- Shopping Bag ( 0 items )
A distinct voice in the nature/nurture debate, Rose's series of essays are a response to the biological reductionism of Richard Dawkins's book, The Selfish Gene (OUP, 1990), which insists that all aspects of human life are in our genes, and everything arises as a consequence of natural selection. Rose argues that life depends on the elaborate web of interactions that occur within cells, organisms, and ecosystems, and in which DNA has but one part to play.
|1||Biology, Freedom, Determinism||1|
|2||Observing and Intervening||21|
|3||Knowing What We Know||44|
|4||The Triumph of Reductionism?||73|
|5||Genes and Organisms||98|
|10||The Poverty of Reductionism||272|
|11||Envoi: Making Biology Whole Again||302|
Biology, Freedom, Determinism
Man first of all exists, encounters himself, surges up in the world -- and defines himself afterwards ... he will be what he makes of himself. Thus there is no human nature ... Man simply is. He is what he wills ... One will never be able to explain one's action by reference to a given and specific human nature -- in other words there is no determinism: man is free, man is freedom.
Jean-Paul Sartre Existentialism and Humanism
We are survival machines -- robot vehicles blindly programmed to preserve the selfish molecules known as genes.
Richard Dawkins, The Selfish Gene
A new baby stares gravely up at her mother and her entire face curls into an unmistakable smile.
Spring, and the sticky yellow and green horse-chestnut buds slowly unfurl. Courting birds flit between the trees.
Summer, and clouds of small black midges surround us as we walk the moors.
Autumn, and amid the fallen leaves of the beech wood a miniature forest of mushrooms sprouts.
An African plain: termite mounds rise skywards, inhabited by hundreds of scurrying thousands.
A coral reef: myriads of brightly striped and patterned fish dart in and out of crevices; shoals weave and turn, each individual effortlessly part of the choreographed unity of the greater whole.
A drop of pondwater: single-celled, almost transparent creatures ooze; occasionally one meets and engulfs another.
All alive. All making their individual and collective ways in the world, cooperating, competing, avoiding, living with, living off, interdependent. All the present-day products of some four billion years of evolution, of the continued working-out of the great natural experiments that the physical and chemical conditions of planet Earth have made possible, perhaps inevitable. For every organism, a lifeline -- its own unique trajectory in time and space, from birth to death.
The sheer scale, diversity and volume of life on Earth surpasses the imagination. Take a square metre of European or North American forest and slice off the top 15 centimetres of soil, and you will find, among numerous other life forms, as many as 6 million tiny worms -- nematodes -- perhaps 200 different species. It is possible that there are as many as 10,000 species of bacterium in a single gram of soil, yet only 3,000 have so far been identified and named by microbiologists. Conservative estimates put the number of different species on Earth at 14 million; no one knows for sure and some have claimed that there are at least 30 million. Of these, only a few per cent -- 2 million at most -- have been studied, identified, named. Indeed, almost all biological research has been based on a few hundred different life forms at most. The smallest independently living organisms are no more than 0.2 micrometres -- one-fifth of a millionth of a metre -- in diameter; the largest living animal, the blue whale, can grow to more than 30 metres and may weigh 200 tonnes -- heavier than any known extinct dinosaur. Bacteria live for 20 minutes or so before dividing into two; near where I live in Yorkshire is an elderly oak tree which was noted in William the Conqueror's Domesday Book nearly a thousand years ago. And some Californian redwoods far outstrip whales and oak trees, reaching nearly 100 metres in height and at least 2,500 years of age.
What a world to be living in, to marvel at, to enjoy in all its multifarious variety. `O brave new world, that has such creatures in't,' to paraphrase the old wizard Prospero's daughter Miranda in The Tempest. And her voice echoes the feelings of poets, painters and writers throughout recorded history.
