For some purposes this does not greatly matter, but when we are talking about altruism it is obviously crucial. If it is species that are competing in what Darwin called the struggle for existence, the individual seems best regarded as a pawn in the game, to be sacrified when the greater interest of the species as a whole requires it.
To put it in a slightly more respectable way, a group, such as a species or a population within a species, whose individual members are prepared to sacrifice themselves for the welfare of the group, maybe less likely to go extinct than a rival group whose individual members place their own selfish interests first. Therefore the world becomes populated mainly by groups consisting of self-sacrificing individuals.
This is the theory of'group selection', long assumed to be true by biologists not familiar with the details of evolutionary theory, brought out into the open in a famous book by V.
The orthodox alternative is normally called 'individual selection', although I per- sonally prefer to speak of gene selection. The quick answer of the 'individual selectionist' to the argument just put might go something like this. Even in the group of altruists, there will almost certainly be a dissenting minority who refuse to make any sacrifice.
Each of these children will tend to inherit his selfish traits. After several generations of diis natural selection, the 'altruistic group' will be over-run by selfish individuals, and will be indistinguishable from the selfish group.
Even if we grant the improbable chance existence initially of pure altruistic groups without any rebels, it is very difficult to see what is to stop selfish individuals migrating in from neighbouring selfish groups, and, by inter-marriage, contaminating the purity of the altruistic groups. The individual-selectionist would admit that groups do indeed die out, and that whether or not a group goes extinct may be influenced by the behaviour of the individuals in that group. He might even admit that if only the individuals in a group had the gift of foresight they could see that in the long run their own best interests lay in restraining their selfish greed, to prevent the destruction of the whole group.
How many times must this have been said in recent years to the working people of Britain? But group extinction is a slow process compared with the rapid cut and thrust of individual competition. Even while the group is going slowly and inexorably downhill, selfish individuals prosper in the short term at the expense of altruists. The citizens of Britain may or may not be blessed with foresight, but evolution is blind to the future.
Although the group-selection theory now commands little sup- port within the ranks of those professional biologists who understand evolution, it does have great intuitive appeal. Successive generations of zoology students are surprised, when they come up from school, to find that it is not the orthodox point of view.
For this they are hardly to be blamed, for in the NuffieldBiology Teachers' Guide, written for advanced level biology schooteachers in Britain, we find the follow- ing: 'In higher animals, behaviour may take the form of individual suicide to ensure the survival of the species. In this respect he is in Nobel Prize-winning company. Konrad Lorenz, in On Aggression, speaks of the 'species preserving' functions of aggressive behaviour, one of these functions being to make sure that only the fittest individuals are allowed to breed.
This is a gem of a circular argument, but the point I am making here is that the group selection idea is so deeply ingrained that Lorenz, like the author of the Nuffield Guide, evidently did not realize that his statements contravened orthodox Darwinian theory. The 'expert' on the programme observed that the vast majority of baby spiders end up as prey for other species, and she then went on to say: 'Perhaps this is the real purpose of their existence, as only a few need to survive in order for the species to be preserved'!
Robert Ardrey, in The Social Contract, used the group-selection theory to account for the whole of social order in general. He clearly sees man as a species that has strayed from the path of animal righteousness. Ardrey at least did his homework.
His decision to disagree with orthodox theory was a conscious one, and for this he deserves credit. Perhaps one reason for the great appeal of the group-selection theory is that it is thoroughly in tune with the moral and political ideals that most of us share.
We may frequently behave selfishly as individuals, but in our more idealistic moments we honour and admire those who put the welfare of others first. We get a bit muddled over how widely we want to interpret the word 'others', though. Often altruism within a group goes with selfishness between groups. This is a basis of trade unionism. At another level the nation is a major beneficiary of our altruistic self-sacrifice, and young men are expected to die as individuals for the greater glory of their country as a whole.
