んど g ど〃ど川 ac ん / 〃ど simulation. You ag 川ど what would happen if you did each of the alternatives open tO you 、 You set up a model in your head, not Of everything in the world, but Of the restricted set of entities which you think may be relevant. You may see them vividly in your mind's eye, or you may see and manipulate stylized abstrac— tions Of them. ln either case it is unlikely that somewhere laid out ln your brain IS an actual spatial model Of the events you are magining. But, just as in the computer, the details of how your brain represents its model of the world are less important than the fact that it is able tO use it to predict possible events. Survival machines which can simulate the future are one Jump ahead of survival machines WhO can only learn on the basis 0f overt trial and error. The trouble with overt trial is that it takes time and energy. The trouble with overt error is that it is often fatal. Simulation is both safer and faster. The evolution of the capacity to simulate seems to have cul- minated in subjective consclousness. Why this should have hap— pened is, t0 me, the most profound mystery facing modern biology. There is no reason to suppose that electromc computers are conscrous when they simulate, although we have to admit that in the future they may become so. Perhaps conscl()usness when the brain's simulation Of the world becomes so complete that it must include a model of itself. Obviously the limbs and bOdy Of a survival machine must constltute an lmportant part of its simulated world; presumably for the same kind of reason, the simulation itself could be regarded as part of the world to be simulated. Another word for this might indeed be 'self- awareness', but I don't find this a fully satisfying explanation of the evolution Of consclousness, and this is only partly because lt involves an infinite regress—if there IS a model of the model, why not a model of the model of the model . Whatever the philosophical problems raised by consclousness, for the purpose of this story it can be thought of as the culmina- t10n Of an evolutionary trend towards the emancrpation of sur- vival machines as executive decision—takers from their ultimate masters, the genes. NOt only are brains in charge of the day-to— day running Of survival-machine affairs, they have also acquired the ability to predict the future and act accordingly. They even have the power to rebel against the dictates of the genes, for

んど g ど〃ど ac ん / 〃ど were not umversally altruistic, and the computer was well on the way t0 dictatorship over the world before the hero eventually finished it Off with an axe. From our point of view, the interestmg questron ln what sense the Andromedans could be said to be manipulating events on Earth. They had no direct control over what the computer did from moment to moment; indeed they had no possible way of even knowing the computer had been built, since the informatlon would have taken 200 years to get back to them. The decisions and actions Of the computer were entirely its own. lt could not even refer back tO its masters for general policy instructions. All its instructions had tO be built-in in advance, because Of the lnviolable 200 year barrier. ln prlnciple, it must have been pro- grammed very much like a chess-playing computer, but with greater flexibility and capacity for absorbing local information. This was because the program had to be designed to work not Just on earth, but on any world possessing an advanced tech— nology, any 0f a set 0f worlds whose detailed conditions the Andromedans had no way of knowing. Just as the Andromedans had tO have a computer on earth tO take day-to-day decisions for them, our genes have to build a brain. But the genes are not only the Andromedans whO sent the COded instructions; they are alSO the instructlons themselves. The reason why they cannot manipulate our puppet strings directly is the same: time-lags. Genes work by controlling protein synthesis. This is a powerful way of manipulating the world, but it is slow. lt takes months of patiently pulling protein strings to build an embryo. The whole point about behaviour, on the other hand, is that it is fast. lt works on a tlme-scale not Of months but Of seconds and fractions Of seconds. Something happens in the world, an owl flashes overhead, a rustle in the long grass betrays prey, and in milliseconds nervous systems crackle intO actl()n, muscles leap, and someone's life is saved—or lOSt. Genes don't have reaction-tlmes like that. Like the Andromedans, the genes can only d0 their best 4 , 4 〃 by building a fast executive computer for themselves, and programmlng it in advance with rules and 'advice' tO cope with as many eventualities as they can anticipate'. But li , like the game 0f chess, offers t00 many different possible eventualities for a11 of them to be anticipated.