But to study, to interpret, to understand, to explain and to predict? These are the tasks of myth-makers, magicians and, above all today, of scientists, of biologists. I am of this last category. We seek not to lose the visions provided by writers and artists, but to add to them new visions which come from the ways of knowing that biology, the science of life, opens up. These ways can show beauty also below the surface of things: in the scanning electron microscope's view of the eye of a bluebottle as much as in the flowering of a camellia; in the biochemical mechanisms that generate usable energy in the minuscule sausage-shaped mitochondria that inhabit each of our body cells, as much as in the flowing muscles of the athlete who exploits these mechanisms.
How are we to understand these multitudes of organisms, these orders-of-magnitude differences in space and time encompassed by the common definition of living forms? Humans are like, yet unlike, any other species on Earth. We have had to learn to adapt to, domesticate, subordinate, protect ourselves from or exist harmoniously with a goodly proportion of the other creatures with which we share our planet. And in doing so, to make theories about them. Every society that anthropologists have studied has developed its own theories and legends to account for life and our place within it, to interpret the great transitions that characterize our existence; the creation of new life at birth and its termination at death. In most societies' creation myths, a deity imposes order upon the confused mass of struggling life. Although our own society is no exception, we now phrase things differently, claiming to have transcended myth and replaced it with secure knowledge. For the last three hundred years, Western societies have built on and transcended their own creation myths by means of scientia, the organized investigation of the universe, made possible within the rules and by the experimental methods of natural science, and with the aid of powerful instruments designed to extend the human senses of touch, smell, taste, sight and sound.
THE POWER OF BIOLOGY
The power of Western science as it has developed over the past three centuries derived in the first instance from its capacity to explain, and later from its power to control, aspects of the non-living world in the province of physics and chemistry. Only subsequently were the methods and theories that had been shaped by the success of these older sciences turned towards the study of living processes. The several sciences that today comprise biology have been barely six generations in the making, and have been transformed beyond measure even within my own lifetime. Despite our ignorance of the overwhelming majority of life forms which exist on Earth today (indeed, most biochemical and genetic generalizations are still derived from just three organisms: the rat, the fruit fly and the common gut bug Escherichia coli), and our inability to do more than offer informed speculations about the processes that have given rise to them over the past 4 billion years, we biologists are beginning to lay claims to universal knowledge, of what life is, how it emerged and how it works. In all life forms, in all living processes, we argue, certain general principles hold; certain mechanisms, certain forms of chemistry, exist in common. Some have even gone further, arguing that what they deduce to be true of life on Earth is but a special case of a phenomenon so universal that its rules must apply to all living forms anywhere in the universe.
The successes of science have been based not so much on observation and contemplation, but on active intervention in the phenomena for which explanations were being sought. When addressed to purely chemical and physical processes, such interventions seldom present significant problems of ethics, of challenges to the very right of the researcher to intervene. But there is no doubt that intervention in living processes confronts us all -- not just researchers, but also the society which has come to depend upon the results of their research -- with moral dilemmas. We cannot escape the fact that interventionist biology, and above all physiology, is a science built on violence, on `murdering to dissect', and that hitherto there has been no alternative means of discovering the intimate molecular and cellular events that, at least on one level of description, constitute life itself. The reductive philosophy that has proved so seductive to biologists yet so hazardous in its consequences seems an almost inevitable product of this interventionist and necessarily violent methodology.
More than most sciences today, biology impinges directly on how we live. Like chemistry and physics, its technologies transform our personal, social and natural environments via pharmacology, genetic engineering and agribusiness. Biology also makes claims as to who we are, about the forces that shape the deepest aspects of our personalities, and even about our purposes here on Earth. The claims of the science have become so strong as to seem no longer a matter for debate: they are now the natural way to view the living world. Indeed, today we even use the name given to the science, biology, to replace its field of study -- life itself and the processes which sustain it; the science has usurped its subject. So `biological' becomes the antonym not for `sociological' but for `social'.
