The Extended Phenotype: The Long Reach of the Gene (Popular Science) (3 page)

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.

We do not at present appreciate the organism for the remarkable phenomenon it is. We are accustomed to asking, of any widespread biological phenomenon, ‘What is its survival value?’ But we do not say, ‘What is the survival value of packaging life up into discrete units called organisms?’ We accept it as a given feature of the way life is. As I have already noted, the organism becomes the automatic subject of our questions about the survival value of other things: ‘In what way does this behaviour pattern benefit the individual doing it? In what way does this morphological structure benefit the individual it is attached to?’

It has become a kind of ‘central theorem’ (Barash 1977) of modern ethology that organisms are expected to behave in such a way as to benefit their own inclusive fitness (Hamilton 1964a,b), rather than to benefit anyone, or anything, else. We do not ask in what way the behaviour of the left hind leg benefits the left hind leg. Nor, nowadays, do most of us ask how the behaviour of a group of organisms, or the structure of an ecosystem, benefits that group or ecosystem. We treat groups and ecosystems as collections of warring, or uneasily cohabiting, organisms; and we treat legs, kidneys, and cells as cooperating components of a single organism. I am not necessarily objecting to this focus of attention on individual organisms, merely calling attention to it as something that we take for granted. Perhaps we should stop taking it for granted and start wondering about the individual organism, as something that needs explaining in its own right, just as we found sexual reproduction to be something that needs explaining in its own right.

At this point an accident of the history of biology necessitates a tiresome digression. The prevailing orthodoxy of my previous paragraph, the central dogma of individual organisms working to maximize their own reproductive success, the paradigm of ‘the selfish organism’, was Darwin’s paradigm, and it is dominant today. One might imagine, therefore, that it had had a good run for its money and should, by now, be ripe for revolution, or at least constitute a solid-enough bastion to withstand iconoclastic pinpricks such as any that this book might deliver. Unfortunately, and this is the historical accident I mentioned, although it is true that there has seldom been any
temptation to treat units smaller than the organism as agents working for their own benefit, the same has not always been true of larger units. The intervening years since Darwin have seen an astonishing retreat from his individual-centred stand, a lapse into sloppily unconscious group-selectionism, ably documented by Williams (1966), Ghiselin (1974a) and others. As Hamilton (1975a) put it, ‘… almost the whole field of biology stampeded in the direction where Darwin had gone circumspectly or not at all’. It is only in recent years, roughly coinciding with the belated rise to fashion of Hamilton’s own ideas (Dawkins 1979b), that the stampede has been halted and turned. We painfully struggled back, harassed by sniping from a Jesuitically sophisticated and dedicated neo-group-selectionist rearguard, until we finally regained Darwin’s ground, the position that I am characterizing by the label ‘the selfish organism’, the position which, in its modern form, is dominated by the concept of inclusive fitness. Yet it is this hard-won fastness that I may seem to be abandoning here, abandoning almost before it is properly secured; and for what? For a flickering Necker Cube, a metaphysical chimera called the extended phenotype?

No, to renounce those gains is far from my intention. The paradigm of the selfish organism is vastly preferable to what Hamilton (1977) has called ‘the old, departing paradigm of adaptation for the benefit of the species’. ‘Extended phenotype’ is misunderstood if it is taken to have any connection with adaptation at the level of the group. The selfish organism, and the selfish gene with its extended phenotype, are two views of the same Necker Cube. The reader will not experience the conceptual flip-over that I seek to assist unless he begins by looking at the right cube. This book is addressed to those that already accept the currently fashionable selfish-organism view of life, rather than any form of ‘group benefit’ view.

I am not saying that the selfish organism view is necessarily wrong, but my argument, in its strong form, is that it is looking at the matter the wrong way up. I once overheard an eminent Cambridge ethologist say to an eminent Austrian ethologist (they were arguing about behaviour development): ‘You know, we really agree. It is just that you
say
it wrong.’ Gentle ‘individual selectionist’, we really do almost agree, at least in comparison to the group selectionists. It is just that you
see
it wrong!

Bonner (1958), discussing single-celled organisms, said ‘… what special use to these organisms are nuclear genes? How did they arise by selection?’ This is a good example of the kind of imaginative, radical question that I think we ought to ask about life. But if the thesis of this book is accepted, the particular question should be turned upside down. Instead of asking of what use nuclear genes are to
organisms
, we should ask why
genes
chose to group themselves together in nuclei, and in organisms. In the opening lines of the same work, Bonner says: ‘I do not propose to say anything new or original in these lectures. But I am a great believer in saying familiar, well-known
things backwards and inside out, hoping that from some new vantage point the old facts will take on a deeper significance. It is like holding an abstract painting upside down; I do not say that the meaning of the picture will suddenly be clear, but some of the structure of the composition that was hidden may show itself’ (p. 1). I came across this after writing my own Necker Cube passage, and was delighted to find the same views expressed by so respected an author.

