Review - Genome
The Autobiography of a Species in 23 Chapters
by Matt Ridley
Harpercollins, 2000
Review by Maria Trochatos
Oct 16th 2001 (Volume 5, Issue 42)

Matt Ridley's Genome: The Autobiography of a Species in 23 Chapters is a fascinating read - you won't be able to put this book down. This is due partly to Ridley's engaging and accessible style, but also to the material he discusses -- the human genome, which contains the genetic history of our species. Ridley's presentation of the material is highly informative and commendably clear, given both the complexity and volume of material covered.

This book is primarily for the lay reader. Ridley begins with a 'primer' explaining how genes work. With this basic understanding in hand, the reader is equipped to follow the more detailed discussions presented in each chapter. Ridley focuses each short, easily digestible chapter on one particularly interesting gene within each chromosome. He admits that this only permits 'a whistle-stop tour of some of the more interesting sites in the genome' (p. 6), but this is more than enough to convey the significance, excitement, and potential (benefits and risks) of this knowledge.

If Genome were a movie, it'd have everything -- history, social commentary, medical drama, sex, mystery, politics, and even philosophy. In the early chapters, Ridley discusses the basis of all life on earth (DNA), the evolution of our species (traceable in the genome), and the principles of genetic inheritance. There is also a fascinating look at the correlation of genetics and linguistics. The genome carries traces of past human migrations (the impact of different environments), and this seems to correlate with linguistic data tracing these same migrations as they are highlighted in the taxonomy of modern-day languages.

There are chapters on the impact of non-genetic influences (culture, environment) on our genes, and the pleiotropic (i.e. multiple effects of multiple genes) nature of genes. There is discussion of the interplay of nature and nurture effects on IQ (both matter), and the role of genes in language acquisition. Via a discussion of the role of cortisol in the body, which is triggered by stress, Ridley demonstrates the interaction of genes with brains and bodies and the outside world: things outside us can alter the way our genes are expressed.

There is a chapter about how genetic variability is a response to exposure to infectious diseases in our evolutionary past, and another about the fatalistic nature of some genetic disorders (e.g. the incurable Huntington's chorea). In the chapter about personality, we see how various neurotransmitters may be implicated in individual personality differences (e.g. in extreme cases, too much dopamine causes schizophrenia, too little causes Parkinson's disease). The chapter on memory is actually about learning, behavior modified by experience. Memory/learning seems to involve the tightening of connections between synapses, with particular genes involved in this process (even in simple creatures like sea slugs, this occurs via habituation, sensitization and associative learning).

Sex also features. There is a chapter on sexual antagonism (at a genetic level, evolutionary 'competition' between the X and Y chromosomes) and its expression in sexual selection, as well as the possible genetic contributions to homosexuality. Another chapter is about the relative contributions of mother and father to offspring. Active genes carry either a maternal or paternal 'imprint'; one of them will be imprinted and switched on, and the other switched off. In embryos of placental animals, for example, paternal genes make the placenta; maternal genes make the brain and head. Maternally imprinted genes build the forebrain, and paternally imprinted genes build the hypothalamus and base of the brain.

There is a chapter about 'selfish' genes, excellent self-replicators which are parasitic on the genome itself, whose remnants are found in our 'junk' DNA (genes that have been suppressed, no longer active in our genome). Interestingly, junk DNA is the basis of genetic fingerprinting. One chapter explains why our cells (and, consequently, we) age and die. (It's all to do with a protein called 'telomerase' - most of the genes for producing it get switched off in the embryo, in effect setting off a stopwatch for life expectancy.) Another explains the role of homeotic 'developmental genes', which systematically govern physical development from embryo-hood onwards. The chapter titled 'Death' is about cancer. In all creatures unneeded cells are designed to stop dividing and die, according to a precise protocol. Cancer arises from a malfunction in our tumor-suppressor genes - we need genes to encourage cells to grow, for normal development, but when they don't stop growing/dividing, they become cancerous.

The more contentious chapters concern the genetic engineering of foodstuffs and genetic manipulation for the treatment of diseases such as cancer, genetic screening, and eugenics. One chapter specifically looks at the events leading to the discovery of the causes of Creutzfeldt-Jakob ('mad cow') disease, and the British government's response to the problem. In the final chapter, 'Free Will', Ridley discusses whether, given this vast genetic knowledge, we can still believe that we act freely.

While this is a small book, its scope is wide. It's not really just about genes. It does cover the latest discoveries about the human genome, but it also presents a discussion of the impact of this knowledge on our daily lives - medically, socially, environmentally, politically, and ethically. These two domains -- the scientific and the social -- are inseparable, and Ridley tries to balance his discussion between them. Ridley's assessment of, and commentary about, many of the issues arising from this newfound genetic knowledge is interesting, but I don't think everyone will agree with him. His own view (which, when I read it, made me feel somewhat uneasy about what was to follow) appears in the Foreword:

Ridley discusses some extremely divisive issues, such as benefits and risks associated with the genetic engineering of foodstuffs, genetic screening, and genetic manipulation. His approach is objective and somewhat dispassionate, but this will not be everyone's approach to such emotionally-charged issues. Here's a sample of his views: 'Cloning may well happen not because the majority approves, but because the minority acts. That, after all, was roughly what happened in the case of test-tube babies. Society never decided to allow them; it just got used to the idea…' (p. 256-257) I'm not sure about 'used to'; Down Under, this issue is still a hot potato. 'Genetic screening does not automatically lead to such drastic solutions as abortion or gene therapy.' (p. 261) No, not automatically; but people (whether rightly or wrongly) are probably already thinking about it.