FREEDOM AND DETERMINISM
Hence the epigraphs to this chapter. These two diametrically opposed views on the nature of human nature, of the relationship between our thoughts and actions on the one hand and our chemical constitution -- DNA's way of making more DNA -- on the other, represent the extremes between which I have tried to steer this book. The first, a windily rhetorical paean to the dignity of universalistic man (I suspect the gendering is not irrelevant) written just after the liberation of France from Nazi occupation, is from the existentialist philosopher Jean-Paul Sartre. The second, with all the brash style of a cheeky adolescent cocking a snook at everything his elders hold dear, is from Richard Dawkins, the St John the Baptist of sociobiology, and was drafted in the comfort of an Oxford college in the mid-1970s. Each has been fashionable in its time, but there is no doubt which better reflects the spirit of the past two decades.
Each of course is more an exercise in political sloganeering than a sustainable philosophical position. How does Sartre's freedom deal with the inexorability of human decline, the ravages of cancer, the destructive onset of Alzheimer's disease? And how does Dawkins' gene's-eye view of the world account for the horrors of the Nazi concentration camps or the heroes and heroines of the French resistance? Of course, neither viewpoint sprang fully formed from its author's pen; each had a long lineage in religious, philosophical and scientific debate. And I am not so naive as to assume that my argument with regard to both positions will be the last word on the subject. However, it is worth stating my thesis right from the beginning. Humans are not empty organisms, free spirits constrained only by the limits of our imaginations or, more prosaically, by the social and economic determinants within which we live, think and act. Nor are we reducible to `nothing but' machines for the replication of our DNA. We are, rather, the products of the constant dialectic between `the biological' and `the social' through which humans have evolved, history has been made and we as individuals have developed (and note already in this sentence my elision of the science of biology with the subject of its study, human life).
To argue otherwise is fundamentally to misunderstand the nature of living processes which it is the purpose of biological science to identify and interpret. Furthermore, our difficulty in thinking our way beyond such antitheses, often expressed as a false dichotomy between nature and nurture, itself derives from the social, philosophical and religious framework within which modern science has developed since its origins, contemporaneous with the birth of capitalism, in seventeenth-century north-western Europe. But it is as a biologist by training and trade, rather than as a philosopher or historian of science, that I shall argue that the naive -- even vulgar -- reductionism and determinism which often masquerade as representative of how biology perceives the world is mistaken. It is not that we are the isolated, autonomous units of Sartre's imagination; rather, our freedom is inherent in the living processes that constitute us.
The science we do, the theories we prefer, and the technologies we use and create as part of that science can never be divorced from the social context in which they are created, the purposes of those who fund the science, and the world-views within which we seek and find appropriate answers to the great what, why and how questions that frame our understanding of life's purposes. So, certainly, with modern biology, whose multifarious answers to these questions are imbued with social and political significance. The prevailing fashion for giving genetic explanations to account for many if not all aspects of the human social condition -- from the social inequalities of race, gender and class to individual propensities such as sexual orientation, use of drugs or alcohol, or the failures of the homeless or psychologically distressed to survive effectively in modern society -- is the ideology of biological determinism, typified by the extrapolations of evolutionary theory that comprise much of what has become known as sociobiology. (This is the assemblage of theories and assertions about humans and society which claims that it is evolutionary theory rather than sociology, economics or psychology that can best explain how and why we live as we do.) It is not possible to write a book such as this without referring to these claims and their politics, and I shall certainly question their legitimacy. But this is not my main task. It is rather to offer an alternative vision of living systems, a vision which recognizes the power and role of genes without subscribing to genetic determinism, and which recaptures an understanding of living organisms and their trajectories through time and space as lying at the centre of biology. It is these trajectories that I call lifelines. Far from being determined, or needing to invoke some non-material concept of free will to help us escape the determinist trap, it is in the nature of living systems to be radically indeterminate, to continually construct their -- our -- own futures, albeit in circumstances not of our own choosing.