Moreover, they are encouraged to kill other individuals about whom nothing is known except that they belong to a different nation. Curiously, peace-time appeals for individuals to make some small sacrifice in the rate at which they increase their standard of living seem to be less effective than war-time appeals for individuals to lay down their lives. Recently there has been a reaction against racialism and patriot- ism, and a tendency to substitute the whole human species as the object of our fellow feeling.
This humanist broadening of the target of our altruism has an interesting corollary, which again seems to buttress the 'good of the species' idea in evolution. The politically liberal, who are normally the most convinced spokesmen of the species ethic, now often have the greatest scorn for those who have gone a little further in widening their altruism, so that it includes other species.
If I say that I am more interested in preventing the slaughter of large whales than I am in improving housing conditions for people, I am likely to shock some of my friends. The feeling that members of one's own species deserve special moral consideration as compared with members of other species is old and deep. Killing people outside war is the most seriously- regarded crime ordinarily committed.
The only thing more strongly forbidden by our culture is eating people even if they are already dead. We enjoy eating members of other species, however. Many of us shrink from judicial execution of even the most horrible human criminals, while we cheerfully countenance the shooting without trial of fairly mild animal pests. Indeed we kill members of other harmless species as a means of recreation and amusement. A human foetus, with no more human feeling than an amoeba, enjoys a reverence and legal protection far in excess of those granted to an adult chimpanzee.
Yet the chimp feels and thinks and—according to recent experimental evidence—may even be capable of learning a form of human language. The foetus belongs to our own species, and is instantly accorded special privileges and rights because of it.
Whether the ethic of'speciesism', to use Richard Ryder's term, can be put on a logical footing any more sound than that of'racism', I do not know. What I do know is that it has no proper basis in evolutionary biology. The muddle in human ethics over the level at which altruism is desirable—family, nation, race, species, or all living things—is mirrored by a parallel muddle in biology over the level at which altruism is to be expected according to the theory of evolution.
Even the group-selectionist would not be surprised to find members of rival groups being nasty to each other: in this way, like trade unionists or soldiers, they are favouring their own group in the struggle for limited resources. But then it is worth asking how the group- selectionist decides which level is the important one.
If selection goes on between groups within a species, and between species, why should it not also go on between larger groupings? Species are grouped together into genera, genera into orders, and orders into classes.
Lions and antelopes are both members of the class Mam- malia, as are we. Should we then not expect lions to refrain from killing antelopes, 'for the good of the mammals'? Surely they should hunt birds or reptiles instead, in order to prevent the extinction of the class.
But then, what of the need to perpetuate the whole phylum of vertebrates? Ardrey goes so far as to say that group selection is the only possible explanation for behaviour such as 'storting' in Thomson's gazelles.
This vigorous and conspicuous leaping in front of a predator is analogous to bird alarm calls, in that it seems to warn companions of danger while apparently calling the predator's attention to the stotter himself. We have a responsibility to explain storting Tommies and all similar phenomena, and this is something I am going to face in later chapters. Before that I must argue for my belief that the best way to look at evolution is in terms of selection occurring at the lowest level of all.
In this belief I am heavily influenced by G. Williams's great book Adaptation and Natural Selection. The central idea I shall make use of was foreshadowed by A. Weismann in pre-gene days at the turn of the century—his doctrine of the 'continuity of the germ-plasm'. I shall argue that the fundamental unit of selection, and therefore of self-interest, is not the species, nor the group, nor even, strictly, the individual. It is the gene, the unit of heredity. I hope when they see in what sense I mean it they will agree that it is, in substance, orthodox, even if it is expressed in an unfamiliar way.
The argument takes time to develop, and we must begin at the beginning, with the very origin of life itself. It is difficult enough explaining how even a simple universe began.
I take it as agreed that it would be even harder to explain the sudden springing up, fully armed, of complex order—life, or a being capable of creating life. Darwin's theory of evolution by natural selection is satisfying because it shows us a way in which simplicity could change into complexity, how unordered atoms could group themselves into ever more complex patterns until they ended up manufacturing people.
