If you tell her about witches
changing
princes into frogs, she will believe you.
Richard-Dawkins-The-Devil-s-Chaplain
'You are talking just like him; your voice sounds exactly like his.
' I had, if only briefly, 'inherited' intonations and manners of speech from an admired, and now greatly missed, teacher.
Years later, when I became a tutor myself, I taught a young woman who affected an unusual habit. When asked a question which required deep thought, she would screw her eyes tight shut, jerk her head down to her chest and then freeze for up to half a minute before looking up, opening her eyes, and answering the question with fluency and intelligence. I was amused by this, and did an imitation of it to divert my colleagues after dinner. Among them was a distinguished Oxford philosopher. As soon as he saw my imitation, he immediately said: 'That's Wittgenstein! Is her surname by any chance? ' Taken aback, I said that it was. T thought so,' said my colleague. 'Both her parents are devoted followers of Wittgenstein. ' The gesture had passed from the great philosopher, via one or both of her parents, to my pupil. I suppose that, although my further imitation was done in jest, I must count myself a fourth generation transmitter of the gesture. And who knows where Wittgenstein got it?
Imitation is how a child learns its particular language rather than some other language. It is why people speak more like their own parents than like other people's parents. It is why regional accents, and on a longer timescale separate languages, exist. It is why religions persist along family lines rather than being chosen afresh in every generation. There is at least a superficial analogy to the longitudinal transmission of genes down generations, and to the horizontal transmission of genes in
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viruses. Without prejudging the issue of whether the analogy is a fruitful one, if we want even to talk about it we had better have a name for the entity that might play the role of gene in the transmission of words, ideas, faiths, mannerisms and fashions. Since 1976, when the word was coined, increasing numbers of people have adopted the name 'meme' for the postulated gene analogue.
The compilers of the Oxford English Dictionaries operate a sensible criterion for deciding whether a new word shall be canonized by inclusion. The aspirant word must be commonly used without needing to be denned and without its coining being attributed. To ask the metamemetic question, how widespread is 'meme', a far from ideal, but nevertheless convenient method of sampling the meme pool, is provided by the World Wide Web. I did a quick search of the web on the day of writing this, which happened to be 29 August 1998. 'Meme' is mentioned about half a million times, but that's a ridiculously high figure, obviously confounded by various acronyms and the French meme. The adjectival form 'memetic' is genuinely exclusive, and it clocked up 5042 mentions. To put this number into perspective, I compared a few other recently coined words or fashionable expressions. Spin doctor (or spin-doctor) gets 1412 mentions, dumbing down 3905, docudrama (or docu-drama) 2848, sociobiology 6679, catastrophe theory 1472, edge of chaos 2673, wannabee 2650, zippergate 1752, studmuffin 776, post-structural (or poststructural) 577, extended phenotype 515, exaptation 307. Of the 5042 mentions of memetic, more than 90 per cent make no mention of the origin of the word, which suggests that it does indeed meet the OED's criterion. And the Oxford Dictionary now does contain the following definition: meme: 'a self-replicating element of culture, passed on by imitation. '
Further searching of the internet reveals a newsgroup talking-shop, 'alt. memetics', which has received about 12,000 postings during the past year. There are on-line articles on, among many other things, 'The New Meme', 'Meme, Counter-meme', 'Memetics: a Systems Metabiology', 'Memes, and Grinning Idiot Press', 'Memes, Metamemes and Polities', 'Cryonics, religions and memes', 'Selfish Memes and the evolution of cooperation', and 'Running down the Meme'. There are separate web pages on 'Memetics', 'Memes', 'The C Memetic Nexus', 'Meme theorists on the web', 'Meme of the week', 'Meme Central', 'Arkuat's Meme Workshop', 'Some pointers and a short introduction to memetics', 'Memetics Index' and 'Meme Gardening Page'. There is even a new religion (tongue in cheek, I think), called the 'Church of Virus', complete with its own list of Sins and Virtues, and its own patron saint (Saint
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? Charles Darwin, canonized as 'perhaps the most influential memetic engineer of the modern era') and I was alarmed to discover a passing reference to 'Saint Dawkins'.
Memes travel longitudinally down generations, but they travel hori- zontally too, like viruses in an epidemic. Indeed, it is largely horizontal epidemiology that we are studying when we measure the spread of a word like memetic, docudrama or studmuffin over the internet. Crazes among schoolchildren provide particularly tidy examples. When I was about nine, my father taught me to fold a square of paper to make an origami Chinese junk. It was a remarkable feat of artificial embryology, passing through a distinctive series of intermediate stages: catamaran with two hulls, cupboard with doors, picture in a frame, and finally the junk itself, fully seaworthy or at least bathworthy, complete with deep hold, and two flat decks each surmounted by a large, square-rigged sail. The point of the story is that I went back to school and infected my friends with the skill, and it then spread around the school with the speed of the measles and pretty much the same epidemiological time- course. I don't know whether the epidemic subsequently jumped to other schools (a boarding school is a somewhat isolated backwater of the meme pool). But I do know that my father himself originally picked up the Chinese Junk meme during an almost identical epidemic at the same school 25 years earlier. The earlier virus was launched by the school matron. Long after the old matron's departure, I had reintroduced her meme to a new cohort of small boys.
Before leaving the Chinese junk, let me use it to make one more point. A favourite objection to the meme/gene analogy is that memes, if they exist at all, are transmitted with too low fidelity to perform a gene-like role in any realistically Darwinian selection process. The difference between high fidelity genes and low fidelity memes is assumed to follow from the fact that genes, but not memes, are digital. I am sure that the details of Wittgenstein's mannerism were far from faithfully reproduced when I imitated my pupil's imitation of her parents' imitation of Wittgenstein. The form and timing of the tic undoubtedly mutated over the generations, as in the childhood game of Chinese Whispers (Americans call it Telephone).
Suppose we assemble a line of children. A picture of, say, a Chinese junk is shown to the first child, who is asked to draw it. The drawing, but not the original picture, is then shown to the second child, who is asked to make her own drawing of it. The second child's drawing is shown to the third child, who draws it again, and so the series proceeds until the twentieth child, whose drawing is revealed to everyone and
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compared with the first. Without even doing the experiment, we know what the result will be. The twentieth drawing will be so unlike the first as to be unrecognizable. Presumably, if we lay the drawings out in order, we shall notice some resemblance between each one and its immediate predecessor and successor, but the mutation rate will be so high as to destroy all semblance after a few generations. A trend will be visible as we walk from one end of the series of drawings to the other, and the direction of the trend will be degeneration. Evolutionary geneticists have long understood that natural selection cannot work unless the mutation rate is low. Indeed, the initial problem of overcoming the fidelity barrier has been described as the Catch-22 of the Origin of Life. Darwinism depends upon high fidelity gene replication. How then can the meme, with its apparently dismal lack of fidelity, serve as quasi-gene in any quasi-Darwinian process?
It isn't always as dismal as you think, and high fidelity is not necessarily synonymous with digital. Suppose we set up our Chinese Whispers game again, but this time with a crucial difference. Instead of asking the first child to copy a drawing of a junk, we teach her, by demonstration, to make an origami model of a junk. When she has mastered the skill and made her own junk, the first child is asked to turn round to the second child and teach him how to make one. So the skill passes down the line to the twentieth child. What will be the result of this experiment? What will the twentieth child produce, and what shall we observe if we lay the 20 efforts out in order along the ground? I haven't done it, but I will make the following confident prediction, assuming that we run the experiment many times on different groups of 20 children. In several of the experiments, a child somewhere along the line will forget some crucial step in the skill taught him by the previous child, and the line of phenotypes will suffer an abrupt macro- mutation which will presumably then be copied to the end of the line, or until another discrete mistake is made. The end result of such mutated lines will not bear any resemblance to a Chinese junk at all. But in a good number of experiments the skill will correctly pass all along the line, and the twentieth junk will be no worse and no better, on average, than the first junk. If we then lay the 20 junks out in order, some will be more perfect than others, but imperfections will not be copied on down the line. If the fifth child is hamfisted and makes a clumsily asymmetrical or floppy junk, his quantitative errors will be corrected if the sixth child happens to be more dexterous. The 20 junks will not exhibit a progressive deterioration in the way that the 20 drawings of our first experiment undoubtedly would.