THE COMPLEXITY OF BIOLOGY
Science is assumed to be about both explaining and predicting. There is commonly supposed to be a hierarchy of the sciences, from physics through chemistry, biology and the human sciences. In this scheme physics is seen as the most fundamental of the sciences. There are several reasons for this. Partly, physics is believed to deal with the most general principles by which nature is organized. It both provides explanations of natural phenomena and predicts outcomes, from the falling of an apple to an eclipse of the Moon. Furthermore, the `laws of physics apply to biology, but if there are `laws' of biology they do not apply to non-living systems. Physics is thus a `hard' science, whose principles can be expressed mathematically, and so it is supposed to be the model to which all other sciences should aspire. By contrast, the social and human sciences are seen as the `softest' because they are the least capable of precise mathematical expression, and because they do not neatly fit the definition of what `science' is about set out in the first sentence of this paragraph. Indeed, it can be argued that the `predictive' tag is put there precisely to privilege simple sciences like physics and chemistry, which were the first of the modern sciences to develop, against those, like the social sciences and many areas of biology, which (as will become clear in what follows) are multiply determined, and do not even set out to predict (Figure 1.1).
For many, scientists and lay public alike, the hierarchical convention none the less seems obvious, natural. Early in the twentieth century there was a determined effort by physicists and philosophers to insist on a unity of the sciences in which, in due course, physics would triumph. Orthodox philosophy is still mainly a philosophy of physics premised on the reductionist view that the task of science is ultimately to collapse biology into chemistry and chemistry into physics, deriving a limited number of universal laws which will explain the entire universe. The physicist Steven Weinberg has argued this reductionist case with elegance and passion in his book Dreams of a Final Theory. He takes care to point out that many biologists will not concede such reductionism, recounting his own disagreements with the evolutionary biologist Ernst Mayr, But Weinberg's view remains popular. `There is only one science, physics: everything else is social work' as molecular biologist James Watson has put it with characteristic robustness. And many biologists, whose own experimental programmes should perhaps help them know better, accede willingly.
Yet there is nothing inevitable about such a hierarchical view. It is a historically determined convention which reflects the particular traditions of the ways in which Western science has developed from its origins in the seventeenth century. Physics deals with relatively simple, reproducible phenomena which can be measured with exquisite precision, and finds it hard to deal with complexity. Biologists' questions about the world are not easily answerable in the reduced, mathematicizing language of physics, and they are said to suffer from a sense of inferiority, of `physics envy' (which may perhaps be why these days many molecular biologists try to behave as if they are physicists!). But we should not be afraid to cut ourselves loose from the reductionist claims that there is only one epistemology, one way to study and understand the world; one science, whose name is physics. Not everything is capable of being captured in a mathematical formula. Some properties of living systems are not quantifiable, and attempts to put numbers on them produce only mystification (as, for instance, with attempts to score intelligence or aggression, or calculate how many bits of information -- memories -- the brain can store). Biology needs to be able to declare its independence from spurious attempts to mathematicize it. To see why, here's a fable:
FIVE WAYS OF LOOKING AT FROGS
Once upon a time, five biologists were having a picnic by a pool, when they noticed a frog, which had been sitting on the edge, suddenly jump into the water (Figure 1.2.). A discussion began between them: why did the frog jump?
Says the first biologist, a physiologist, `It's really quite straightforward. The frog jumps because the muscles in its legs contract; in turn these contract because of impulses in the motor nerves arriving at the muscles from the frog's brain; these impulses originate in the brain because previous impulses, arriving at the brain from the frog's retina, have signalled the presence of a predatory snake.'
This is a simple `within-level' causal chain: first the retinal image of the snake; then the signals to the brain; then the impulses down the nerves from the brain; then the muscle contraction -- one event following the other, all in a few thousandths of a second (Figure 1.3). Working out the details of such causal sequences is the task of physiology.