Darwin provides a solution, the only feasible one so far suggested, to the deep problem of our existence. I will try to explain the great theory in a more general way than is customary, beginning with the time before evolution itself began. Darwin's 'survival of the fittest' is really a special case of a more general law of survival of the stable. The universe is populated by stable things.
A stable thing is a collection of atoms that is permanent enough or common enough to deserve a name. It may be a unique collection of atoms, such as the Matterhorn, that lasts long enough to be worth naming. Or it may be a class of entities, such as rain drops, that come into existence at a sufficiently high rate to deserve a collective name, even if any one of them is short-lived.
The things that we see around us, and which we think of as needing explana- tion—rocks, galaxies, ocean waves—are all, to a greater or lesser extent, stable patterns of atoms. Soap bubbles tend to be spherical because this is a stable configuration for thin films filled with gas.
In a spacecraft, water is also stable in spherical globules, but on earth, where there is gravity, the stable surface for standing water is flat and horizontal. Salt crystals tend to be cubes because this is a stable way of packing sodium and chloride ions together.
In the sun the simplest atoms of all, hydrogen atoms, are fusing to form helium atoms, because in the conditions that prevail there the helium configuration is more stable. This is originally where the elements on our world came from. Sometimes when atoms meet they link up together in chemical reaction to form molecules, which may be more or less stable. Such molecules can be very large. A crystal such as a diamond can be regarded as a single molecule, a proverbially stable one in this case, but also a very simple one since its internal atomic structure is endlessly repeated.
In modern living organisms there are other large molecules which are highly complex, and their complexity shows itself on several levels. The haemoglobin of our blood is a typical protein molecule. It is built up from chains of smaller molecules, amino acids, each containing a few dozen atoms arranged in a precise pattern. In the haemoglobin molecule there are amino acid molecules. These are arranged in four chains, which twist around each other to form a globular three-dimensional structure of bewildering complexity.
A model of a haemoglobin molecule looks rather like a dense thornbush. But unlike a real thornbush it is not a haphazard approximate pattern but a definite invariant structure, identically repeated, with not a twig nor a twist out of place, over six thousand million million million times in an average human body.
The precise thornbush shape of a protein molecule such as haemoglobin is stable in the sense that two chains consisting of the same sequences of amino acids will tend, like two springs, to come to rest in exactly the same three-dimensional coiled pattern. Haemoglobin thornbushes are springing into their 'preferred' shape in your body at a rate of about four hundred million million per second, and others are being destroyed at the same rate. Haemoglobin is a modern molecule, used to illustrate the principle that atoms tend to fall into stable patterns.
The point that is relevant here is that, before the coming of life on earth, some rudimentary evolution of molecules could have occurred by ordinary processes of physics and chemistry. There is no need to think of design or purpose or directedness.
If a group of atoms in the presence of energy falls into a stable pattern it will tend to stay that way. The earliest form of natural selection was simply a selection of stable forms and a rejection of unstable ones. There is no mystery about this.
It had to happen by definition. It is no good taking the right number of atoms and shaking them together with some external energy till they happen to fall into the right pattern, and out drops Adam!
You may make a molecule consisting of a few dozen atoms like that, but a man consists of over a thousand million million million million atoms. To try to make a man, you would have to work at your biochemical cocktail-shaker for a period so long that the entire age of the universe would seem like an eye-blink, and even then you would not succeed.
This is where Darwin's theory, in its most general form, comes to the rescue. Darwin's theory takes over from where the story of the slow building up of molecules leaves off. The account of the origin of life that I shall give is necessarily speculative; by definition, nobody was around to see what happened. There are a number of rival theories, but they all have certain features in common.
The simplified account I shall give is probably not too far from the truth. Chemists have tried to imitate the chemical conditions of the young earth.
They have put these simple sub- stances in a flask and supplied a source of energy such as ultraviolet light or electric sparks—artificial simulation of primordial lightning.