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? Why? What is the crucial difference between the two kinds of experi- ment? It is this. Inheritance in the drawing experiment is Lamarckian (Susan Blackmore calls it 'copying the product'). In the origami experiment it is Weismannian (Blackmore's 'copying the instructions'). In the drawing experiment, the phenotype in every generation is also the genotype - it is what is passed on to the next generation. In the origami experiment, what passes to the next generation is not the paper phenotype but a set of instructions for making it. Imperfections in the execution of the instructions result in imperfect junks (phenotypes) but they are not passed on to future generations: they are non-memetic. Here are the first five instructions in the Weismannian meme-line of instructions for making a Chinese junk:
1. Take a square sheet of paper and fold all four corners exactly into the middle.
2. Take the reduced square so formed, and fold one side into the middle.
3. Fold the opposite side into the middle, symmetrically.
4. In the same way, take the rectangle so formed, and fold its two ends
into the middle.
5. Take the small square so formed, and fold it backwards, exactly
along the straight line where your last two folds met.
. . . And so on, through 20 or 30 instructions of this kind. These instruc- tions, though I would not wish to call them digital, are potentially of very high fidelity, just as if they were digital. This is because they all make reference to idealized tasks like 'fold the four corners exactly into the middle'. If the paper is not exactly square, or if a child folds ineptly so that, say, the first corner overshoots the middle and the fourth corner undershoots it, the junk that results will be inelegant. But the next child in the line will not copy the error, for she will assume that her instructor intended to fold all four corners into the exact centre of a perfect square. The instructions are self-normalizing. The code is error- correcting.
The instructions are more effectively passed on if verbally reinforced, but they can be transmitted by demonstration alone. A Japanese child could teach an English one, though neither has a word of the other's language. In the same way, a Japanese master carpenter could convey his skills to an equally monoglot English apprentice. The apprentice would not copy obvious mistakes. If the master hit his thumb with a hammer, the apprentice would correctly guess, even without
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understanding the Japanese for '** **** **! ', that he meant to hit the nail. He would not make a Lamarckian copy of the precise details of every hammer blow, but copy instead the inferred instruction: drive the nail in with as many blows of your hammer as it takes your arm to achieve the same idealized end result as the master has achieved with his - a nail-head flush with the wood.
I believe that these considerations greatly reduce, and probably remove altogether, the objection that memes are copied with insufficient fidelity to be compared with genes. For me, the quasi-genetic inheritance of language, and of religious and traditional customs, teaches the same lesson. Another objection is that we don't know what memes are made of or where they reside. Memes have not yet found their Watson and Crick; they even lack their Mendel. Whereas genes are to be found in precise locations on chromosomes, memes presumably exist in brains, and we have even less chance of seeing one than of seeing a gene (though the neurobiologist Juan Delius has pictured his conjecture of
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whatamememightlooklike ). Aswithgenes,wetrackmemesthrough
populations by their phenotypes. The 'phenotype' of the Chinese junk meme is made of paper. With the exception of 'extended phenotypes' such as beaver dams and caddis larva houses, the phenotypes of genes are normally parts of living bodies. Meme phenotypes seldom are.
But it can happen. To return to my school again, a Martian geneticist, visiting the school during the morning cold bath ritual, would have unhesitatingly diagnosed an 'obvious' genetic polymorphism. About 50 per cent of the boys were circumcised and 50 per cent were not. The boys, incidentally, were highly conscious of the polymorphism and we classified ourselves into Roundheads versus Cavaliers (I have recently read of another school in which the boys even organized themselves into two football teams along the same lines). It is, of course, not a genetic but a memetic polymorphism. But the Martian's mistake is completely understandable; the morphological discontinuity is of exactly the kind that one normally expects to find produced by genes.
In England at the time, infant circumcision was a medical whim, and the roundhead/cavalier polymorphism at my school probably owed less to longitudinal transmission than to differing fashions in the various hospitals where we happened to have been born - horizontal memetic transmission yet again. But through most of history circumcision has been longitudinally transmitted as a badge of religion (ofparents' religion I hasten to point out, for the unfortunate child is normally too young to know his own religious mind). Where circumcision is religiously or traditionally based (the barbaric custom of female 'circumcision'
? always is), the transmission will follow a longitudinal pattern of heredity, very similar to the pattern for true genetic transmission, and often persisting for many generations. Our Martian geneticist would have to work quite hard to discover that no genes are involved in the genesis of the roundhead phenotype.
The Martian geneticist's eyes would also pop out on stalks (assuming they weren't on stalks to begin with) at the contemplation of certain styles of clothing and hairdressing, and their inheritance patterns. The black skullcapped phenotype shows a marked tendency towards longi- tudinal transmission from father to son (or it may be from maternal grandfather to grandson), and there is clear linkage to the rarer pigtail- plaited sideburn phenotype. Behavioural phenotypes such as genuflecting in front of crosses, and facing east to kneel five times per day, are inherited longitudinally too, and are in strong linkage disequilibrium with the previously mentioned phenotypes, as is the red-dot-on- forehead phenotype, and the saffron robes/shaven head linkage group.
Genes are accurately copied and transmitted from body to body, but some are transmitted at greater frequency than others - by definition they are more successful. This is natural selection, and it is the explana- tion for most of what is interesting and remarkable about life. But is there a similar meme-based natural selection? Perhaps we can use the internet again to investigate natural selection among memes? As it happens, around the time the word meme was coined (actually a little
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later), a rival synonym, 'culturgen', was proposed. Today, culturgen is
mentioned 20 times on the World Wide Web, compared with meme's 5042. Moreover, of those 20, 17 also mention the source of the word, falling foul of the Oxford Dictionary's criterion. Perhaps it is not too fanciful to imagine a Darwinian struggle between the two memes (or culturgens), and it is not totally silly to ask why one of them was so much more successful. Perhaps it is because meme is a monosyllable similar to gene, which therefore lends itself to quasi-genetic sub- coinings: meme pool (352), memotype (58), memeticist (163), memeoid (or memoid) (28), retromeme (14), population memetics (41), meme complex (494), memetic engineering (302) and metameme (71) are all listed in a 'Memetic Lexicon' on the World Wide Web (the numbers in brackets count the mentions of each word on the World Wide Web on my sampling day). Culturgen-based equivalents would be less snappy. Or the success of meme against culturgen may have been initially just a non-Darwinian matter of chance - memetic drift (85) - followed by a self-reinforcing positive feedback effect ('unto every one that hath shall be given, and he shall have abundance: but from him
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that hath not shall be taken away even that which he hath' (Matthew 25:29).
I have mentioned two favourite objections to the meme idea: memes have insufficient copying fidelity, and nobody really knows what a meme physically is. A third is the vexed question of how large a unit deserves the name meme. Is the whole Roman Catholic Church one meme, or should we use the word for one constituent unit, such as the idea of incense or the transubstantiation? Or for something in between? The answer is to be found in the concept of the meme-complex or 'memeplex'.
Memes, like genes, are selected against the background of other memes in the meme pool. The result is that gangs of mutually compatible memes - coadapted meme complexes or memeplexes - are found cohabiting in individual brains. This is not because selection has chosen them as a group, but because each separate member of the group tends to be favoured when its environment happens to be dominated by the others. An exactly similar point can be made about genetic selection. Every gene in a gene pool constitutes part of the environmental background against which the other genes are naturally selected, so it's no wonder natural selection favours genes that 'cooperate' in building those highly integrated and unified machines called organisms. By analogy with coadapted gene complexes, memes, selected against the background of each other, 'cooperate' in mutually supportive memeplexes - supportive within the memeplex but hostile to rival memeplexes. Religions may be the most convincing examples of memeplexes, but they are by no means the only ones.