`But this is a very limited explanation,' says the second, who is an ethologist, and studies animal behaviour. `The physiologist has missed the point, and has told us how the frog jumped but not why it jumped. The reason why is because it sees the snake and in order to avoid it. The contraction of the frog's muscles is but one aspect of a complex process, and must be understood in terms of the goals of that process -- in this case, to escape being eaten. The ultimate goal of avoiding the snake is essential to understanding the action.'
Such goal-directed explanations, which are known as teleonomic, have given more trouble to philosophers than almost anything else in biology; they are sometimes regarded as bad form, yet they make more everyday sense than most other explanations. They insist that an organism, a piece of behaviour or of physiology, can be understood only within an environmental context which includes both its physical surroundings and other living, socially interacting neighbours. (Indeed, when the organism is a member of that very peculiar species, Homo sapiens, then further complexities, those of personal and collective history, come strongly into play.) This type of explanation is a `top-down' one (it is sometimes called a holistic explanation, a dangerously ambiguous word, which I shall avoid). But notice that, unlike the physiologist's explanation, it is not causal in the sense of describing a temporal chain of events in which first one thing, the nerve firing, and then another, the muscle contraction, happen one after the other in time. The jump inevitably precedes achieving the goal towards which it is directed. Thus when animal behaviourists -- ethologists -- talk of causes, they do so quite differently from physiologists.
`Neither the physiologist's nor the ethologist's explanations are adequate,' says the third biologist, who studies development. `For the developmentalist, the only reason that the frog can jump at all is because during its development, from single fertilized egg through tadpole to mature animal, its nerves, brain and muscles have become "wired up" in such a way that such sequences of activity are inevitable -- or at least, the most probable given any set of starting conditions.'
The process of wiring is an aspect of ontogeny, the development of the organism from conception to adulthood, and is addressed by genetics and developmental biology. Unlike the first two explanations, the ontogenetic approach introduces a historical element into the account: the individual history of the frog becomes the key to understanding its present behaviour. Ontogeny is often seen as a dialogue -- even a dichotomy -- between nature (genetics) and nurture (environment). There have even been attempts to mathematicize this split, and to ask how much is contributed by genes and how much by environment. As will become clear in later chapters, this is a spurious dichotomy and I shall endeavour to transcend it.
`None of these three explanations is very satisfactory,' counters the fourth biologist, an evolutionist. `The frog jumps because during its evolutionary history it was adaptive for its ancestors to do so at the sight of a snake; those ancestors that failed so to do were eaten, and hence their progeny failed to be selected.'
This type of explanation presents problems of defining just what is meant by terms like `adaptive' and `selected', problems which have been raised most sharply in the polemical debate over sociobiology, and which I shall examine rather critically in later chapters. One might contrast the developmentalist and the evolutionist by regarding the first, like the physiologist, as asking how and the second, like the ethologist, as asking why-type questions. The evolutionary explanation combines the historical -- though now with regard to an entire species rather than one individual -- with the goal-directed. Perhaps because of this, some sociobiologists argue that it is the fundamentally causal question and dismiss other causal claims as merely `functional'.
The fifth biologist, a molecular biologist, smiles sweetly. `You have all missed the point. The frog jumps because of the biochemical properties of its muscles. The muscles are composed largely of two interdigitated filamentous proteins, called actin and myosin, and they contract because the protein filaments slide past one another. This behaviour of the actin and myosin is dependent on the amino acid composition of the two proteins, and hence on chemical properties, and hence on physical properties.' This is a reductionist programme, and is the way in which biochemists seek to describe living phenomena.
But note again that this is not a causal chain in the sense in which the physiologist uses the phrase. It is not a question of first one thing happening (the actin and myosin sliding across each other), then another (the contraction). If the word `cause' is used at all here, it must mean something quite different from how it is used in physiology. The confusion about the several ways in which `cause' is used has bedevilled scientific thinking since the days of Aristotle. Perhaps we would see things more clearly if we restricted our use of the word to clear temporal sequences in which first one and then another event occurs. Each of these events -- the image on the frog's retina, the processing in the brain, the transmission down a motor nerve and the muscle contraction itself -- can be translated into the language of biochemistry. And of course it is possible to describe this biochemical sequence in temporal terms too, in which one set of biochemical processes (the molecular events in the nerve), produces another (the sliding actin and myosin filaments). At issue, then, is the relationship between the two temporal sequences, that of the physiologist and that of the biochemist. In later chapters I shall explain why I use the term `translation, to describe how the description of the phenomenon of muscle contraction in the language of (at the level of) physiology may be replaced by a series of presumed identity statements in the languages of biochemistry, chemistry, and so on.
