Genome: The Autobiography of a Species in 23 Chapters

  • Matt Ridley
Fourth Estate: 1999. 752 pp. £18.99, $26
Chapter and verse: the entire contents of the 23 human chromosomes should soon be known.

Genetics, I believe, will stand alongside computing and nuclear physics as one of the outstanding areas of development by which this century will be remembered. The century started precisely with the rediscovery of Mendelism and it will finish with a first draft of the complete DNA sequence of the human genome. That remarkable catalogue of the human genes, ordered along the chromosomes to give us the Book of Man, will form the basis of most future biological and biochemical investigations of humans. The end of the Human Genome Project is the beginning of the real genetics of mankind. And this is the substantial challenge for understanding over the next century or more.

By combining the power of molecular genetics with classical population genetics and quantitative analysis, new approaches have been devised, not only for the ‘positional’ cloning of Mendelian traits whose biochemical basis was totally unknown, but also for identifying genes that contribute to the inherited susceptibility to multifactorial traits and diseases. Genes associated with nearly every Mendelian disease have been cloned, however rare the disease. But recall the great physician William Harvey, who urged us to treasure our exceptions, from which, as we now know, so much can be learnt. There is an exciting story to be told about genetics in the genomic era, but that is not to be found in Matt Ridley's book.

His title leads to the expectation that these exciting developments in genetics will be revealed to the general reader. However, in the preface we are told that “this is not a book about the human genome project”, but instead “a book about what the project has found”. The book is based on an intriguing idea, namely, to progress through the chromosomes chapter by chapter, using in each an example to illustrate what the genome reveals when it is properly read and interpreted. Ridley, a professional science writer and journalist, has, however, followed a common journalist's pathway and selected a collection of topics that he presumes will interest the reader whether or not they are relevant to his professed goal. Too many of these topics, such as sexual evolution, IQ, personality, stress and its relationship to immunity, ageing, memory and even, finally, free will, are simply not yet ready to yield to modern genetic approaches. They are mostly a basis for largely unsubstantiated speculation described in a way that could have been written without any reference to what the genome has to tell us.

Chromosome 1, the largest, is, according to Ridley, apparently empty, although a discussion of the rhesus blood groups might have been of interest. Chromosome 2 is used only as a vehicle for comparing Homo sapiens with the chimpanzee, the first of many “mind boggling” comparisons, in this case because of Ridley's apparent surprise that it may take only a relatively small number of differences in the DNA code to distinguish man from chimpanzees. Huntington's disease occupies chromosome 4. Certainly, it is an interesting story, but hardly, as the author claims, the most talked about genetic disease.

Given my own long-standing involvement with the HLA system and the genetics of the immune response, such topics would have been my natural choice for chromosome 6. But immunology, in spite of its enormous interest and dramatic development, hardly gets a mention, even in the discussion of asthma, and the only reference to the HLA system is in relation to the rather questionable data on mating preferences. Ridley's chromosome 6 is devoted to the somewhat flimsy evidence for a gene with a possible influence on IQ.

There are some good chapters. The relationship between the apoE lipoprotein gene and Alzheimer's disease is well told and the chapter on BSE is also good. Ridley even mentions James Parry, the geneticist in Oxford whose sheep pedigrees told the correct story about scrapie, as he explained to me when I first came to Oxford in 1970, and which no one believed. A good chapter on eugenics is seriously marred by the fact that it draws the analogy between screening for Down's syndrome and Nazism. Even negative eugenics is hardly applicable to Down's syndrome, and the importance of doing genetic screening only if benefit can be derived from it is hardly mentioned.

Historical treatments of scientific discoveries are a good vehicle for presenting the underlying science, but not when they are as abbreviated and distorted as they often are in Genome. There were, for example, several co-discoverers of the p53 gene; and the molecular biology of prions was uncovered by Charles Weissmann and his colleagues. The story of Gregor Mendel's discoveries is described as though they appeared from nowhere, and ignores the evidence that they were stimulated by his abbot's interest in uncovering the basis for the animal and plant breeding used in the monastery's farms. It was the theoretical physicist George Gamow, not Francis Crick, who first suggested codes relating DNA to protein. I still remember when, as a young mathematical geneticist, I sought Crick's advice about problems I might investigate in molecular biology, and he suggested that I explore the mathematics of overlapping codes. Fortunately and correctly, I did not see how my mathematics could help to provide a solution to the coding problem, which eventually came entirely from experimental approaches.

Style is, I suppose, a matter of personal preference. “Now I tell you again Dear Reader” somehow does not, to my mind, match the topic of ‘genome’. Suddenly, towards the middle of the book, we are told “the human genome project is founded upon a fallacy”! He has clearly not yet explained the importance of human variation, which underlies any explanation, for example, of the balance between nature and nurture. Perhaps it is this he is referring to when he says, “the tension between universal characteristics of the human race and particular features of individuals is what the genome is all about”. There is also the occasional strange, throwaway sentence: “But then judges were never very good at science” seems a remarkably injudicious comment, and I wonder on what basis he makes this extraordinary suggestion.

Ridley has written well in the past on evolutionary topics, and is clearly capable of writing in a stimulating way for the general reader. Perhaps in future he would do best to stick to topics involving evolutionary ideas, where he is most at home. If this book kindles an interest in the genome and what can be found out using modern genetic approaches, then perhaps it is doing a service. But if you want a serious and challenging discussion of what genetics and the genome can tell us about humans, I am afraid you must look elsewhere.