I am occasionally accused of having backtracked on memes; of having lost heart, pulled in my horns, had second thoughts. The truth is that my first thoughts were more modest than some memeticists might have wished. For me, the original mission of the meme was negative. The word was introduced at the end of a book which other- wise must have seemed entirely devoted to extolling the selfish gene as the be-all and end-all of evolution, the fundamental unit of selection, the entity in the hierarchy of life which all adaptations could be said to benefit. There was a risk that my readers would misunderstand the message as being necessarily about genes in the sense of DNA molecules. On the contrary, DNA was incidental. The real unit of natural selection was any kind of replicator, any unit of which copies are made, with occasional errors, and with some influence or power over their own probability of replication. The genetic natural selection identified by neo-Darwinism as the driving force of evolution on this planet was only
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? a special case of a more general process that I came to dub 'Universal Darwinism'. Perhaps we'd have to go to other planets in order to discover any other examples. But maybe we didn't have to go that far. Could it be that a new kind of Darwinian replicator was even now staring us in the face? This was where the meme came in.
I would have been content, then, if the meme had done its work of simply persuading my readers that the gene was only a special case: that its role in the play of Universal Darwinism could be filled by any entity in the universe answering to the definition of Replicator. The original didactic purpose of the meme was the negative one of cutting the selfish gene down to size. I became a little alarmed at the number of my readers who took the meme more positively as a theory of human culture in its own right - either to criticize it (unfairly, given my original modest intention) or to carry it far beyond the limits of what I then thought justified. This was why I may have seemed to backtrack.
But I was always open to the possibility that the meme might one day be developed into a proper hypothesis of the human mind, and I did not know how ambitious such a thesis might turn out to be. I am delighted that others are now undertaking it. *
CHINESE JUNK AND CHINESE WHISPERS
*In addition to Susan Blackmore's The Meme Machine, other books that make heavy use of the meme idea are R. Brodie, Virus of the Mind: the New Science of the Meme (Seattle, Integral Press, 1996) (not to be confused with my essay (see over page), which was published three years earlier); A. Lynch, Thought Contagion: How Belief Spreads Through Society (New York, Basic Books, 1998); J. M. Balkin, Cultural Software (New Haven, Yale University Press, 1998); H. Bloom, The Lucifer Principle (Sydney, Allen & Unwin, 1995); Robert Aunger, The Electric Meme (New York, Simon & Schuster, 2002); Kevin Laland and Gillian Brown, Sense and Nonsense (Oxford, Oxford University Press, 2002); and Stephen Shennan, Genes, Memes and Human History (London, Thames and Hudson, 2002). A turning point in the fortunes of the meme was its adoption and development by Daniel Dennett as a cornerstone of his theory of the evolution of the mind, especially in his two books Consciousness Explained (Boston, Little Brown, 1991) and Darwin's Dangerous Idea (New York, Simon & Schuster, 1995).
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? 32 Viruses of the Mind77
The haven all memes depend on reaching is the human mind, but a human mind is itself an artifact created when memes restructure a human brain in order to make it a better habitat for memes. The avenues for entry and departure are modified to suit local conditions, and strengthened by various artificial devices that enhance fidelity and prolixity of replication: native Chinese minds differ dramatically from native French minds, and literate minds differ from illiterate minds. What memes provide in return to the organisms in which they reside is an incalculable store of advantages - with some Trojan horses thrown in for good measure . . .
78 Daniel Dennett
Duplication-Fodder
A beautiful child close to me, six and the apple of her father's eye, believes that Thomas the Tank Engine really exists. She believes in Father Christmas, and when she grows up her ambition is to be a tooth fairy. She and her schoolfriends believe the solemn word of respected adults that tooth fairies and Father Christmas really exist. This little girl is of an age to believe whatever you tell her.
If you tell her about witches changing princes into frogs, she will believe you. If you tell her that bad children roast forever in hell, she will have nightmares. I have just discovered that without her father's consent this sweet, trusting, gullible six-year-old is being sent, for weekly instruction, to a Roman Catholic nun. What chance has she?
A human child is shaped by evolution to soak up the culture of her people. Most obviously, she learns the essentials of their language in a matter of months. A large dictionary of words to speak, an encyclopaedia of information to speak about, complicated syntactic and semantic rules to order the speaking, all are transferred from older brains into hers well before she reaches half her adult size. When you are
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? preprogrammed to absorb useful information at a high rate, it is hard to shut out pernicious or damaging information at the same time. With so many mindbytes to be downloaded, so many mental codons to be duplicated, it is no wonder that child brains are gullible, open to almost any suggestion, vulnerable to subversion, easy prey to Moonies, Scientologists and nuns. Like immune-deficient patients, children are wide open to mental infections that adults might brush off without effort.
DNA, too, includes parasitic code. Cellular machinery is extremely good at copying DNA. Where DNA is concerned, it seems to have an eagerness to copy, like a child's eagerness to imitate the language of its parents. Concomitantly, DNA seems eager to be copied. The cell nucleus is a paradise for DNA, humming with sophisticated, fast and accurate duplicating machinery.
Cellular machinery is so friendly towards DNA-duplication that it is small wonder cells play host to DNA parasites - viruses, viroids, plasmids and a riff-raff of other genetic fellow travellers. Parasitic DNA even gets itself spliced seamlessly into the chromosomes themselves. 'Jumping genes' and stretches of 'Selfish DNA' cut or copy themselves out of chromosomes and paste themselves in elsewhere. Deadly oncogenes are almost impossible to distinguish from the legitimate genes between which they are spliced. In evolutionary time, there is probably a continual traffic from 'straight' genes to 'outlaw', and back again. DNA is just DNA. The only thing that distinguishes viral DNA from host DNA is its expected method of passing into future generations. 'Legitimate' host DNA is just DNA that aspires to pass into the next generation via the orthodox route of sperm or egg. 'Outlaw' or parasitic DNA is just DNA that looks to a quicker, less cooperative route to the future, via a sneezed droplet or a smear of blood, rather than via a sperm or egg.
For data on a floppy disk, a computer is a humming paradise just as cell nuclei hum with eagerness to duplicate DNA. Computers and their associated disk and tape readers are designed with high fidelity in mind. As with DNA molecules, magnetized bytes don't literally 'want' to be faithfully copied. Nevertheless, you can write a computer program that takes steps to duplicate itself. Not just duplicate itself within one computer but spread itself to other computers. Computers are so good at copying bytes, and so good at faithfully obeying the instructions contained in those bytes, that they are sitting ducks to self-replicating programs: wide open to subversion by software parasites. Any cynic familiar with the theory of selfish genes and memes would have known
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that modern personal computers, with their promiscuous traffic of floppy disks and email links, were just asking for trouble. The only surprising thing about the current epidemic of computer viruses is that it has been so long in coming.
Computer Viruses: a Model for an Informational Epidemiology
Computer viruses are pieces of code that graft themselves into existing, legitimate programs and subvert the normal actions of those programs. They may travel on exchanged floppy disks, or over networks. They are technically distinguished from 'worms' which are whole programs in their own right, usually travelling over networks. Rather different are 'Trojan horses', a third category of destructive programs, which are not in themselves self-replicating but rely on humans to replicate them because of their pornographic or otherwise appealing content. Both viruses and worms are programs that actually say, in computer language, 'Duplicate Me'. Both may do other things that make their presence felt and perhaps satisfy the hole-in-corner vanity of their authors. These side effects may be 'humorous' (like the virus that makes the Macintosh's built-in loudspeaker enunciate the words 'Don't panic', with predictably opposite effect); malicious (like the viruses that erase the hard disk after a sniggering screen-announcement of the impending disaster); political (the Spanish Telecom and Beijing viruses protest about telephone costs and massacred students respectively); or simply inadvertent (the programmer is incompetent to handle the low-level system calls required to write an effective virus or worm). The famous Internet Worm, which paralysed much of the computing power of the United States on 2 November 1988, was not intended (very) maliciously but got out of control and, within 24 hours, had clogged around 6000 computer memories with exponentially multiplying copies of itself.