んど g ど〃ど川 ac ん ~ 〃ど Recently, computers have taken over large parts Of the simula- tion function, not only in military strategy, but in all fields where prediction Of the future IS necessary, fields like economlcs, ecology, sociology, and many others. The technique works like this. A model of some aspect of the world is set up in the com- puter. This does not mean that if you unscrewed the lid you would see a little miniature dummy inside with the same shape as the object simulated. ln the chess-playing computer there is no mental picture inside the memory banks recognizable as a chess board with knights and pawns sitting on it. The chess board and its current position would be represented by lists Of electronically COded numbers. 、 0 us a map IS a miniature scale model Of a part Of the world, compressed intO tWO dimenslons. ln a computer, a map would more probably be represented as a list 0f towns and other spots, each with tWO numbers—its latitude and longitude. But it does not matter hOW the computer actually hOlds its model of the world ⅲ its head, provided that it holds it in a form in which it can operate on lt, manipulate it, dO expenments with it and report back tO the human operators in terms which they can understand. Through the technique 0f simulation, model battles can be won or lOSt, simulated airliners fly or crash, econom1C policies lead tO prosperity or tO ruin. ln each case the whOle process goes on inside the computer ln a tiny fraction Of the time it would take in reallife. Of course there are good models 0f the world and bad ones, and even the good ones are only approxima- tions. NO amount Of simulation can predict exactly what will happen in reality, but a good simulation enormously preferable tO blind trial and error. Simulation could be called vicarious trial and error, a term unfortunately pre-empted long ago by rat psy- chologists. If simulation is such a good idea, we might expect that survival machines would have discovered it first. After all, they invented many 0f the 0ther techniques 0f human engineering long before we came on the scene: the focusing lens and the parabolic reflec- tor, frequency analysis Of sound waves, servo—control, sonar, buf— fer storage Of incomlng information, and countless Others with long names, whose details don't matter. What about simulation? WeII, when you yourself have a difficult decision to make involv- ing unknown quantities in the future, you dO go in for a form Of 62

118 お 4 川 / が〃 g birds—tend tO be great carers. A decision tO bear a new child is usually followed by a decision to care for it. lt is because bearing and caring SO Often go together in practice that people have muddled the two things up. But from the point of view of the selfish genes there is, as we have seen, no distinction in prmciple between caring for a baby brother and caring for a baby son. Both infants are equally closely related to you. If you have to choose between feeding one or the other, there is no genet1C reason why you should choose your own son. But on the other hand you cannot, by definition, bear a baby brother. You can only care for him once somebody else has brought him into the world. ln the last chapter we looked at how individual survival machines ideally should decide whether to behave altruistically towards other individuals who already exist. ln this chapter we ok at how they should decide whether to bring new individuals into the world. lt is over this matter that the controversy about group selec— tion', which I mentioned in Chapter 1 , has chiefly raged. This is because Wynne-Edwards, who has been mainly responsible for promulgating the idea 0f group selection, did so in the context 0f a theory 0f population regulation'. He suggested that individual animals deliberately and altruistically reduce their birth rates for the good of the group as a whole. This is a very attractive hypothesis, because it fits so well with what individual humans ought to d0. Mankind is having t00 many children. Population size depends upon four things: births, deaths, immigrations, and emigrations. Taking the world popula- tion as a WhOle, immigratlons and emigrations dO not occur, and we are 厄代 with births and deaths. SO long as the average number Of children per couple is larger than two surviving tO reproduce, the numbers Of babies born will tend tO increase over the years at an ever-accelerating rate. ln each generatlon the population, instead 0f going up by a fixed amount, increases by something more like a fixed proportion 0f the size that it has already reached. Since this size is itself getting bigger, the size of the increment gets bigger. If this kind of growth was allowed to go on unchecked, a population would reach astronomical proportions surprisingly quickly. lncidentally, a thing which is sometrmes not realized even by people wh0 worry about population problems is that population