After a few weeks of this, something interesting is usually found inside the flask: a weak brown soup containing a large number of molecules more complex than the ones originally put in. In particu- lar, amino acids have been found—the building blocks of proteins, one of the two great classes of biological molecules. Before these experiments were done, naturally-occurring amino acids would have been thought of as diagnostic of the presence of life.
If they had been detected on, say Mars, life on that planet would have seemed a near certainty. Now, however, their existence need imply only the presence of a few simple gases in the atmosphere and some volcanoes, sunlight, or thundery weather. More recently, laboratory simulations of the chemical conditions of earth before the coming of life have yielded organic substances called purines and pyrimidines. These are building blocks of the genetic molecule, DNA itself.
The organic sub- stances became locally concentrated, perhaps in drying scum round the shores, or in tiny suspended droplets. Under the further influence of energy such as ultraviolet light from the sun, they combined into larger molecules. Nowadays large organic molecules would not last long enough to be noticed: they would be quickly absorbed and broken down by bacteria or other living creatures. But bacteria and the rest of us are late-comers, and in those days large organic molecules could drift unmolested through the thickening broth.
At some point a particularly remarkable molecule was formed by accident. We will call it the Replicator. It may not necessarily have been the biggest or the most complex molecule around, but it had the extraordinary property of being able to create copies of itself.
This may seem a very unlikely sort of accident to happen. So it was. It was exceedingly improbable. In the lifetime of a man, things that are that improbable can be treated for practical purposes as impossible. That is why you will never win a big prize on the football pools. But in our human estimates of what is probable and what is not, we are not used to dealing in hundreds of millions of years.
If you filled in pools coupons every week for a hundred million years you would very likely win several jackpots. Actually a molecule that makes copies of itself is not as difficult to imagine as it seems at first, and it only had to arise once. Think of the replicator as a mould or template. Imagine it as a large molecule consisting of a complex chain of various sorts of building block molecules.
The small building blocks were abundantly available in the soup surrounding the replicator. Now suppose that each building block has an affinity for its own kind. Then whenever a building block from out in the soup lands up next to a part of the replicator for which it has an affinity, it will tend to stick there.
The building blocks that attach themselves in this way will automatically be arranged in a sequence that mimics that of the replicator itself. It is easy then to think of them joining up to form a stable chain just as in the formation of the original replicator.
This process could continue as a progress- ive stacking up, layer upon layer. This is how crystals are formed. On the other hand, the two chains might split apart, in which case we have two replicators, each of which can go on to make further copies.
A more complex possibility is that each building block has affinity not for its own kind, but reciprocally for one particular other kind. For our purposes it does not matter whether the original replication process was positive-negative or positive-positive, though it is worth remarking that the modern equivalents of the first replicator, the DNA molecules, use positive- negative replication.
What does matter is that suddenly a new kind of 'stability' came into the world. Previously it is probable that no particular kind of complex molecule was very abundant in the soup, because each was dependent on building blocks happening to fall by luck into a particular stable configuration. As soon as the replicator was born it must have spread its copies rapidly throughout the seas, until the smaller building block molecules became a scarce resource, and other larger molecules were formed more and more rarely.
So we seem to arrive at a large population of identical replicas. But now we must mention an important property of any copying process: it is not perfect. Mistakes will happen.
I hope there are no misprints in this book, but if you look carefully you may find one or two. They will probably not seriously distort the meaning of the sentences, because they will be 'first generation' errors. But imagine the days before printing, when books such as the Gospels were copied by hand.
All scribes, however careful, are bound to make a few errors, and some are not above a little wilful 'improvement'. If they all copied from a single master original, meaning would not be greatly perverted. But let copies be made from other copies, which in their turn were made from other copies, and errors will start to become cumulative and serious. We tend to regard erratic copying as a bad thing, and in the case of human documents it is hard to think of examples where errors can be described as improvements.
I suppose the scholars of the Septuagint could at least be said to have started something big when they mistranslated the Hebrew word for 'young woman' into the Greek word for 'virgin', coming up with the prophecy: 'Behold a virgin shall conceive and bear a son.