Memes now spread around the world at the speed of light, and replicate at rates that make even fruit flies and yeast cells look glacial in comparison. They leap promiscuously from vehicle to vehicle, and from medium to medium, and are proving to be virtually unquarantinable. [Dennett again]
Computer viruses aren't limited to electronic media such as disks and data lines. On its way from one computer to another, a virus may pass through printing ink, light rays in a human lens, optic nerve impulses and finger muscle contractions. A computer fanciers' magazine that printed the text of a virus program for the interest of its readers has been widely condemned. Indeed, such is the appeal of the virus idea to
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? a certain kind of puerile mentality (the masculine gender is used advisedly), that publication of any kind of 'How to' information on designing virus programs is rightly seen as an irresponsible act.
I am not going to publish any virus code. But there are certain tricks of effective virus design that are sufficiently well known, even obvious, that it will do no harm to,mention them, as I need to do in order to develop my theme. They all stem from the virus's need to evade detection while it is spreading.
A virus that clones itself too prolifically within one computer will soon be detected because the symptoms of clogging will become too obvious to ignore. For this reason many virus programs check, before infecting a system, to make sure that they are not already on that system. Incidentally, this opens the way for a defence against viruses that is analogous to immunization. In the days before a specific anti- virus program was available, I myself responded to an early infection of my own hard disk by means of a crude 'vaccination'. Instead of deleting the virus that I had detected, I simply disabled its coded instructions, leaving the 'shell' of the virus with its characteristic external 'signature' intact. In theory, subsequent members of the same virus species that arrived in my system should have recognized the signature of their own kind and refrained from trying to double-infect. I don't know whether this immunization really worked, but in those days it probably was worthwhile 'gutting' a virus and leaving a shell like this, rather than simply removing it lock, stock and barrel. Nowadays it is better to hand the problem over to one of the professionally written anti-virus programs.
A virus that is too virulent will be rapidly detected and scotched. A virus that instantly and catastrophically sabotages every computer in which it finds itself will not find itself in many computers. It may have a most amusing effect on one computer - erase an entire doctoral thesis or something equally side-splitting - but it won't spread as an epidemic. Some viruses, therefore, are designed to have an effect that is small enough to be difficult to detect, but which may nevertheless be extremely damaging. There is one type which, instead of erasing disk sectors wholesale, attacks only spreadsheets, making a few random changes in the (usually financial) quantities entered in the rows and columns. Other viruses evade detection by being triggered probabilistically, for example erasing only one in 16 of the hard disks infected. Yet other viruses employ the time-bomb principle. Most modern computers are 'aware' of the date, and viruses have been triggered to manifest them- selves all around the world, on a particular date such as Friday 13th or
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April Fool's Day. From the parasitic point of view, it doesn't matter how catastrophic the eventual attack is, provided the virus has had plenty of opportunity to spread first (a disturbing analogy to the Medawar/ Williams theory of ageing; we are the victims of lethal and sub-lethal genes that mature only after we have had plenty of time to reproduce). In defence, some large companies go so far as to set aside one 'miner's canary' among theirfleetof computers, and advance its internal calendar a week so that any time-bomb viruses will reveal themselves prematurely before the big day.
Again predictably, the epidemic of computer viruses has triggered an arms race. Antiviral software is doing a roaring trade. These antidote programs - 'Interferon', 'Vaccine', 'Gatekeeper' and others - employ a diverse armoury of tricks. Some are written with specific, known and named, viruses in mind. Others intercept any attempt to meddle with sensitive system areas of memory and warn the user.
The virus principle could in theory be used for non-malicious, even
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beneficial purposes. Harold Thimbleby coins the phrase 'Liveware' for
his already-implemented use of the infection principle for keeping multiple copies of databases up to date. Every time a disk containing the database is plugged into a computer, it looks to see whether there is already another copy present on the local hard disk. If there is, each copy is updated in the light of the other. So, with a bit of luck, it doesn't matter which member of a circle of colleagues enters, say, a new biblio- graphic citation on his personal disk. His newly entered information will readily infect the disks of his colleagues (because the colleagues promiscuously insert their disks into one another's computers) and will spread like an epidemic around the circle. Thimbleby's liveware is not entirely virus-like: it could not spread to just anybody's computer and do damage. It spreads data only to already-existing copies of its own database; and you will not be infected by liveware unless you positively opt for infection.
Incidentally, Thimbleby, who is much concerned with the virus menace, points out that you can gain some protection by using computer systems that other people don't use. The usual justification for purchasing today's numerically dominant personal computer is simply and solely that it is numerically dominant. Almost every knowledgeable person agrees that, in terms of quality and especially user-friendliness, the rival, minority system is superior. Nevertheless, ubiquity is held to be a good in itself, sufficient to outweigh sheer quality. Buy the same (albeit inferior) computer as your colleagues, the argument goes, and you'll be able to benefit from shared software, and from a generally
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? larger circulation of available software. The irony is that, with the advent of the virus plague, 'benefit' is not all that you are likely to get. Not only should we all be very hesitant before we accept a disk from a colleague. We should also be aware that, if we join a large community of users of a particular make of computer, we are also joining a larger community of viruses - even, it turns out, disproportionately larger.
Returning to possible uses of viruses for positive purposes, there are proposals to exploit the 'poacher turned gamekeeper' principle, and 'set a thief to catch a thief. A simple way would be to take any of the existing antiviral programs and load it, as a 'warhead', into a harmless self-replicating virus. From a 'public health' point of view a spreading epidemic of antiviral software could be especially beneficial because the computers most vulnerable to malicious viruses - those whose owners are promiscuous in the exchange of pirated programs - will also be most vulnerable to infection by the healing anti-virus. A more penetrating anti-virus might - as in the immune system - 'learn' or 'evolve' an improved capacity to attack whatever viruses it encountered.
I can imagine other uses of the computer virus principle which, if not exactly altruistic, are at least constructive enough to escape the charge of pure vandalism. A computer company might wish to do market research on the habits of its customers, with a view to improving the design of future products. Do users like to choose files by pictorial icon, or do they opt to display them by textual name only? How deeply do people nest folders (directories) within one another? Do people settle down for a long session with only one program, say a word processor, or are they constantly switching back and forth, say between writing and drawing programs? Do people succeed in moving the mouse pointer straight to the target, or do they meander around in time-wasting hunting movements that could be rectified by a change in design?
The company could send out a questionnaire asking all these questions, but the customers that replied would be a biased sample and, in any case, their own assessment of their computer-using behaviour might be inaccurate. A better solution would be a market research computer program. Customers would be asked to load this program into their system where it would unobtrusively sit, quietly monitoring and tallying key-presses and mouse movements. At the end of a year, the customer would be asked to send in the disk file containing all the tallyings of the market research program. But again, most people would not bother to cooperate and some might see it as an invasion of privacy and of their disk space.
The perfect solution, from the company's point of view, would be a
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virus. Like any other virus it would be self-replicating and secretive. But it would not be destructive or facetious like an ordinary virus. Along with its self-replicating booster, it would contain a market research war- head. The virus would be released surreptitiously into the community of computer users. Just like an ordinary virus it would spread around, as people passed floppy disks and email around the community. As the virus spread from computer to computer, it would build up statistics on user behaviour, monitored secretly from deep within a succession of systems. Every now and again, a copy of the virus would happen to find its way, by normal epidemic traffic, back into one of the company's own computers. There it would be debriefed and its data collated with data from other copies of the virus that had come 'home'.
