December 20, 2014

The Selfish Gene by Richard Dawkins

The Selfish Gene by Richard Dawkins

Let us understand what our own selfish genes are up to, because we may then at least have the chance to upset their designs, something that no other species has ever aspired to. I shall argue that the fundamental unit of selection and therefore of self-interest, is not in the species, nor the group, nor even, strictly the individual. It is the gene, the unit of heredity.

The account of the origin of life that I shall give is necessarily speculative. We don’t know what chemical raw materials were abundant on earth before the coming of life, but among the plausible possibilities are water, carbon dioxide, methane and ammonia. Under further influence of energy such as ultraviolet light from the sun, they combined into larger molecules. At some point a particularly remarkable molecule was formed by accident. We will call it the replicator. It had extraordinary property of being able to create copies of itself. 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. 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.

The plans for building blocks a human body is spelt out in 46 volumes (23 pairs of chromosomes). Let us call them as volume 1a and volume 1 b, 2a & 2b... 23a & 23b. Volume 1a, 2a...23a came say from father and the other volumes (1b, 2b...23b) came from mother. The paired chromosomes do not spend all their lives physically in contact with each other or even near each other. Sometimes the two alternative pages are identical, but in their cases, they differ. If they make contradictory recommendations, what does the body do? Answer varies. Sometimes one reading prevails over the other. A gene that is ignored in this way is called recessive and the opposite of a recessive gene is a dominant gene.

Apart from 23 pairs of chromosomes, there is another kind of division called meiosis. This occurs only in the production of the sex cells; the sperms or eggs.

We have already asked what the most general attributes of a good gene are and we decided that selfishness was one of them. But another quality that successful genes will have is a tendency to postpone the death of their survival machines at least until after reproduction.  A gene that makes its possessors die is called a lethal gene. A semi lethal gene has some debilitating effect, such that it makes a death from other more probable. Any gene exerts its maximum effect on bodies at some particular stage of life and lethal and semi lethal are not exceptions. Most genes exert their influence during foetal life, others during childhood, others during young adulthood, others in middle age, and yet others in old age.

Early acting lethal genes will tend to be removed from the gene pool and a late acting lethal will be more stable in the gene pool (e.g. a gene that made young children develop cancer would not be passed on to any off-springs. Selection will favor genes that have the effect of postponing the operation of other, lethal genes and it will also favor genes that have the effect of hastening the effect of good genes. If we want to increase the human lifespan, there are two general ways in which we could do it. Firstly we could ban reproduction before a certain age, say forty. After some centuries of this the minimum age limit would be raised to fifty and so on. It is conceivable that human longevity would be pushed up to several centuries by this means,. Secondly, we could try to ‘fool’ genes into thinking that the body they are sitting in is younger than it really is. In practice this would mean identifying changes in the internal chemical environment of a body that take place during aging.

The existence of sexual reproduction and crossing-over is more difficult to justify. Female greenflies can bear live, fatherless, female offspring, each one containing all the genes of its mother (incidentally, an embryo in her mother’s womb may have an even smaller embryo inside her own womb. So a greenfly female may give birth to a daughter and a granddaughter simultaneously, both of them being equivalent to her own identical twins). Manny plants propagate vegetatively by sending out suckers (e.g. elm trees) If greenflies and elm trees don’t do it why do the rest of us go to such lengths to mix our genes up with somebody else’s before we make a baby? The evolution of sex results from the fact that number of his genes that survive. In these terms, sex appears paradoxical because it is an inefficient way for an individual to propagate her genes; each child has only 50% of the individuals’ genes, the other 50 percent has only 50 percent being provided by the sexual partner.

Animals Became active go-getting gene vehicles: gene machines. Plants move, but very slowly. Animals on the other hand, have evolved ways of moving hundreds of thousands f time faster. Moreover the movements they make are reversible and repeatable an indefinite number of times. The gadget that animals evolved to achieve rapid movement was the muscle. Muscles are engines which like the steam engine and the internal combustion engine, use energy stores in chemical fuel to generate mechanical movement.

The basic unit of biological computers, the nerve cell or neuron. Plants have no need of the neuron, because they get their living without moving around, but it is found in the great majority of animal groups. . .

Whenever a system of communication evolves, there is always the danger that some will exploit the system for their own ends. Brought up as we have been on the good of the species, view of evolution, we naturally think first of liars and deceivers as belonging to different species: predators, prey, parasites and so on. However, we must expect lie3s and deceit and selfish exploitation of communication to arise whenever the interests of the genes of different individuals diverge. This will include f the same species. As we shall see, we must even expect that children will deceive their parent, that husbands will cheat on wives and that brother will lie to brother.