It seems to me that there is much more to be said on these issues. In the chapter on genetic testing, Ridley does raise questions regarding ethical issues. Unfortunately, he doesn't adequately answer them. This is disappointing, because most of the topics discussed have deeply embedded ethical implications that would benefit from fuller treatment. Having said that, I acknowledge that Genome is not meant to be an introductory ethics text.

Some of Ridley's inferences seem too quick and too broad. For example, from the discussion of genetic sexual antagonism, he then comments that '[suddenly] it begins to make sense why relations between the human sexes are such a minefield, and why men have such vastly different interpretations of what constitutes sexual harassment from women.' (p. 115). Hmmm. Or, from his discussion of maternal and paternal imprinting of genes in offspring, he comments that the 'brain is an organ with innate gender. The evidence from the genome, from imprinted genes and genes for sex-linked behaviors, now points to this conclusion' (p. 218). Sex is not the same concept as gender (but perhaps I'm just biased on this one because I'm female.)

Nevertheless, Ridley is convincing on other points. I found myself agreeing with his refutation of some common misconceptions about genetics, especially the one that 'genes cause diseases' (rather, it is their malfunction, mutation or absence that is the problem - among other things). The reader is regularly reminded that 'GENES ARE NOT THERE TO CAUSE DISEASES'. I found myself intrigued by the various accounts of the genetic contribution to many aspects of human life. I experienced many aa-haa moments as I read Ridley's explanations of the nature of illnesses such as cancer. I was captivated by the scientific 'detective work' involved in revealing the causes of disorders such as 'mad cow' disease. I found myself persuaded by the evidence showing correlations between genetics, evolution, and linguistics. I was impressed with Ridley's account of the complex relationship of genes, body and world, and the idea that genes do not work in isolation from the 'outside world'.

As a philosopher, the issue that I'm particularly interested in is free will. I found myself curious about Ridley's response to this problem, which he does not address until the final chapter. The paradox of determinism and free will is a long-standing philosophical question with ethical, social and legal import. The fundamental problem is this. Commonsense suggests that we have free will, and are in immediate control of our behavior - hence, we are ultimately responsible for our behavior. But commonsense (and now science) also suggests that everything that happens must have a cause - hence, we are not ultimately responsible for our behavior. These two intuitions are obviously incompatible.

There are three ways to go here. We can give up free will, and concede that everything is determined by something else. As Genome clearly shows, we now know a great deal about the genetic and other determinants of behavior. However, that we have and make choices seems to discredit determinism. We might reject determinism entirely, but this isn't a good move, because if we want to say that people are responsible for their behavior, that behavior must be caused (determined) by them. Nor do we want to say that behavior is undetermined, because undetermined behavior is random - and this is also incompatible with holding people responsible. The third, middle-of-the-road approach is compatibilism, the puzzling idea that we can be both determined and free. This is Ridley's response:

Quoting another compatibilist, A. J. Ayer, Ridley suggests that determined actions involve either force or coercion by another, or a pathological compulsion of some kind. Where these constraints are absent, actions are free. Citing chaos theory, Ridley suggests that human behavior mimics chaotic systems -- neither are random, but both can be determined yet unpredictable.

Okay, so what does this all mean? What is it to be determined yet unpredictable? Rather than shed any light on the problem, this just restates the very paradox we began with in the first place. What counts as a 'force' originating in ourselves? A genetic force? We don't have any control over our genes - we just get them. What does it mean to take 'ownership' of these genetic forces, and 'express' our own determinism? Who, exactly, takes 'ownership' and does the 'expressing'? In an earlier chapter, Ridley claims that 'nobody is in charge…You are not a brain running a body…Nor are you a body running a genome…Nor are you a genome running a brain…You are all of these things at once.' (p. 152) However, everybody 'has a unique and different endogenous nature. A self.' (p. 313). So how do all the elements that causally or physically contribute to the makeup of an individual, so carefully described by Ridley, give rise to a 'self' that can break free from those very determining forces?

The truth is, like all of us, Ridley already presupposes that we have free will. As early as chapter five he comments that among the non-genetic factors that impact our genes, free will is prominent (p. 66). Ultimately, it seems to be more matter of faith than of proof. My feeling is that Ridley's treatment of the free will issue is somewhat superficial. It is more of a consolation than a solution to the problem. He is playing with words and definitions to give the impression that there isn't a problem there at all. But closer scrutiny of his explanation raises more questions than it answers. How free will is possible, despite genetic and environmental determinism, remains a mystery. (Well, at least we now know why the free will problem is a long-standing one.)

Ridley's Genome does some things better than others. However, since Ridley clearly signposts his own views, it is fairly easy to set these aside and focus on the true worth of this book, what the genome reveals about us. I highly recommend this book to anyone interested in deepening their understanding of the technicalities of genetics that underlie so many current social issues.

© 2001 Maria Trochatos. All Rights Reserved.

Maria Trochatos is a philosophy postgraduate student at Macquarie University (Sydney, Australia). Her general field of interest is philosophy of mind and cognitive science. Her specific research focuses on folk theories, and their relation to 'formal' theories of mind, biology and physics.

This review first appeared online Sept 1, 2001