The Extended Phenotype
Richard Dawkins is the first holder of Oxford’s newly endowed Charles Simonyi Professorship of Public Understanding of Science. Born in Nairobi of British parents, Richard Dawkins was educated at Oxford and did his doctorate under the Nobel prize-winning ethologist Niko Tinbergen. From 1967 to 1969 he was an Assistant Professor at the University of California at Berkeley, then he returned to Oxford as University Lecturer (later Reader) and a Fellow of New College, before taking up his present position in 1995.
Richard Dawkins’s bestselling books have played a significant role in the renaissance of science book publishing for a general audience. The Selfish Gene (1976; second edition 1989) was followed by The Extended Phenotype (1982), The Blind Watchmaker (1986), River Out of Eden (1995), Climbing Mount Improbable (1996), and Unweaving the Rainbow (1998). In 1991 he gave the Royal Institution Christmas Lectures. He has won many literary and scientific awards, including the 1987 Royal Society of Literature Award, the 1990 Michael Faraday Award of the Royal Society, the 1994 Nakayama Prize for Human Science, and the 1997 International Cosmos Prize.
Daniel Dennett is Distinguished Arts and Sciences Professor of Philosophy, and Director of the Center for Cognitive Studies at Tufts University. His first book, Content and Consciousness, appeared in 1969, followed by Brainstorms (1978), Elbow Room (1984), The Intentional Stance (1987), Consciousness Explained (1991), Darwin’s Dangerous Idea (1995), and Kinds of Minds (1996). He co-edited The Mind’s I with Douglas Hofstadter in 1981. He is the author of over a hundred scholarly articles on various aspects of the mind, published in journals ranging from Artificial Intelligence and Behavioural and Brain Sciences to Poetics Today and the Journal of Aesthetics and Art Criticism. His most recent book is Brainchildren: Essays on Designing Minds (MIT Press and Penguin, 1998).
The Extended Phenotype
The Long Reach of the Gene
Richard Dawkins
With a new afterword by Daniel Dennett
Oxford University Press, Great Clarendon Street, Oxford OX2 6DP
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© Richard Dawkins 1982, 1999
Afterword © Daniel Dennett 1999
First published 1982
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Preface
The first chapter does some of the work of a Preface, in explaining what the book does and does not set out to accomplish, so I can be brief here. It is not a textbook, nor an introduction to an established field. It is a personal look at the evolution of life, and in particular at the logic of natural selection and the level in the hierarchy of life at which natural selection can be said to act. I happen to be an ethologist, but I hope preoccupations with animal behaviour will not be too noticeable. The intended scope of the book is wider.
The readers for whom I am mainly writing are my professional colleagues, evolutionary biologists, ethologists and sociobiologists, ecologists, and philosophers and humanists interested in evolutionary science, including, of course, graduate and undergraduate students in all these disciplines. Therefore, although this book is in some ways the sequel to my previous book, The Selfish Gene, it assumes that the reader has professional knowledge of evolutionary biology and its technical terms. On the other hand it is possible to enjoy a professional book as a spectator, even if not a participant in the profession. Some laypeople who read this book in draft have been kind enough, or polite enough, to claim to have liked it. It would give me great satisfaction to believe them, and I have added a glossary of technical terms which I hope may help. I have also tried to make the book as near as possible to being enjoyable to read. The resulting tone may possibly irritate some serious professionals. I very much hope not, because serious professionals are the primary audience to whom I wish to speak. It is as impossible to please everybody in literary style as it is in any other matter of taste, and styles that give the most positive pleasure to some people are often the most annoying to others.
Certainly the tone of the book is not conciliatory or apologetic—such is not the way of an advocate that sincerely believes in his case—and I must pack all apology into the Preface. Some of the earlier chapters reply to criticisms of my previous book, which might recur in response to the present one. I am sorry that this is necessary, and I am sorry if a note of exasperation creeps in from time to time. I trust, at least, that my exasperation remains good humoured. It is necessary to point to past misunderstandings and try to forestall their repetition, but I would not wish to give an aggrieved impression that misunderstanding has been widespread. It has been confined to numerically very limited quarters, but in some cases rather vocal ones. I am grateful to my critics for forcing me to think again about how to express difficult matters more clearly.
I apologize to readers who may find a favourite and relevant work missing from the bibliography. There are those capable of comprehensively and exhaustively surveying the literature of a large field, but I have never been able to understand how they manage it. I know that the examples I have cited are a small subset of those that could have been cited, and are sometimes the writings or recommendations of my friends. If the result appears biased, well, of course it is biased, and I am sorry. I think nearly everybody must be somewhat biased in this kind of way.