IT ALL DEPENDS ...
Biologists need all these five types of explanation -- and probably others besides. There is no one correct type; it all depends on our purposes in asking the question about the jumping frog in the first case. Indeed, it turns out that `it all depends' is a major feature both of living processes and of biologists' attempts to explain them. The reason for asking the question will determine the most useful type of answer. It is in the nature of biological thinking that all types of answer are -- or ought to be -- part of how we try to understand the world. Biology requires this sort of epistemological pluralism -- to dignify our fuzzy way of thinking with a more formal philosophical imprimatur. To focus on any subset of explanations is to provide only a partial story; to try to understand completely even the simplest of living processes requires that we work with all five types simultaneously. None the less, the way in which the sciences of biology have developed means that excessive deference is paid to the more reductionist type of explanation, as if it were in some way more fundamental, more `really' scientific, or as if at some future time it will even make the others redundant. Biochemists and molecular biologists, and indeed the fund-givers who support our research -- government, industry, charities -- are trained to think and argue in this way. It has become not second, but first nature for us.
BIOLOGY IN TIME The concept of time, and the idea of a direction of `time's arrow', are central to biology. For many if not most aspects of the phenomena which physics studies, `time's arrow' is reversible: processes can be driven in both forward and backward directions. The properties of matter and the `laws' defining interactions are generally assumed to be uniform in space and time, even though our own human understanding of those laws is itself historically determined. Time, history, becomes relevant to physics and chemistry only in the context of cosmology. For much of biology such simplicity does not apply. Although the properties of living systems and processes are of course entirely in accord with the principles of physics and chemistry, a full understanding of them lies beyond the regularities that characterize those sciences' objects of study. Living processes are complex, often irreproducible because historically contingent, and are hence also practically irreversible. The arrow of time runs in one direction only: the direction studied by the developmental and evolutionary biologists in the frog fable.
For biologists, humans are not the product of special creation by an all-wise and all-powerful deity, but the more or less accidental product of evolutionary forces working over almost unimaginable aeons of time. Evolutionary biology has to write a history of life that has persisted for some four billion years. Most of us (scientists as well, in our day-to-day lives away from lab and computer) find it hard to think beyond a few generations: our own, our parents' and our children's lifetimes, a century or so, is about all we can manage. Yet the time-scale about which we have to think is surpassed only by that of the cosmologists with their universe of times and distances measured in billions of years and millions of light years -- and light travels, we should not forget, at some 300,000 kilometres a second.
Evolution over time is a central biological theme; the past is the key to the present. Life as we now know it results from the combinations of chance and necessity that comprise evolutionary processes. Necessity, given by the physical and chemical properties of the universe; and chance, contingency, by the radical indeterminacy of living processes which it will be one of the purposes of this book to explore. That is, the indeterminacy is not merely a matter of ignorance, or lack of adequate technology; it is inherent in the nature of life itself. Indeed, the great population geneticist Theodosius Dobzhansky asserted that `nothing in biology makes sense except in the light of evolution'. However, I wish to go several steps further. Nothing in biology makes Sense except in the light of history, by which I mean simultaneously the history of life on Earth -- evolution, Dobzhansky's concern -- and the history of the individual organism -- its development, from conception to death. But I have a third step to take as well. We cannot understand why biologists at the end of the twentieth century think as they -- we -- do about the nature of life and living processes without understanding the history of our own subject, biology. For us too, the past is the key to the present.