7. Family planning lT is easy tO see why some people have wanted tO separate paren- tal care from the Other kinds Of kin-selected altruism. Parental care 100kS like an integral part Of reproduction whereas, for example, altruism toward a nephew is not. I think there really is an lmportant distinction hidden here, but that people have mis- taken what the distinction is. They have put reproduction and parental care on one side, and Other sorts Of altruism on the Other. But I wish tO make a distinction between み〃ツ g / 〃 g 〃どル市朝ノ″ 4 ム / 〃ーんどル 0 ノ , on the one hand, and び 4 〃 g ノらど工な行〃 g ノん / ノ〃 4 な on the other. I shall call these two activities respectively child- bearing and child-caring. An individual survival machine has t0 make tWO quite different sorts Of decisions, caring decisions and bearing decisions. I use the word decision tO mean unconscrous strategic move. The caring decisions are Of this form: is a child; its degree Of relatedness tO me IS SO and SO,• its chances Of dying if I d0 not feed it are such and such; shall I feed it?' Bearing decisions, on the other hand, are like this: 、 Shall I take whatever steps are necessary ln order tO bring a new individual intO the world; shall I reproduce?' TO some extent, carlng and bearing are bound tO compete with each Other for an individual's time and Other resources: the individual may have tO make a choice: 'Shall I care for this child or shall I bear a new one. Depending on the ecological details of the specles vanous nuxes Of caring and bearing strategles can be evolutionarily stable. The one thing which cannot be evolutionarily stable is a カ″尾 caring strategy. If all individuals devoted themselves t0 car- ing for existing children tO such an extent that they never brought any new ones into the world, the population would quickly become invaded by mutant individuals whO specialized in bear¯ ing. Caring can only be evolutionarily stable as part 0f a mixed strategy—at least some bearing has tO go on. The specles with which we are most familiar¯mammals and

7- 、んど g ど〃ど〃なれ、ん / 〃ど Plants have no need of the neurone, because they get their living without movlng around, but it is found in the great ma)()r- ity 0f animal groups. lt may have been 'discovered' early in animal evolution, and inherited by all groups, or it may have been rediscovered several times independently. Neurones are basically Just cells, with a nucleus and chromosomes like other cells. But their cell walls are drawn out ln long, thin, wire-like pr())ections. Often a neurone has one par- ticularly long 、 wire' called the axon. AIthough the width of an axon IS mlcroscopic, its length may be many feet: there are single axons which run the whole length 0f a giraffe's neck. The axons are usually bundled together in thick multi-stranded cables called nerves. These lead from one part of the body to another carrying messages, rather like trunk telephone cables. Other neurones have short axons, and are confined tO dense concentratlons Of nervous tissue called ganglia, or, when they are very large, brains. Brains may be regarded as analogous in function tO computers. They are analogous in that both types 0f machine generate complex pat- terns Of output, after analysis Of complex patterns Of input, and after reference tO stored informatl()n. The maln way in which brains actually contribute to the success Of survival machines iS by controlling and coordinating the contractions 0f muscles. TO d0 this they need cables leading tO the muscles, and these are called motor nerves. But this leads tO efficient preservation of genes only if the timing Of muscle contractlons bears some relation tO the tinung Of events in the outside world. lt is important tO contract the jaw muscles only when the Jaws contaln something worth biting, and tO contract the leg muscles in runnlng patterns only when there is something worth running towards or away from. For thiS reason, natural selection favoured animals which became equipped with sense organs, devices whICh translate patterns Of physical events in the outside world intO the pulse COde Of the neurones. The brain is connected tO the sense organs—eyes, ears, taste-buds etc. —by means 0f cables called sensory nerves. The workings 0f the sen- sory systems are particularly baffling, because they can achieve far more sophisticated feats Of pattern-recognition than the best and most expensive man—made machines; if thiS were not SO, all typists would be redundant, superseded by speech-recogmnng 52