A book inevitably reflects the current preoccupations of the author, and these preoccupations are likely to have been among the topics of his most recent papers. When those papers are so recent that it would be an artificial contrivance to change the words, I have not hesitated to reproduce a paragraph almost verbatim here and there. These pa
ragraphs, which will be found in Chapters 4, 5, 6 and 14, are an integral part of the message of this book, and to omit them would be just as artificial as to make gratuitous changes in their wording.
The opening sentence of Chapter 1 describes the book as a work of unabashed advocacy but, well, perhaps I am just a little bit abashed! Wilson (1975, pp. 28–29) has rightly castigated the ‘advocacy method’ in any search for scientific truth, and I have therefore devoted some of my first chapter to a plea of mitigation. I certainly would not want science to adopt the legal system in which professional advocates make the best case they can for a position, even if they believe it to be false. I believe deeply in the view of life that this book advocates, and have done so, at least in part, for a long time, certainly since the time of my first published paper, in which I characterized adaptations as favouring ‘the survival of the animal’s genes …’ (Dawkins 1968). This belief—that if adaptations are to be treated as ‘for the good of’ something, that something is the gene—was the fundamental assumption of my previous book. The present book goes further. To dramatize it a bit, it attempts to free the selfish gene from the individual organism which has been its conceptual prison. The phenotypic effects of a gene are the tools by which it levers itself into the next generation, and these tools may ‘extend’ far outside the body in which the gene sits, even reaching deep into the nervous systems of other organisms. Since it is not a factual position I am advocating, but a way of seeing facts, I wanted to warn the reader not to expect ‘evidence’ in the normal sense of the word. I announced that the book was a work of advocacy, because I was anxious not to disappoint the reader, not to lead her on under false pretences and waste her time.
The linguistic experiment of the last sentence reminds me that I wish I had had the courage to instruct the computer to feminize personal pronouns at random throughout the text. This is not only because I admire the current awareness of the masculine bias in our language. Whenever I write I have a particular imaginary reader in mind (different imaginary readers oversee and ‘filter’ the same passage in numerous successive revisions) and at least half my imaginary readers are, like at least half my friends, female. Unfortunately it is still true in English that the unexpectedness of a feminine pronoun, where a neutral meaning is intended, seriously distracts the attention of most readers, of either sex. I believe the experiment of the previous paragraph will substantiate this. With regret, therefore, I have followed the standard convention in this book.
For me, writing is almost a social activity, and I am grateful to the many friends who have, sometimes unwittingly, participated through discussion, argument and moral support. I cannot thank them all by name. Marian Stamp Dawkins has not only provided sensitive and knowledgeable criticism of the whole book in several drafts. She has also kept me going by believing in the project even through the times when I lost my own confidence. Alan Grafen and Mark Ridley, officially my graduate students, really, in their different ways, my mentors and guides through difficult theoretical territory, have influenced the book immeasurably. In the first draft their names seemed to creep in on almost every page, and it was only the pardonable grumblings of a referee that compelled me to banish to the Preface my acknowledgment of debt to them. Cathy Kennedy manages to combine close friendship for me with deep sympathy for my bitterest critics. This has put her in a unique position to advise me, especially over the earlier chapters which attempt to reply to criticism. I fear that she will still not like the tone of these chapters, but such improvement as there may be is largely due to her influence and I am very grateful to her.
I was privileged to have the first draft criticized in its entirety by John Maynard Smith, David C. Smith, John Krebs, Paul Harvey, and Ric Charnov, and the final draft owes much to all of them. In all cases I acted on their advice, even if I did not always take it. Others kindly criticized chapters in their own special fields: Michael Hansell the chapter on artefacts, Pauline Lawrence that on parasites, Egbert Leigh that on fitness, Anthony Hallam the section on punctuated equilibria, W. Ford Doolittle that on selfish DNA, and Diane De Steven botanical sections. The book was finished at Oxford, but begun during a visit to the University of Florida at Gainesville on a sabbatical leave kindly granted by the University of Oxford and the Warden and Fellows of New College. I am grateful to my many Floridan friends for giving me such a pleasant atmosphere in which to work, especially Jane Brockmann, who also provided helpful criticism of preliminary drafts, and Donna Gillis, who also did much of the typing. I benefited, too, from a month’s exposure to tropical biology as the grateful guest of the Smithsonian Institution in Panama during the writing of the book. Finally, it is a pleasure once again to thank Michael Rodgers, formerly of Oxford University Press and now of W. H. Freeman and Company, a ‘K-selected’ editor who really believes in his books and is their tireless advocate.
