) and I started to write this review on the 150th anniversary day of the publication of The Origin of Species.
The author is a biochemist and he deals with aspects of the evolutionary story at the molecular level that were quite unknown in Darwin’s day. It does present a problem for the reader in that some knowledge of chemistry and basic biology is an asset in following the stories he tells. But he also tells his stories very well, with the minimum of technical language and no formulae!
The book opens with a necessarily speculative but very convincing argument that life started in one of the forms of submarine hydrothermal vents. These are known as alkaline vents in contrast to the better know acidic ‘black smokers’. Both the physical structure and the chemical environment of these vents provide definite possibilities for the emergence of living organisms.
There is a problem in the field of molecular evolution in that there can be no direct fossil record of biochemical systems. Everything has to be based on inference from what is going on in organisms that are alive today. Nevertheless, it is clear that, at the biochemical level, many of the processes and systems found in organisms living today had their origin in the very earliest phases of the evolutionary story. We are given a glimpse of what had to be happening during the long, long period of evolutionary history, of about three thousand million years, when the only living creatures were the bacteria and the single celled eukaryotes.
A good example is the Krebs cycle. This is a remarkably complicated system involved in the production of the energy needed for the functioning of just about every cell of just about every organism that has ever existed (see box). As the author states: “There is a marvellous unity to the world of the cell, which gives a deep sense of connection and fellowship with the world around.” Another example is that the two main proteins, myosin and actin, which are involved in the muscle systems of just about all the multi-cellular animals from jelly fish to insects to humans, are also found in the intracellular systems of all eukaryote organisms.
The chapter on sex includes a refreshing emphasis on the role of recombination—as opposed to the more common stress on mutation—in the emergence of genetic variation and its role in evolution by natural selection. Recombination involves a rearrangement of the sets of existing genes located in specific chromosomes. The result being that offspring inherit an essentially random mix of the genes of their parents. A lot can go on even without mutation.
The author goes on to describe a number of systems at the biochemical level but he avoids the obvious trap of reductionism. We come away with a feeling of the great antiquity of the origins of the systems. Altogether an illuminating and valuable contribution to the evolutionary story.