intermediate generatlon without being merged with other genes. If genes continually blended with each other, natural selection as we now understand it would be impossible. lncidentally, this was proved in Darwin's lifetime, and it caused Darwin great worry since in those days it was assumed that heredity was a blending process. Mendel's discovery had already been published, and it could have rescued Darwin, but alas he never knew about lt: nobody seems to have read it until years after Darwin and Mendel had both died. Mendel perhaps did not realize the sig- nificance Of his findings, otherwise he might have written to Darwin. Another aspect of the particulateness of the gene is that it does not grow senile; it is no more likely tO die when it a million years 01d than when it is only a hundred. lt leaps from body to body down the generations, manipulating body after body in its own way and for itS own ends, abandoning a successl()n of mortal bodies before they sink in senility and death. The genes are the immortals, or rather, they are defined as genetic entlties which come close to deserving the title. Ⅵ第 , the individual survival machines in the world, can expect to live a few more decades. But the genes in the world have an expectation of life which must be measured not in decades but in thousands and millions 0f years. ln sexually reproducing species, the individual is t00 large and t00 temporary a genetic unit tO qualify as a significant unit of natural selection. The group Of individuals is an even larger umt. Genetically speaking, individuals and groups are like clouds in the sky or dust-storms in the desert. They are temporary aggrega- t10ns or federations. They are not stable through evolutionary time. Populations may last a long while, but they are constantly blending with other populations and so losing their identitv. They are also subject to evolutionary change from within. A population is not a discrete enough entity to be a unit of natural selection, not stable and unitary enough to be 'selected' in pref 、 er- ence tO another population. An individual body seems discrete enough while it lasts, but alas, hOW long is that? Each individual is unique. You cannot get evolution by selecting between entlties when there is only one copy Of each entity! Sexual reproduction is not replication. Just as

214 ノど . ・一んど〃どど第 / な 4 memes which are also being selected. The meme po 司 therefore comes tO have the attributes of an evolutionarily stable set, which new memes find it hard to invade. I have been a bit negative about memes, but they have their cheerful side as well. When we die there are two things we can leave behind us: genes and memes. Ⅵ were built as gene mach- lnes, created tO pass on our genes. But that aspect 0f us will be forgotten in three generations. Your child, even your grandchild, may bear a resemblance tO you, perhaps in facial features, ln a talent for muSIC, in the colour of her hair. But as each generation passes, the contribution Of your genes is halved. lt does not take long t0 reach negligible proportions. Our genes may be immortal but the CO / ん〃 Of genes which is any one of us is bound to crumble away. EIizabeth I I is a direct descendant of WiIliam the Conqueror. Yet it is quite probable that she bears not a single one of the old king's genes. We should not seek immortality in reproduction. But if you contribute to the world's culture, if you have a good idea, compose a tune, mvent a sparking plug, write a poem, lt may live on, lntact, long after your genes have dissolved in the C01 mon POOI. Socrates may or may not have a gene or tWO alive in the world today, as G. C. WiIIiams has remarked, but who cares? The meme—complexes Of Socrates, Leonard0, Copermcus, and Marcon1 are still going strong. However speculative my development of the theory of memes may be, there is one serious point which I would like to em- phasize once again. This is that when we lOOk at the evolution Of cultural traits and at their survival value, we must be clear ルん 0 記 survival we are talking about. Biologists, as we have seen, are accustomed t0 looking for advantages at the gene level ()r the individual, the group, or the species level according to taste). What we have not previously considered is that a cultural trait may have evolved in the way that it has, simply because it IS Ⅵ do not have to 100k for conventional biological survival values Of traits like religion, musrc, and ritual dancing, though these may also be present. Once the genes have provided their survival machines with brains which are capable Of rapid imita— tion, the memes will automatically take over. We dO not even