Looking into the future, it is not fanciful to imagine a time when viruses, both bad and good, have become so ubiquitous that we could speak of an ecological community of viruses and legitimate programs coexisting in the silicosphere. At present, software is advertised as, say, 'Compatible with System 7'. In the future, products may be advertised as 'Compatible with all viruses registered in the 2008 World Virus Census; immune to all listed virulent viruses; takes full advantage of the facilities offered by the following benign viruses if present . . . ' Word- processing software, say, may hand over particular functions, such as word-counting and string-searches, to friendly viruses burrowing autonomously through the text.
Looking even further into the future, whole integrated software systems might grow, not by design, but by something like the growth of an ecological community such as a tropical rainforest. Gangs of mutually compatible viruses might grow up, in the same way as genomes can be regarded as gangs of mutually compatible genes. Indeed, I have even suggested that our genomes should be regarded as gigantic colonies of viruses. Genes cooperate with one another in genomes because natural selection has favoured those genes that prosper in the presence of the other genes that happen to be common in the gene pool. Different gene pools may evolve towards different combinations of mutually com- patible genes. I envisage a time when, in the same kind of way, computer viruses may evolve towards compatibility with other viruses, to form communities or gangs. But then again, perhaps not! At any rate, I find the speculation more alarming than exciting.
At present, computer viruses don't strictly evolve. They are invented by human programmers and if they evolve they do so in the same weak sense as cars or aeroplanes evolve. Designers derive this year's car as a slight modification of last year's car, and they may, more or less
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? consciously, continue a trend of the last few years - further flattening of the radiator grill or whatever it may be. Computer virus designers dream up ever more devious tricks for outwitting the programmers of anti-virus software. But computer viruses don't - so far - mutate and evolve by true natural selection. They may do so in the future. Whether they evolve by natural selection, or whether their evolution is steered by human designers, may not make much difference to their eventual performance. By either kind of evolution, we expect them to become better at concealment, and we expect them to become subtly com- patible with other viruses that are at the same time prospering in the computer community.
DNA viruses and computer viruses spread for the same reason: an environment exists in which there is machinery well set up to duplicate and spread them around and to obey the instructions that the viruses embody. These two environments are, respectively, the environment of cellular physiology and the environment provided by a large community of computers and data-handling machinery. Are there any other environments like these, any other humming paradises of replication?
The Infected Mind
I have already alluded to the programmed-in gullibility of a child, so useful for learning language and traditional wisdom, and so easily subverted by nuns, Moonies and their ilk. More generally, we all exchange information with one another. We don't exactly plug floppy disks into slots in one another's skulls, but we exchange sentences, both through our ears and through our eyes. We notice each other's styles of moving and of dressing, and are influenced. We take in advertising jingles, and are presumably persuaded by them, otherwise hard-headed businessmen would not spend so much money polluting the air with them.
Think about the two qualities that a virus, or any sort of parasitic replicator, demands of a friendly medium: the two qualities that make cellular machinery so friendly towards parasitic DNA, and that make computers so friendly towards computer viruses. These qualities are, first, a readiness to replicate information accurately, perhaps with some mistakes that are subsequently reproduced accurately; and, second, a readiness to obey instructions encoded in the information so replicated. Cellular machinery and electronic computers excel in both these virus- friendly qualities. How do human brains match up? As faithful
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duplicators they are certainly less perfect than either cells or electronic computers. Nevertheless, they are still pretty good, perhaps about as faithful as an RNA virus, though not as good as DNA with all its elaborate proofreading measures against textual degradation. Evidence of the fidelity of brains, especially child brains, as data duplicators, is provided by language itself. Bernard Shaw's Professor Higgins was able by ear alone to place Londoners in the street where they grew up. Fiction is not evidence for anything, but everyone knows that Higgins's fictional skill is only an exaggeration of something we can all do. Any American can tell Deep South from Mid West, New England from Hillbilly. Any New Yorker can tell Bronx from Brooklyn. Equivalent claims could be substantiated for any country. What this phenomenon means is that human brains are capable of pretty accurate copying (otherwise the accents of, say, Newcastle would not be stable enough to be recognized) but with some mistakes (otherwise pronunciation would not evolve, and all speakers of a language would inherit identically the same accents from their remote ancestors). Language evolves, because it has both the great stability and the slight changeability that are prerequisites for any evolving system.
The second requirement of a virus-friendly environment - that it should obey a program of coded instructions - is again only quantitatively less true for brains than for cells or computers. We sometimes obey orders from one another, but also we sometimes don't. Nevertheless, it is a telling fact that, the world over, the vast majority of children follow the religion of their parents rather than any of the other available religions. Instructions to genuflect, to bow towards Mecca, to nod one's head rhythmically towards the wall, to shake like a maniac, to 'speak in tongues' - the list of such arbitrary and pointless motor patterns offered by religion alone is extensive - are obeyed, if not slavishly, at least with some reasonably high statistical probability.
Less portentously, and again especially prominent in children, the 'craze' is a striking example of behaviour that owes more to epi- demiology than to rational choice. Yoyos, hula hoops and pogo sticks, with their associated behavioural fixed actions, sweep through schools, and more sporadically leap from school to school, in patterns that differ from a measles epidemic in no serious particular. Ten years ago, you could have travelled thousands of miles through the United States and never seen a baseball cap turned back to front. Today the reverse base- ball cap is ubiquitous. I do not know what the pattern of geographic spread of the reverse baseball cap precisely was, but epidemiology is certainly among the professions primarily qualified to study it. We
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? don't have to get into arguments about 'determinism'; we don't have to claim that children are compelled to imitate their fellows' hat fashions. It is enough that their hat-wearing behaviour, as a matter of fact, is statistically affected by the hat-wearing behaviour of their fellows.
Trivial though they are, crazes provide us with yet more circum- stantial evidence that human minds, especially perhaps juvenile ones, have the qualities that we have singled out as desirable for an informa- tional parasite. At the very least the mind is a plausible candidate for infection by something like a computer virus, even if it is not quite such a parasite's dream-environment as a cell nucleus or an electronic computer. It is intriguing to wonder what it might feel like, from the inside, if one's mind were the victim of a 'virus'. This might be a deliberately designed parasite, like a present-day computer virus. Or it might be an inadvertently mutated and unconsciously evolved parasite. Either way, especially if the evolved parasite was the memetic descendant of a long line of successful ancestors, we are entitled to expect the typical 'mind virus' to be pretty good at its job of getting itself successfully replicated.
Progressive evolution of more effective mind-parasites will have two aspects. New 'mutants' (either random or designed by humans) that are better at spreading will become more numerous. And there will be a ganging up of ideas that flourish in one another's presence, ideas that mutually support one another just as genes do and, as I have speculated, computer viruses may one day do. We expect that replicators will go around together from brain to brain in mutually compatible gangs. These gangs will come to constitute a package, which may be sufficiently stable to deserve a collective name such as Roman Catholicism or Voodoo. It doesn't too much matter whether we analogize the whole package to a single virus, or each one of the component parts to a single virus. The analogy is not that precise anyway, just as the distinction between a computer virus and a computer worm is nothing to get worked up about. What matters is that minds are friendly environ- ments to parasitic, self-replicating ideas or information, and that minds are typically massively infected.
Like computer viruses, successful mind viruses will tend to be hard for their victims to detect. If you are the victim of one, the chances are that you won't know it, and may even vigorously deny it. Accepting that a virus might be difficult to detect in your own mind, what tell-tale signs might you look out for? I shall answer by imagining how a medical textbook might describe the typical symptoms of a sufferer (arbitrarily assumed to be male).
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1. The patient typically finds himself impelled by some deep, inner conviction that something is true, or right, or virtuous: a conviction that doesn't seem to owe anything to evidence or reason, but which, nevertheless, he feels as totally compelling and convincing. We doctors refer to such a belief as 'faith'.
2. Patients typically make a positive virtue of faith's being strong and unshakeable, in spite of not being based upon evidence. Indeed, they may feel that the less evidence there is, the more virtuous the belief (see below).