We do not know how accurately the original replicator molecules made their copies. Probably the original replicators were far more erratic, but in any case we may be sure that mistakes were made, and these mistakes were cumulative.
As mis-copyings were made and propagated, the primeval soup became filled by a population not of identical replicas, but of several varieties of replicating molecules, all 'descended' from the same ancestor. Would some varieties have been more numerous than others? Almost certainly yes. Some varieties would have been inherently more stable than others.
Certain molecules, once formed, would be less likely than others to break up again. These types would become relatively numerous in the soup, not only as a direct logical consequence of their 'longevity', but also because they would have a long time available for making copies of themselves. Replicators of high longevity would therefore tend to become more numerous and, other things being equal, there would have been an 'evolutionary trend' towards greater longevity in the population of molecules.
But other things were probably not equal, and another property of a replicator variety that must have had even more importance in spreading it through the population was speed of replication or 'fecundity'. If replicator molecules of type A make copies of them- selves on average once a week while those of type B make copies of themselves once an hour, it is not difficult to see that pretty soon type A molecules are going to be far outnumbered, even if they 'live' much longer than B molecules.
There would therefore probably have been an 'evolutionary trend' towards higher 'fecundity' of molecules in the soup.
A third characteristic of replicator molecules which would have been positively selected is accuracy of replication. If molecules of type X and type Flast the same length of time and replicate at the same rate, but X makes a mistake on average every tenth replication while Y makes a mistake only every hundredth replication, Y will obviously become more numerous. If you already know something about evolution, you may find something slightly paradoxical about the last point.
Can we reconcile the idea that copying errors are an essential prerequisite for evolu- tion to occur, with the statement that natural selection favours high copying-fidelity? Evolution is something that happens, willy-nilly, in spite of all the efforts of the replicators and nowadays of the genes to prevent it happening.
Jacques Monod made this point very well in his Herbert Spencer lecture, after wryly remarking: 'Another curious aspect of the theory of evolution is that everybody thinks he understands it! This is essentially what a biologist means by evolution when he is speaking of living creatures, and the mechanism is the same—natural selection.
Should we then call the original replicator molecules 'living'? Who cares? I might say to you 'Darwin was the greatest man who has ever lived', and you might say 'No, Newton was', but I hope we would not prolong the argument. The point is that no conclusion of substance would be affected whichever way our argument was resolved.
The facts of the lives and achievements of Newton and Darwin remain totally unchanged whether we label them 'great' or not. Similarly, the story of the replicator molecules probably happened something like the way I am telling it, regardless of whether we choose to call them 'living'.
Human suffering has been caused because too many of us cannot grasp that words are only tools for our use, and that the mere presence in the dictionary of a word like 'living' does not mean it necessarily has to refer to something definite in the real world. Whether we call the early replicators living or not, they were the ancestors of life; they were our founding fathers.
The next important link in the argument, one that Darwin himself laid stress on although he was talking about animals and plants, not molecules is competition. The primeval soup was not capable of supporting an infinite number of replicator molecules. For one thing, the earth's size is finite, but other limiting factors must also have been important. In our picture of the replicator acting as a template or mould, we supposed it to be bathed in a soup rich in the small building block molecules necessary to make copies.
Different varieties or strains of replicator must have competed for them. We have considered the factors that would have increased the numbers of favoured kinds of replicator. We can now see that less-favoured varieties must actually have become less numerous because of competition, and ultimately many of their lines must have gone extinct.
There was a struggle for existence among replicator varieties. They did not know they were struggling, or worry about it; the struggle was conducted without any hard feelings, indeed without feelings of any kind. But they were struggling, in the sense that any mis-copying that resulted in a new higher level of stability, or a new way of reducing the stability of rivals, was automatically preserved and multiplied.