外イどお . ・一んどれどど 2 / 耘 4 ー 0 207 as living structures, notJust metaphorically but technically. When you plant a fertile meme ln my mind you literally parasitize my brain, turning intO a vehicle for the meme's propagation in Just the way that a virus may parasitize the genetic mechanism Of a host cell. And this isn'tjust a way 0f talking—the meme for, say, 'belief in li after death' is actually realized physically, millions Of times over, as a structure in the nervous systems Of individual men the world over. Consider the idea of God. We do not know how it arose in the meme pool. Probably it originated many times by independent mutation'. ln any case, lt is very Old indeed. HOW does it replicate itself? By the spoken and written word, aided by great music and great art. Why does it have such high survival value? Remember that 'survival here does not mean value for a gene 2 gene POOI, but value for a meme ln a meme POOI. The question really means: What is it about the idea 0f a god which gives it lts stability and penetrance in. the cultural envlronment? The survival value of the god meme in the meme pool results from its great psychological appeal. lt provides a superficially plausible answer tO deep and troubling questions about exrstence. lt suggests that inJustices in this world may be rectified in the next. The 'everlasting arms' hOld out a cushion against our own inadequacies which, like a doctor's placebo, is none the less effec- tive for being imaginary. These are some Of the reasons why the idea of God is copied so readily by successrve generations 0f individual brains. God exists, if only in the form 0f a meme with high survival value, or infective power, in the envtronment provided by human culture. Some Of my colleagues have suggested tO me that this account of the survival value of the god meme begs the question. ln the last analysis they wish always t0 go back to 'biological advantage'. To them it is not good enough to say that the idea of a god has great psychological appeal'. They want t0 know ル it has great psychological appeal. Psych010gical appeal means appeal t0 brains, and brains are shaped by natural selection Of genes ln gene-pools. They want t0 find some way in which having a brain like that improves gene survival. I have 靆 lot of sympathy with this attitude, and I d0 not doubt that there are genetic advantages ln our having brains Of the kind

物″“ ra なんァ厖 , / ' ″ 0 〃ッハ 191 estimate Of the sex ratiO. 、・ OW the male and m 引 e reproductives are, III many specles, very unequal in SIZe. things smce, as we saw in the prevrous chapter, the Fisher cal- culations about optimal sex ratiO strictly apply, not tO 〃〃みどハ Of males and females, but tO イ〃 4 〃行り′ OJ 、 / 〃 0 ど襯ど〃ー ln males and females. Trivers and Hare made allowance for this bY weighing them. They tOOk 20 species Of ant and estimated the sex ratiO in terms Of investment reproductives. They found a rather con- vincingly close fit t0 the 3 : 1 female t0 male ratio predicted bY the theory that the workers are running the shOW for their own benefit. lt seems then that in the ants studied, the conflict Of interests IS won' by the workers. This is not t00 surprismg smce worker b()dies, being the guardians Of the nurseries, have more power ln practical terms than queen bOdies. Genes trying tO manipulate the world through queen bodies are outmanoeuvred bY genes manipulating the world through worker bOdies. lt is interesting tO 100k around for some special circumstances ln WhiCh we might expect queens tO have more practical power than workers. and Hare realized that there was such a circumstance which could be used as a critical test Of the theory. This arises from the fact that there are some species Of ant which take slaves. The workers Of a slave—making species either d0 no ordinary work at all or are rather bad at it. What they are good at is gomg on slaving raids. True warfare in which large rival armies fight tO the death is known on in man and in social lnsects. ln many species Of ants the specialized caste Of workers known as soldiers have formidable fighting Jaws' and devote their time tO fighting for the colony against Other ant armies. Slaving raids are )ust a particular kind Of war effort. The slavers mount an attack on a nest Of ants belonging tO a different species' attempt t0 kill the defending workers or soldiers' and carry 0ff the unhatched young. These young ones hatch out in the nest 0f their captors. They dO not'realize' that they are slaves and they set tO work following their built-in nervous programs' doing all the duties that they would normally perform in their own nest. The slave- making workers or soldiers go on further slaving expeditions while the slaves stay at home and get on with the everyday business Of running an ants' nest, cleaning, foraging' and caring for the brood.