Years later, when I became a tutor myself, I taught a young woman who affected an unusual habit. When asked a question which required deep thought, she would screw her eyes tight shut, jerk her head down to her chest and then freeze for up to half a minute before looking up, opening her eyes, and answering the question with fluency and intelligence. I was amused by this, and did an imitation of it to divert my colleagues after dinner. Among them was a distinguished Oxford philosopher. As soon as he saw my imitation, he immediately said: 'That's Wittgenstein! Is her surname by any chance? ' Taken aback, I said that it was. T thought so,' said my colleague. 'Both her parents are devoted followers of Wittgenstein. ' The gesture had passed from the great philosopher, via one or both of her parents, to my pupil. I suppose that, although my further imitation was done in jest, I must count myself a fourth generation transmitter of the gesture. And who knows where Wittgenstein got it?
Imitation is how a child learns its particular language rather than some other language. It is why people speak more like their own parents than like other people's parents. It is why regional accents, and on a longer timescale separate languages, exist. It is why religions persist along family lines rather than being chosen afresh in every generation. There is at least a superficial analogy to the longitudinal transmission of genes down generations, and to the horizontal transmission of genes in
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viruses. Without prejudging the issue of whether the analogy is a fruitful one, if we want even to talk about it we had better have a name for the entity that might play the role of gene in the transmission of words, ideas, faiths, mannerisms and fashions. Since 1976, when the word was coined, increasing numbers of people have adopted the name 'meme' for the postulated gene analogue.
The compilers of the Oxford English Dictionaries operate a sensible criterion for deciding whether a new word shall be canonized by inclusion. The aspirant word must be commonly used without needing to be denned and without its coining being attributed. To ask the metamemetic question, how widespread is 'meme', a far from ideal, but nevertheless convenient method of sampling the meme pool, is provided by the World Wide Web. I did a quick search of the web on the day of writing this, which happened to be 29 August 1998. 'Meme' is mentioned about half a million times, but that's a ridiculously high figure, obviously confounded by various acronyms and the French meme. The adjectival form 'memetic' is genuinely exclusive, and it clocked up 5042 mentions. To put this number into perspective, I compared a few other recently coined words or fashionable expressions. Spin doctor (or spin-doctor) gets 1412 mentions, dumbing down 3905, docudrama (or docu-drama) 2848, sociobiology 6679, catastrophe theory 1472, edge of chaos 2673, wannabee 2650, zippergate 1752, studmuffin 776, post-structural (or poststructural) 577, extended phenotype 515, exaptation 307. Of the 5042 mentions of memetic, more than 90 per cent make no mention of the origin of the word, which suggests that it does indeed meet the OED's criterion. And the Oxford Dictionary now does contain the following definition: meme: 'a self-replicating element of culture, passed on by imitation. '
Further searching of the internet reveals a newsgroup talking-shop, 'alt. memetics', which has received about 12,000 postings during the past year. There are on-line articles on, among many other things, 'The New Meme', 'Meme, Counter-meme', 'Memetics: a Systems Metabiology', 'Memes, and Grinning Idiot Press', 'Memes, Metamemes and Polities', 'Cryonics, religions and memes', 'Selfish Memes and the evolution of cooperation', and 'Running down the Meme'. There are separate web pages on 'Memetics', 'Memes', 'The C Memetic Nexus', 'Meme theorists on the web', 'Meme of the week', 'Meme Central', 'Arkuat's Meme Workshop', 'Some pointers and a short introduction to memetics', 'Memetics Index' and 'Meme Gardening Page'. There is even a new religion (tongue in cheek, I think), called the 'Church of Virus', complete with its own list of Sins and Virtues, and its own patron saint (Saint
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? Charles Darwin, canonized as 'perhaps the most influential memetic engineer of the modern era') and I was alarmed to discover a passing reference to 'Saint Dawkins'.
Memes travel longitudinally down generations, but they travel hori- zontally too, like viruses in an epidemic. Indeed, it is largely horizontal epidemiology that we are studying when we measure the spread of a word like memetic, docudrama or studmuffin over the internet. Crazes among schoolchildren provide particularly tidy examples. When I was about nine, my father taught me to fold a square of paper to make an origami Chinese junk. It was a remarkable feat of artificial embryology, passing through a distinctive series of intermediate stages: catamaran with two hulls, cupboard with doors, picture in a frame, and finally the junk itself, fully seaworthy or at least bathworthy, complete with deep hold, and two flat decks each surmounted by a large, square-rigged sail. The point of the story is that I went back to school and infected my friends with the skill, and it then spread around the school with the speed of the measles and pretty much the same epidemiological time- course. I don't know whether the epidemic subsequently jumped to other schools (a boarding school is a somewhat isolated backwater of the meme pool). But I do know that my father himself originally picked up the Chinese Junk meme during an almost identical epidemic at the same school 25 years earlier. The earlier virus was launched by the school matron. Long after the old matron's departure, I had reintroduced her meme to a new cohort of small boys.
Before leaving the Chinese junk, let me use it to make one more point. A favourite objection to the meme/gene analogy is that memes, if they exist at all, are transmitted with too low fidelity to perform a gene-like role in any realistically Darwinian selection process. The difference between high fidelity genes and low fidelity memes is assumed to follow from the fact that genes, but not memes, are digital. I am sure that the details of Wittgenstein's mannerism were far from faithfully reproduced when I imitated my pupil's imitation of her parents' imitation of Wittgenstein. The form and timing of the tic undoubtedly mutated over the generations, as in the childhood game of Chinese Whispers (Americans call it Telephone).
Suppose we assemble a line of children. A picture of, say, a Chinese junk is shown to the first child, who is asked to draw it. The drawing, but not the original picture, is then shown to the second child, who is asked to make her own drawing of it. The second child's drawing is shown to the third child, who draws it again, and so the series proceeds until the twentieth child, whose drawing is revealed to everyone and
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compared with the first. Without even doing the experiment, we know what the result will be. The twentieth drawing will be so unlike the first as to be unrecognizable. Presumably, if we lay the drawings out in order, we shall notice some resemblance between each one and its immediate predecessor and successor, but the mutation rate will be so high as to destroy all semblance after a few generations. A trend will be visible as we walk from one end of the series of drawings to the other, and the direction of the trend will be degeneration. Evolutionary geneticists have long understood that natural selection cannot work unless the mutation rate is low. Indeed, the initial problem of overcoming the fidelity barrier has been described as the Catch-22 of the Origin of Life. Darwinism depends upon high fidelity gene replication. How then can the meme, with its apparently dismal lack of fidelity, serve as quasi-gene in any quasi-Darwinian process?
It isn't always as dismal as you think, and high fidelity is not necessarily synonymous with digital. Suppose we set up our Chinese Whispers game again, but this time with a crucial difference. Instead of asking the first child to copy a drawing of a junk, we teach her, by demonstration, to make an origami model of a junk. When she has mastered the skill and made her own junk, the first child is asked to turn round to the second child and teach him how to make one. So the skill passes down the line to the twentieth child. What will be the result of this experiment? What will the twentieth child produce, and what shall we observe if we lay the 20 efforts out in order along the ground? I haven't done it, but I will make the following confident prediction, assuming that we run the experiment many times on different groups of 20 children. In several of the experiments, a child somewhere along the line will forget some crucial step in the skill taught him by the previous child, and the line of phenotypes will suffer an abrupt macro- mutation which will presumably then be copied to the end of the line, or until another discrete mistake is made. The end result of such mutated lines will not bear any resemblance to a Chinese junk at all. But in a good number of experiments the skill will correctly pass all along the line, and the twentieth junk will be no worse and no better, on average, than the first junk. If we then lay the 20 junks out in order, some will be more perfect than others, but imperfections will not be copied on down the line. If the fifth child is hamfisted and makes a clumsily asymmetrical or floppy junk, his quantitative errors will be corrected if the sixth child happens to be more dexterous. The 20 junks will not exhibit a progressive deterioration in the way that the 20 drawings of our first experiment undoubtedly would.
