Richard Dawkins: books: The Extended Phenotype
  |
Definition | Reviews | Related Links | Endorsements | Selected Quotes |
 |
The
Extended Phenotype:
|
- Book info from the publisher Oxford University Press
- Order this book from the online bookstore amazon.com (USA)
- Order this book from the online bookstore amazon.co.uk (UK)
| Definition from Book |  |
Extended Phenotype: All effects of a gene upon the world. As always, 'effect' of a gene is understood as meaning in comparison with its alleles. The conventional phenotype is a special case in which the effects are regarded as being confined to the individual body in which the gene sits. In practice it is convenient to limit 'extended phenotype' to cases where the effects influence the survival chances of the gene, positively or negatively.
| Reviews | |
by Deron Stewart from Church of Virus
| Endorsements | |
"The Extended Phenotype is the sequel to
The Selfish Gene. Although Dawkins has aimed his
second book primarily at professional biologists, he
writes so clearly that is could be understood by anyone
prepared to make the effort."
J. Maynard Smith, London Review of
Books
"This entertaining and thought-provoking book ...
is an excellent illustration of why the study of
evolution is in such an exciting ferment these
days."
Science
"Dawkins is quite incapable of being boring. His
clarity and vivacity as a writer are so many orders of
magnitude removed from many of us as to be desperately
enviable ... this characteristically brilliant and
stimulating book ... is original and provocative
throughout and immensely enjoyable."
G. A. Parker, Heredity
"The extended phenotype is certainly a big idea
and it is pressed hard in dramatic language."
Sydney Brenner, Nature
"This may be the most important book on
evolutionary biology in the last decade or two"
Antoni Hoffman
| Selected Quotes and Excerpts | |
Excerpt from 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. ... I have added a glossary of technical terms which I hope may help.
Excerpts from Chapter 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.
One feature of life in this world which, like sex, we have taken for granted and maybe should not, is that living matter comes in discrete packages called organisms. In particular, biologists interested in functional explanation usually assume that the appropriate unit for discussion is the individual organism. To us,'conflict' usually means conflict between organisms, each one striving to maximize its own individual 'fitness'. We recognize smaller units such as cells and genes, and larger units such as populations, societies and ecosystems, but there is no doubt that the individual body, as a discrete unit of action, exerts a powerful hold over the minds of zoologists, especially those interested in the adaptive significance of animal behaviour. One of my aims in this book is to break that hold. I want to switch emphasis from the individual body as focal unit of functional discussion. At the very least I want to make us aware of how much we take for granted when we look at life as a collection of discrete individual organisms.
The thesis that I shall support is this. It is legitimate to speak of adaptations as being 'for the benefit of' something, but that something is best not seen as the individual organism. It is a smaller unit which I call the active, germ-line replicator. The most important kind of replicator is the 'gene' or small genetic fragment. Replicators are not, of course, selected directly, but by proxy; they are judged by their phenotypic effects. Although for some purposes it is convenient to think of these phenotypic effects as being packaged together in discrete 'vehicles' such as individual organisms, this is not fundamentally necessary. Rather, the replicator should be thought of as having extended phenotypic effects, consisting of all its effects on the world at large, not just its effects on the individual body in which it happens to be sitting.
To return to the analogy of the Necker Cube, the mental flip that I want to encourage can be characterized as follows. We look at life and begin by seeing a collection of interacting individual organisms. We know that they contain smaller units, and we know that they are, in turn, parts of larger composite units, but we fix our gaze on the whole organisms. Then suddenly the image flips. The individual bodies are still there; they have not moved, but they seem to have gone transparent. We see through them to the replicating fragments of DNA within, and we see the wider world as an arena in which these genetic fragments play out their tournaments of manipulative skill. Genes manipulate the world and shape it to assist their replication. It happens that they have 'chosen' to do so largely by moulding matter into large multicellular chunks which we call organisms, but this might not have been so. Fundamentally, what is going on is that replicating molecules ensure their survival by means of phenotypic effects on the world. It is only incidentally true that those phenotypic effects happen to be packaged up into units called individual organisms.