Oxford
Richard Dawkins
June 1981
Note to Oxford Paperback Edition
I suppose most scientists—most authors—have one piece of work of which they would say: It doesn’t matter if you never read anything else of mine, please at least read this. For me, it is The Extended Phenotype. In particular, the last four chapters constitute the best candidate for the title ‘innovative’ that I have to offer. The rest of the book does some necessary sorting out on the way. Chapters 2 and 3 are replies to criticisms of the now widely accepted ‘selfish gene’ view of evolution. The middle chapters deal with the ‘units of selection’ controversy currently fashionable among philosophers of biology, taking the gene’s-eye view; perhaps the most useful contribution here is the ‘Replicators and Vehicles’ distinction. My intention was that this piece of sorting out should put paid to the whole controversy once and for all!
As for the extended phenotype proper, I have never seen any alternative to placing it at the end of the book. Nevertheless, this policy has a disadvantage. The earlier chapters inevitably draw attention to the general ‘units of selection’ issue, and away from the more novel idea of the extended phenotype itself. It is for this reason that I have dropped the original subtitle, ‘The Gene as the Unit of Selection’, from this edition. The replacement, ‘The Long Reach of the Gene’, captures the idea of the gene as the centre of a web of radiating power. The book is otherwise unchanged apart from minor corrections.
Oxford
Richard Dawkins
May 1989
Contents
Acknowledgements
1 Necker Cubes and Buffaloes
2 Genetic Determinism and Gene Selectionism
3 Constraints on Perfection
4 Arms Races and Manipulation
5 The Active Germ-Line Replicator
6 Organisms, Groups and Memes: Replicators or Vehicles?
7 Selfish Wasp or Selfish Strategy?
8 Outlaws and Modifiers
9 Selfish DNA, Jumping Genes, and a Lamarckian Scare
10 An Agony in Five Fits
11 The Genetical Evolution of Animal Artefacts
12 Host Phenotypes of Parasite Genes
13 Action at a Distance
14 Rediscovering the Organism
Afterword by Daniel Dennett
References
Further Reading
Glossary
Author Index
Subject Index
Acknowledgements
pp. 141–142 ‘The Fifth Philosopher’s Song’ from The Collected Poetry of Aldous Huxley edited by Donald Watt. Copyright © 1971 by Laura Huxley. Reproduced by permission of Mrs. Laura Huxley and Chatto & Windus Ltd, also by permission of Harper & Row, Publishers, Inc. (USA)
p. 16 ‘McAndrew’s Hymn’ by Richard Kipling. Extract reproduced by permission of Doubleday & Company Inc.
The Extended Phenotype
1 Necker Cubes and Buffaloes
This is a work of unabashed advocacy. I want to argue in favour of a particular way of looking at animals and plants, and a particular way of wondering why they do
the things that they do. What I am advocating is not a new theory, not a hypothesis which can be verified or falsified, not a model which can be judged by its predictions. If it were any of those things, I agree with Wilson (1975, p. 28) that the ‘advocacy method’ would be inappropriate and reprehensible. But it is not any of those things. What I am advocating is a point of view, a way of looking at familiar facts and ideas, and a way of asking new questions about them. Any reader who expects a convincing new theory in the conventional sense of the word is bound to be left, therefore, with a disappointed ‘so what?’ feeling. But I am not trying to convince anyone of the truth of any factual proposition. Rather, I am trying to show the reader a way of seeing biological facts.
There is a well-known visual illusion called the Necker Cube. It consists of a line drawing which the brain interprets as a three-dimensional cube. But there are two possible orientations of the perceived cube, and both are equally compatible with the two-dimensional image on the paper. We usually begin by seeing one of the two orientations, but if we look for several seconds the cube ‘flips over’ in the mind, and we see the other apparent orientation. After a few more seconds the mental image flips back and it continues to alternate as long as we look at the picture. The point is that neither of the two perceptions of the cube is the correct or ‘true’ one. They are equally correct. Similarly the vision of life that I advocate, and label with the name of the extended phenotype, is not provably more correct than the orthodox view. It is a different view and I suspect that, at least in some respects, it provides a deeper understanding. But I doubt that there is any experiment that could be done to prove my claim.
The phenomena that I shall consider—coevolution, arms races, manipulation of hosts by parasites, manipulation of the inanimate world by living things, economic ‘strategies’ for minimizing costs and maximizing benefits—are all familiar enough, and are already the subject of intensive study. Why, then, should the busy reader bother to go on? It is tempting to borrow Stephen Gould’s winningly ingenuous appeal at the beginning of a more substantial volume (1977a) and simply say, ‘Please read the book’ and you will find out why it was worth bothering to do so. Unfortunately I do not have the same grounds for confidence. I can only say that, as one ordinary biologist studying animal behaviour, I have found that the viewpoint represented by the label ‘extended phenotype’ has made me see animals and their behaviour differently, and I think I understand them better for it. The extended phenotype may not constitute a testable hypothesis in itself, but it so far changes the way we see animals and plants that it may cause us to think of testable hypotheses that we would otherwise never have dreamed of.