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? Why? What is the crucial difference between the two kinds of experi- ment? It is this. Inheritance in the drawing experiment is Lamarckian (Susan Blackmore calls it 'copying the product'). In the origami experiment it is Weismannian (Blackmore's 'copying the instructions'). In the drawing experiment, the phenotype in every generation is also the genotype - it is what is passed on to the next generation. In the origami experiment, what passes to the next generation is not the paper phenotype but a set of instructions for making it. Imperfections in the execution of the instructions result in imperfect junks (phenotypes) but they are not passed on to future generations: they are non-memetic. Here are the first five instructions in the Weismannian meme-line of instructions for making a Chinese junk:
1. Take a square sheet of paper and fold all four corners exactly into the middle.
2. Take the reduced square so formed, and fold one side into the middle.
3. Fold the opposite side into the middle, symmetrically.
4. In the same way, take the rectangle so formed, and fold its two ends
into the middle.
5. Take the small square so formed, and fold it backwards, exactly
along the straight line where your last two folds met.
. . . And so on, through 20 or 30 instructions of this kind. These instruc- tions, though I would not wish to call them digital, are potentially of very high fidelity, just as if they were digital. This is because they all make reference to idealized tasks like 'fold the four corners exactly into the middle'. If the paper is not exactly square, or if a child folds ineptly so that, say, the first corner overshoots the middle and the fourth corner undershoots it, the junk that results will be inelegant. But the next child in the line will not copy the error, for she will assume that her instructor intended to fold all four corners into the exact centre of a perfect square. The instructions are self-normalizing. The code is error- correcting.
The instructions are more effectively passed on if verbally reinforced, but they can be transmitted by demonstration alone. A Japanese child could teach an English one, though neither has a word of the other's language. In the same way, a Japanese master carpenter could convey his skills to an equally monoglot English apprentice. The apprentice would not copy obvious mistakes. If the master hit his thumb with a hammer, the apprentice would correctly guess, even without
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understanding the Japanese for '** **** **! ', that he meant to hit the nail. He would not make a Lamarckian copy of the precise details of every hammer blow, but copy instead the inferred instruction: drive the nail in with as many blows of your hammer as it takes your arm to achieve the same idealized end result as the master has achieved with his - a nail-head flush with the wood.
I believe that these considerations greatly reduce, and probably remove altogether, the objection that memes are copied with insufficient fidelity to be compared with genes. For me, the quasi-genetic inheritance of language, and of religious and traditional customs, teaches the same lesson. Another objection is that we don't know what memes are made of or where they reside. Memes have not yet found their Watson and Crick; they even lack their Mendel. Whereas genes are to be found in precise locations on chromosomes, memes presumably exist in brains, and we have even less chance of seeing one than of seeing a gene (though the neurobiologist Juan Delius has pictured his conjecture of
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whatamememightlooklike ). Aswithgenes,wetrackmemesthrough
populations by their phenotypes. The 'phenotype' of the Chinese junk meme is made of paper. With the exception of 'extended phenotypes' such as beaver dams and caddis larva houses, the phenotypes of genes are normally parts of living bodies. Meme phenotypes seldom are.
But it can happen. To return to my school again, a Martian geneticist, visiting the school during the morning cold bath ritual, would have unhesitatingly diagnosed an 'obvious' genetic polymorphism. About 50 per cent of the boys were circumcised and 50 per cent were not. The boys, incidentally, were highly conscious of the polymorphism and we classified ourselves into Roundheads versus Cavaliers (I have recently read of another school in which the boys even organized themselves into two football teams along the same lines). It is, of course, not a genetic but a memetic polymorphism. But the Martian's mistake is completely understandable; the morphological discontinuity is of exactly the kind that one normally expects to find produced by genes.
In England at the time, infant circumcision was a medical whim, and the roundhead/cavalier polymorphism at my school probably owed less to longitudinal transmission than to differing fashions in the various hospitals where we happened to have been born - horizontal memetic transmission yet again. But through most of history circumcision has been longitudinally transmitted as a badge of religion (ofparents' religion I hasten to point out, for the unfortunate child is normally too young to know his own religious mind). Where circumcision is religiously or traditionally based (the barbaric custom of female 'circumcision'
? always is), the transmission will follow a longitudinal pattern of heredity, very similar to the pattern for true genetic transmission, and often persisting for many generations. Our Martian geneticist would have to work quite hard to discover that no genes are involved in the genesis of the roundhead phenotype.
The Martian geneticist's eyes would also pop out on stalks (assuming they weren't on stalks to begin with) at the contemplation of certain styles of clothing and hairdressing, and their inheritance patterns. The black skullcapped phenotype shows a marked tendency towards longi- tudinal transmission from father to son (or it may be from maternal grandfather to grandson), and there is clear linkage to the rarer pigtail- plaited sideburn phenotype. Behavioural phenotypes such as genuflecting in front of crosses, and facing east to kneel five times per day, are inherited longitudinally too, and are in strong linkage disequilibrium with the previously mentioned phenotypes, as is the red-dot-on- forehead phenotype, and the saffron robes/shaven head linkage group.
Genes are accurately copied and transmitted from body to body, but some are transmitted at greater frequency than others - by definition they are more successful. This is natural selection, and it is the explana- tion for most of what is interesting and remarkable about life. But is there a similar meme-based natural selection? Perhaps we can use the internet again to investigate natural selection among memes? As it happens, around the time the word meme was coined (actually a little
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later), a rival synonym, 'culturgen', was proposed. Today, culturgen is
mentioned 20 times on the World Wide Web, compared with meme's 5042. Moreover, of those 20, 17 also mention the source of the word, falling foul of the Oxford Dictionary's criterion. Perhaps it is not too fanciful to imagine a Darwinian struggle between the two memes (or culturgens), and it is not totally silly to ask why one of them was so much more successful. Perhaps it is because meme is a monosyllable similar to gene, which therefore lends itself to quasi-genetic sub- coinings: meme pool (352), memotype (58), memeticist (163), memeoid (or memoid) (28), retromeme (14), population memetics (41), meme complex (494), memetic engineering (302) and metameme (71) are all listed in a 'Memetic Lexicon' on the World Wide Web (the numbers in brackets count the mentions of each word on the World Wide Web on my sampling day). Culturgen-based equivalents would be less snappy. Or the success of meme against culturgen may have been initially just a non-Darwinian matter of chance - memetic drift (85) - followed by a self-reinforcing positive feedback effect ('unto every one that hath shall be given, and he shall have abundance: but from him
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that hath not shall be taken away even that which he hath' (Matthew 25:29).
I have mentioned two favourite objections to the meme idea: memes have insufficient copying fidelity, and nobody really knows what a meme physically is. A third is the vexed question of how large a unit deserves the name meme. Is the whole Roman Catholic Church one meme, or should we use the word for one constituent unit, such as the idea of incense or the transubstantiation? Or for something in between? The answer is to be found in the concept of the meme-complex or 'memeplex'.
Memes, like genes, are selected against the background of other memes in the meme pool. The result is that gangs of mutually compatible memes - coadapted meme complexes or memeplexes - are found cohabiting in individual brains. This is not because selection has chosen them as a group, but because each separate member of the group tends to be favoured when its environment happens to be dominated by the others. An exactly similar point can be made about genetic selection. Every gene in a gene pool constitutes part of the environmental background against which the other genes are naturally selected, so it's no wonder natural selection favours genes that 'cooperate' in building those highly integrated and unified machines called organisms. By analogy with coadapted gene complexes, memes, selected against the background of each other, 'cooperate' in mutually supportive memeplexes - supportive within the memeplex but hostile to rival memeplexes. Religions may be the most convincing examples of memeplexes, but they are by no means the only ones.