The process of improve- ment was cumulative. Ways of increasing stability and of decreasing rivals' stability became more elaborate and more efficient. Some of them may even have 'discovered' how to break up molecules of rival varieties chemically, and to use the building blocks so released for making their own copies. These proto-carnivores simultaneously obtained food and removed competing rivals. Other replicators perhaps discovered how to protect themselves, either chemically, or by building a physical wall of protein around themselves.
This may have been how the first living cells appeared. Replicators began not merely to exist, but to construct for themselves containers, vehicles for their continued existence. The replicators that survived were the ones that built survival machines for themselves to live in. The first survival machines probably consisted of nothing more than a protec- tive coat. But making a living got steadily harder as new rivals arose with better and more effective survival machines.
Survival machines got bigger and more elaborate, and the process was cumulative and progressive. Was there to be any end to the gradual improvement in the techniques and artifices used by the replicators to ensure their own continuation in the world? There would be plenty of time for improvement. What weird engines of self-preservation would the millennia bring forth? Four thousand million years on, what was to be the fate of the ancient replicators?
They did not die out, for they are past masters of the survival arts. But do not look for them floating loose in the sea; they gave up that cavalier freedom long ago. They are in you and in me; they created us, body and mind; and their preservation is the ultimate rationale for our existence. They have come a long way, those replicators.
Now they go by the name of genes, and we are their survival machines. It embraces all animals, plants, bacteria, and viruses.
The total number of survival machines on earth is very difficult to count and even the total number of species is unknown. Taking just insects alone, the number of living species has been estimated at around three million, and the number of individual insects may be a million million million. Different sorts of survival machine appear very varied on the outside and in their internal organs.
An octopus is nothing like a mouse, and both are quite different from an oak tree. Yet in their fundamental chemistry they are rather uniform, and, in particular, the replicators that they bear, the genes, are basically the same kind of molecule in all of us—from bacteria to elephants.
We are all survival machines for the same kind of replicator—molecules called DNA—but there are many different ways of making a living in the world, and the replicators have built a vast range of machines to exploit them.
A monkey is a machine that preserves genes up trees, a fish is a machine that preserves genes in the water; there is even a small worm that preserves genes in German beer mats. DNA works in mysterious ways. For simplicity I have given the impression that modern genes, made of DNA, are much the same as the first replicators in the primeval soup. It does not matter for the argument, but this may not really be true.
The original replicators may have been a related kind of molecule to DNA, or they may have been totally different. In the latter case we might say that their survival machines must have been seized at a later stage by DNA. If so, the original replicators were utterly destroyed, for no trace of them remains in modern survival machines. Along these lines, A.
Usurper or not, DNA is in undisputed charge today, unless, as I tentatively suggest in Chapter 11, a new seizure of power is now just beginning. A DNA molecule is a long chain of building blocks, small molecules called nucleotides. Just as protein molecules are chains of amino acids, so DNA molecules are chains of nucleotides. A DNA molecule is too small to be seen, but its exact shape has been ingeniously worked out by indirect means.
It consists of a pair of nucleotide chains twisted together in an elegant spiral; the 'double helix'; the 'immortal coil'. The nucleotide building blocks come in only four different kinds, whose names may be shortened to A, T, C, and G. These are the same in all animals and plants.
What differs is the order in which they are strung together. A G building block from a man is identical in every particular to a G building block from a snail. But the sequence of building blocks in a man is not only different from that in a snail.
It is also different—though less so—from the sequence in every other man except in the special case of identical twins. Our DNA lives inside our bodies. It is not concentrated in a particular part of the body, but is distributed among the cells.
There are about a thousand million million cells making up an average human body, and, with some exceptions which we can ignore, every one of those cells contains a complete copy of that body's DNA. It is as though, in every room of a gigantic building, there was a book-case contain- ing the architect's plans for the entire building. The 'book-case' in a cell is called the nucleus.
The architect's plans run to 46 volumes in man—the number is different in other species. The 'volumes' are called chromosomes. They are visible under a microscope as long threads, and the genes are strung out along them in order. It is not easy, indeed it may not even be meaningful, to decide where one gene ends and the next one begins.