An evolutionary stable strategy (ESS) defined as a strategy which, if most members of a population adopt it, cannot be bettered by an alternative strategy. Hawks always fight as hard and as unrestrainedly as they can, retreating only when seriously injured. Doves merely threaten in a dignified conventional way, never hurting anybody. If hawk fights a dove the dove quickly runs away and so does not get hurt. If a hawk fights a hawk, they go on until one of them seriously injured or dead. If dove meets a dove nobody gets hurt; they go on posturing at each other for a long time until one of them tires o decides not to bother anymore and therefore backs down. What we want to know either hawk or dove is an evolutionary stable strategy. A retaliator plays like a dove at the beginning of every fight; however if his opponent attacks him, he retaliates. Another conditional is bully who goes around behaving like a hawk until somebody hits back and then he immediately runs away (like dove). Out of these five types, retaliator emerges as evolutionary stable.

In many species a mother can be more sure of her young than a father can. The mother lays the visible, tangible egg, or bears the child. She has a good chance of knowing for certain the bearers of her own genes. The poor father is much more vulnerable to deception. It is therefore to be expected that fathers will put less effort than mothers into caring for young. Similarly maternal grandmothers can be more sure of their grandchildren than paternal grandmothers. Similarly uncles on the mother’s side should be more interested in the welfare of nephews and nieces than uncles on the father's side.

Individual parents practice family planning, but in the sense that they optimize their birth-rates rather than restrict them for public good. They try to maximize the number of surviving children that they have and this means having neither too many babies nor too few. Gens that make an individual have too many babies tend not to persist in the gene pool, because children containing such genes tend not to survive to adulthood.

It is strongly to be expected on evolutionary grounds that where sexes differ, it should be expected to be the males that advertise and females that are drab, Modern western man is undoubtedly exceptional in this respect. It is true that on average, our society the equivalent of the peacock’s tail is exhibited by female not by the male. Women paint their faces and glue on false eyelashes. Women seem to be interested in their own personal appearance and they are encouraged in this by their magazines and journals. Men’s magazines are less preoccupied with male sexual attractiveness and a man who is unusually interested in his own dress and appearance is apt to arouse suspicion both among men and among women. When a woman is described in conversation, it is quite likely that her sexual attractiveness or lack of it will be prominently mentioned. This is true whether the speaker is a man or women. When a man is described, the adjectives used are much more likely to have nothing to do with sex. Faced with these facts, a biologist would be forced to suspect that he was looking at a society in which females compete for males rather than vice versa. In the case of birds of paradise, we decided that females are drab because they do not need to compete for males. Males are bright and ostentatious because females are in demand and can afford to be choosy. The reason female birds of paradise are in demand is that eggs are a more scarce resource than sperms. What happened i n modern western man? Has the male really become the sought-after sex, the one that is in demand, the sex that can afford to be choosy?

A long memory and a capacity for individual recognition are well developed in man. We might therefore expect reciprocal altruism to have played an important part in human evolution. Trivers goes so far as to suggest that many of our psychological characteristics - envy, guilt, gratitude, sympathy etc. - have been shaped by natural selection for improved ability to cheat, to detect cheats, and to avoid being thought to be a cheat. Of particular interest are subtle cheats who appear to be reciprocating, but who consistently pay back slightly less than they receive. It is even possible that man’s swollen brain, and his predisposition to reason mathematically, evolved as a mechanism of ever devious cheating and ever more penetrating detection of cheating in others. Money is a formal token of delayed reciprocal altruism.

The fundamental unit, the prime mover of life is the replicator.  A replicator is anything in the universe of which copies are made. Replicators come into existence in the first place, by chance, by the random jostling of smaller particles. Once a replicator has come into existence it is capable of generating an indefinitely large set of copies of itself. No copying process is perfect, however and the population is replicators come to include varieties that differ from one another. Some of these varieties turn out to have lost the power of self- replication, and their kind ceases to exist when they themselves cease to exist. Others can still replicate, but less effectively. Yet other varieties happen to find themselves in possession of new tricks: they turn out to be even better self-replicators than their predecessors and contemporaries. it is their descendants that come to dominate the population,. As time goes by, the world becomes filled with the most powerful and ingenious replicators. Certainly in principle and also in fact, the gene reaches out through the individual body wall and manipulates objects in the world outside, some of them inanimate, some of them other living beings, some of them a long way away. The only kind of entity that has to exist in order for life to arise anywhere in the universe is the immortal replicator.

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