The trouble with my Necker Cubes, and with Bonner’s abstract painting, is that, as analogies, they may be too timid and unambitious. The analogy of the Necker Cube expresses my
minimum
hope for this book. I am pretty confident that to look at life in terms of genetic replicators preserving themselves by means of their extended phenotypes is at least as satisfactory as to look at it in terms of selfish organisms maximizing their inclusive fitness. In many cases the two ways of looking at life will, indeed, be equivalent. As I shall show, ‘inclusive fitness’ was defined in such a way as to tend to make ‘the individual maximizes its inclusive fitness’ equivalent to ‘the genetic replicators maximize their survival’. At least, therefore, the biologist should try both ways of thinking, and choose the one he or she prefers. But I said this was a minimum hope. I shall discuss phenomena, ‘meiotic drive’ for instance, whose explanation is lucidly written on the second face of the cube, but which make no sense at all if we keep our mental gaze firmly fixed on the other face, that of the selfish organism. Moving from my minimum hope to my wildest daydream, it is that whole areas of biology, the study of animal communication, animal artefacts, parasitism and symbiosis, community ecology, indeed all interactions between and within organisms, will eventually be illuminated in new ways by the doctrine of the extended phenotype. As is the way with advocates, I shall try to make the strongest case I can, and this means the case for the wilder hopes rather than the more cautious minimum expectations.

If these grandiose hopes are eventually realized, perhaps a less modest analogy than the Necker Cube will be pardoned. Colin Turnbull (1961) took a pygmy friend, Kenge, out of the forest for the first time in his life, and they climbed a mountain together and looked out over the plains. Kenge saw some buffalo ‘grazing lazily several miles away, far down below. He turned to me and said. “What insects are those?” … At first I hardly understood, then I realized that in the forest vision is so limited that there is no great need to make an automatic allowance for distance when judging size. Out here in the plains, Kenge was looking for the first time over apparently unending miles of unfamiliar grasslands, with not a tree worth the name to give him any basis for comparison … When I told Kenge that the insects were buffalo, he roared with laughter and told me not to tell such stupid lies …’ (pp. 227–228).

This book as a whole, then, is a work of advocacy, but it is a poor advocate
that leaps precipitately to his conclusion when the jury are sceptical. The second face of my Necker Cube is unlikely to click into clear focus until near the end of the book. Earlier chapters prepare the ground, attempt to forestall certain risks of misunderstanding, dissect the first face of the Necker Cube in various ways, point up reasons why the paradigm of the selfish individual, if not actually incorrect, can lead to difficulties.

Parts of some early chapters are frankly retrospective and even defensive. Reaction to a previous work (Dawkins 1976a) suggests that this book is likely to raise needless fears that it promulgates two unpopular ‘-isms’—‘genetic determinism’ and ‘adaptationism’. I myself admit to being irritated by a book that provokes me into muttering ‘Yes but …’ on every page, when the author could easily have forestalled my worry by a little considerate explanation early on.
Chapters 2
and
3
try to remove at least two major sources of ‘yes-buttery’ at the outset.

Chapter 4
opens the case for the prosecution against the selfish organism, and begins to hint at the second aspect of the Necker Cube.
Chapter 5
opens the case for the ‘replicator’ as the fundamental unit of natural selection.
Chapter 6
returns to the individual organism and shows how neither it, nor any other major candidate except the small genetic fragment, qualifies as a true replicator. Rather, the individual organism should be thought of as a ‘vehicle’ for replicators.
Chapter 7
is a digression on research methodology.
Chapter 8
raises some awkward anomalies for the selfish organism, and
Chapter 9
continues the theme.
Chapter 10
discusses various notions of ‘individual fitness’, and concludes that they are confusing, and probably dispensable.

Chapters 11
,
12
and
13
are the heart of the book. They develop, by gradual degrees, the idea of the extended phenotype itself, the second face of the Necker Cube. Finally, in
Chapter 14
, we turn back with refreshed curiosity to the individual organism and ask why, after all, it is such a salient level in the hierarchy of life.

Long after his death, tenacious rumours persisted that Adolf Hitler had been seen alive and well in South America, or in Denmark, and for years a surprising number of people with no love for the man only reluctantly accepted that he was dead (Trevor-Roper 1972). In the First World War a story that a hundred thousand Russian troops had been seen landing in Scotland ‘with snow on their boots’ became widely current, apparently because of the memorable vividness of that snow (Taylor 1963). In our own time myths such as that of computers persistently sending householders electricity bills for a million pounds (Evans 1979), or of well-heeled welfare-soroungers with two expensive cars parked outside their government-subsidized council houses, are familiar to the point of cliché. There are some falsehoods, or half-truths, that seem to engender in us an active desire to believe them and pass them on even if we find them unpleasant, maybe in part, perversely,
because
we find them unpleasant.

Computers and electronic ‘chips’ provoke more than their fair share of such myth-making, perhaps because computer technology advances at a speed which is literally frightening. I know an old person who has it on good authority that ‘chips’ are usurping human functions to the extent not only of ‘driving tractors’ but even of ‘fertilizing women’. Genes, as I shall show, are the source of what may be an even larger mythology than computers. Imagine the result of combining these two powerful myths, the gene myth and the computer myth! I believe that I may have inadvertently achieved some such unfortunate synthesis in the minds of a few readers of my previous book, and the result was comic misunderstanding. Happily, such misunderstanding was not widespread, but it is worth trying to avoid a repeat of it here, and that is one purpose of the present chapter. I shall expose the myth of genetic determinism, and explain why it is necessary to use language that can be unfortunately misunderstood as genetic determinism.