Fortunately, as this chapter will show, this does not matter for our purposes. I shall make use of the metaphor of the architect's plans, freely mixing the language of the metaphor with the language of the real thing. This metaphor will take us quite a long way. Immortal coils 23 When it finally breaks down I shall introduce other metaphors. Incidentally, there is of course no 'architect'. The DNA instructions have been assembled by natural selection.
DNA molecules do two important things. Firstly they replicate, that is to say they make copies of themselves. This has gone on non- stop ever since the beginning of life, and the DNA molecules are now very good at it indeed. As an adult, you consist of a thousand million million cells, but when you were first conceived you were just a single cell, endowed with one master copy of the architect's plans.
This cell divided into two, and each of the two cells received its own copy of the plans. Successive divisions took the number of cells up to 4, 8, 16, 32, and so on into the billions.
At every division the DNA plans were faithfully copied, with scarcely any mistakes. It is one thing to speak of the duplication of DNA. But if the DNA is really a set of plans for building a body, how are the plans put into practice? How are they translated into the fabric of the body? This brings me to the second important thing DNA does. It indirectly supervises the manufacture of a different kind of molecule—protein. The haemoglobin which was mentioned in the last chapter is just one example of the enormous range of protein molecules.
The coded message of the DNA, written in the four-letter nucleotide alphabet, is translated in a simple mechanical way into another alphabet. This is the alphabet of amino acids which spells out protein molecules.
Making proteins may seem a far cry from making a body, but it is the first small step in that direction. Proteins not only constitute much of the physical fabric of the body; they also exert sensitive control over all the chemical processes inside the cell, selectively turning them on and off at precise times and in precise places.
Exactly how this eventually leads to the development of a baby is a story which it will take decades, perhaps centuries, for embryologists to work out. But it is a fact that it does. Genes do indirectly control the manufacture of bodies, and the influence is strictly one way: acquired characteristics are not inherited. No matter how much knowledge and wisdom you acquire during your life, not one jot will be passed on to your children by genetic means.
Each new genera- tion starts from scratch. A body is the genes' way of preserving the genes unaltered. Once upon a time, natural selection consisted of die differential survival of replicators floating free in the primeval soup. Now, natural selection favours replicators that are good at building survival machines, genes that are skilled in the art of controlling embryonic development. In diis, the replicators are no more conscious or purposeful dian they ever were.
The same old processes of automatic selection between rival molecules by reason of their longevity, fecundity, and copying-fidelity, still go on as blindly and as inevitably as they did in die far-off days. Genes have no foresight. They do not plan ahead. Genes just are, some genes more so dian odiers, and diat is all there is to it. But die qualities that determine a gene's longevity and fecundity are not so simple as diey were. Not by a long way. In recent years—die last six hundred million or so—die replic- ators have achieved notable triumphs of survival-machine tech- nology such as die muscle, die heart, and die eye evolved several times independendy.
Before diat, diey radically altered funda- mental features of dieir way of life as replicators, which must be understood if we are to proceed widi die argument. The first thing to grasp about a modern replicator is diat it is highly gregarious. A survival machine is a vehicle containing not just one gene but many diousands.
The manufacture of a body is a cooperative venture of such intricacy diat it is almost impossible to disentangle die contribution of one gene from diat of anodier. A given part of die body will be influenced by many genes, and die effect of any one gene depends on interaction with many odiers.
Some genes act as master genes controlling die operation of a cluster of odier genes. Posting Komentar. Mei 24, In this personal and intimate story, she takes you through the pain of her illness and her miraculous recovery, and how she discovered the simple yet powerful way to help the human body heal through proper nourishment.
Goldner makes it easy to understand this essential information on how food can cause and heal disease, teaching it simply and plainly. She created easy to follow steps you can take to achieving bette. Baca selengkapnya. April 23, Along with the two extra chapters, The Extended Selfish Gene includes a new epilogue to The Selfish Gene from the author which highlights the relevance of the gene's eye view to evolutionary biology today.
The million copy international bestseller, critically acclaimed and translated into over 25 languages. This 30th anniversary edition includes a new introduction from the author as well as the original prefaces and foreword, and extracts from early reviews.
As relevant and influential today as when it was first published, The Selfish Gene has become a classic exposition of evolutionary thought. Professor Dawkins articulates a gene's eye view of evolution - a view giving centre stage to these persistent units of information, and in which organisms can be seen as vehicles for their replication. This imaginative, powerful, and stylistically brilliant work not only brought the insights of Neo-Darwinism to a wide audience, but galvanized the biology community, generating much debate and stimulating whole new areas of research.
Richard Dawkins provides excellent examples of his reasoning and interpretation skills in The Selfish Gene. His book is not a work of original research, but instead a careful explanation of evolution, combined with an argument for a particular interpretation of several aspects of evolution. Since Dawkins is building on other researchers' work and writing for a general audience, the central elements of good reasoning are vital to his book: producing a clear argument and presenting a persuasive case; organising an argument and supporting its conclusions.
In doing this, Dawkins also employs the crucial skill of interpretation: understanding what evidence means; clarifying terms; questioning definitions; giving clear definitions on which to build arguments. The strength of his reasoning and interpretative skills played a key part in the widespread acceptance of his argument for a gene-centred interpretation of natural selection and evolution - and in its history as a bestselling classic of science writing.
Since Dawkins popularized the notion of the selfish gene, the question of how these selfish genes work together to construct an organism remained a mystery. Now, standing atop a wealth of new research, Itai Yanai and Martin Lercher—pioneers in the field of systems biology—provide a vision of how genes cooperate and compete in the struggle for life. Using the theory of Prisoner's Dilemma, Prisoners of Reason explores how neoliberalism departs from classic liberalism and how it rests on game theory.
The central aim of this accessible book is to show how the gene's-eye view differs from the traditional organismal account of evolution, trace its historical origins, clarify typical misunderstandings and, by using examples from contemporary experimental work, show why so many evolutionary biologists still consider it an indispensable heuristic.
From Gaia to Selfish Genes is a different kind of anthology. Lively excerpts from the popular writings of leading theorists in the life sciences blend in a seamless presentation of the controversies and bold ideas driving contemporary biological research.
Selections span scales from the biosphere to the cell and DNA, and disciplines from global ecology to behavior and genetics, and also reveals the links between biology and philosophy. They plunge the reader into debates about heredity and environment, competition and cooperation, randomness and determinism, and the meaning of individuality. From Gaia to Selfish Genes conveys the technical and conceptual roots of current scientific theories beginning with the planetary perspective of James Lovelock and Lynn Margulis and concluding with the reductionist views of Richard Dawkins and E.
The contrasting worldviews, coupled with excerpts drawn from critics of each theory, encourage readers to examine their own presuppositions. In addition to the scientists' portrayal of the Gaia hypothesis, symbiosis in cell evolution, hierarchy theory, systems theory, game theory, sociobiology, and the selfish gene, the text is rich in autobiographical passages and biographies.
By presenting the human side of research, From Gaia to Selfish Genes reveals the social context and interactions, the motivations and range of cognitive styles that comprise the scientific endeavor. Ford Doolittle, and others underscore the importance of such diversity.
Connie Barlow is a science writer currently living in New York City. The scientists include: Robert Axelrod. Richard D. Ludwig von Bertalanffy.
Leo W. Francis Crick. Richard Dawkins. Ford Doolittle. Douglas Hofstadter. Julian Huxley. Leon J. Philip Kitcher. Richard C. James Lovelock. Lynn Margulis. Ashley Montagu. Leslie Orgel. Steven Rose. Carmen Sapienza. John Maynard Smith. Lewis Thomas. Gerald Weinberg. Robert Wright. The science writers include: Lawrence Joseph. Arthur Koestler.
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