I am occasionally accused of having backtracked on memes; of having lost heart, pulled in my horns, had second thoughts. The truth is that my first thoughts were more modest than some memeticists might have wished. For me, the original mission of the meme was negative. The word was introduced at the end of a book which other- wise must have seemed entirely devoted to extolling the selfish gene as the be-all and end-all of evolution, the fundamental unit of selection, the entity in the hierarchy of life which all adaptations could be said to benefit. There was a risk that my readers would misunderstand the message as being necessarily about genes in the sense of DNA molecules. On the contrary, DNA was incidental. The real unit of natural selection was any kind of replicator, any unit of which copies are made, with occasional errors, and with some influence or power over their own probability of replication. The genetic natural selection identified by neo-Darwinism as the driving force of evolution on this planet was only
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? a special case of a more general process that I came to dub 'Universal Darwinism'. Perhaps we'd have to go to other planets in order to discover any other examples. But maybe we didn't have to go that far. Could it be that a new kind of Darwinian replicator was even now staring us in the face? This was where the meme came in.
I would have been content, then, if the meme had done its work of simply persuading my readers that the gene was only a special case: that its role in the play of Universal Darwinism could be filled by any entity in the universe answering to the definition of Replicator. The original didactic purpose of the meme was the negative one of cutting the selfish gene down to size. I became a little alarmed at the number of my readers who took the meme more positively as a theory of human culture in its own right - either to criticize it (unfairly, given my original modest intention) or to carry it far beyond the limits of what I then thought justified. This was why I may have seemed to backtrack.
But I was always open to the possibility that the meme might one day be developed into a proper hypothesis of the human mind, and I did not know how ambitious such a thesis might turn out to be. I am delighted that others are now undertaking it. *
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*In addition to Susan Blackmore's The Meme Machine, other books that make heavy use of the meme idea are R. Brodie, Virus of the Mind: the New Science of the Meme (Seattle, Integral Press, 1996) (not to be confused with my essay (see over page), which was published three years earlier); A. Lynch, Thought Contagion: How Belief Spreads Through Society (New York, Basic Books, 1998); J. M. Balkin, Cultural Software (New Haven, Yale University Press, 1998); H. Bloom, The Lucifer Principle (Sydney, Allen & Unwin, 1995); Robert Aunger, The Electric Meme (New York, Simon & Schuster, 2002); Kevin Laland and Gillian Brown, Sense and Nonsense (Oxford, Oxford University Press, 2002); and Stephen Shennan, Genes, Memes and Human History (London, Thames and Hudson, 2002). A turning point in the fortunes of the meme was its adoption and development by Daniel Dennett as a cornerstone of his theory of the evolution of the mind, especially in his two books Consciousness Explained (Boston, Little Brown, 1991) and Darwin's Dangerous Idea (New York, Simon & Schuster, 1995).
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The haven all memes depend on reaching is the human mind, but a human mind is itself an artifact created when memes restructure a human brain in order to make it a better habitat for memes. The avenues for entry and departure are modified to suit local conditions, and strengthened by various artificial devices that enhance fidelity and prolixity of replication: native Chinese minds differ dramatically from native French minds, and literate minds differ from illiterate minds. What memes provide in return to the organisms in which they reside is an incalculable store of advantages - with some Trojan horses thrown in for good measure . . .
78 Daniel Dennett
Duplication-Fodder
A beautiful child close to me, six and the apple of her father's eye, believes that Thomas the Tank Engine really exists. She believes in Father Christmas, and when she grows up her ambition is to be a tooth fairy. She and her schoolfriends believe the solemn word of respected adults that tooth fairies and Father Christmas really exist. This little girl is of an age to believe whatever you tell her.
If you tell her about witches changing princes into frogs, she will believe you. If you tell her that bad children roast forever in hell, she will have nightmares. I have just discovered that without her father's consent this sweet, trusting, gullible six-year-old is being sent, for weekly instruction, to a Roman Catholic nun. What chance has she?
A human child is shaped by evolution to soak up the culture of her people. Most obviously, she learns the essentials of their language in a matter of months. A large dictionary of words to speak, an encyclopaedia of information to speak about, complicated syntactic and semantic rules to order the speaking, all are transferred from older brains into hers well before she reaches half her adult size. When you are
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? preprogrammed to absorb useful information at a high rate, it is hard to shut out pernicious or damaging information at the same time. With so many mindbytes to be downloaded, so many mental codons to be duplicated, it is no wonder that child brains are gullible, open to almost any suggestion, vulnerable to subversion, easy prey to Moonies, Scientologists and nuns. Like immune-deficient patients, children are wide open to mental infections that adults might brush off without effort.
DNA, too, includes parasitic code. Cellular machinery is extremely good at copying DNA. Where DNA is concerned, it seems to have an eagerness to copy, like a child's eagerness to imitate the language of its parents. Concomitantly, DNA seems eager to be copied. The cell nucleus is a paradise for DNA, humming with sophisticated, fast and accurate duplicating machinery.
Cellular machinery is so friendly towards DNA-duplication that it is small wonder cells play host to DNA parasites - viruses, viroids, plasmids and a riff-raff of other genetic fellow travellers. Parasitic DNA even gets itself spliced seamlessly into the chromosomes themselves. 'Jumping genes' and stretches of 'Selfish DNA' cut or copy themselves out of chromosomes and paste themselves in elsewhere. Deadly oncogenes are almost impossible to distinguish from the legitimate genes between which they are spliced. In evolutionary time, there is probably a continual traffic from 'straight' genes to 'outlaw', and back again. DNA is just DNA. The only thing that distinguishes viral DNA from host DNA is its expected method of passing into future generations. 'Legitimate' host DNA is just DNA that aspires to pass into the next generation via the orthodox route of sperm or egg. 'Outlaw' or parasitic DNA is just DNA that looks to a quicker, less cooperative route to the future, via a sneezed droplet or a smear of blood, rather than via a sperm or egg.
For data on a floppy disk, a computer is a humming paradise just as cell nuclei hum with eagerness to duplicate DNA. Computers and their associated disk and tape readers are designed with high fidelity in mind. As with DNA molecules, magnetized bytes don't literally 'want' to be faithfully copied. Nevertheless, you can write a computer program that takes steps to duplicate itself. Not just duplicate itself within one computer but spread itself to other computers. Computers are so good at copying bytes, and so good at faithfully obeying the instructions contained in those bytes, that they are sitting ducks to self-replicating programs: wide open to subversion by software parasites. Any cynic familiar with the theory of selfish genes and memes would have known
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that modern personal computers, with their promiscuous traffic of floppy disks and email links, were just asking for trouble. The only surprising thing about the current epidemic of computer viruses is that it has been so long in coming.
Computer Viruses: a Model for an Informational Epidemiology
Computer viruses are pieces of code that graft themselves into existing, legitimate programs and subvert the normal actions of those programs. They may travel on exchanged floppy disks, or over networks. They are technically distinguished from 'worms' which are whole programs in their own right, usually travelling over networks. Rather different are 'Trojan horses', a third category of destructive programs, which are not in themselves self-replicating but rely on humans to replicate them because of their pornographic or otherwise appealing content. Both viruses and worms are programs that actually say, in computer language, 'Duplicate Me'. Both may do other things that make their presence felt and perhaps satisfy the hole-in-corner vanity of their authors. These side effects may be 'humorous' (like the virus that makes the Macintosh's built-in loudspeaker enunciate the words 'Don't panic', with predictably opposite effect); malicious (like the viruses that erase the hard disk after a sniggering screen-announcement of the impending disaster); political (the Spanish Telecom and Beijing viruses protest about telephone costs and massacred students respectively); or simply inadvertent (the programmer is incompetent to handle the low-level system calls required to write an effective virus or worm). The famous Internet Worm, which paralysed much of the computing power of the United States on 2 November 1988, was not intended (very) maliciously but got out of control and, within 24 hours, had clogged around 6000 computer memories with exponentially multiplying copies of itself.
Memes now spread around the world at the speed of light, and replicate at rates that make even fruit flies and yeast cells look glacial in comparison. They leap promiscuously from vehicle to vehicle, and from medium to medium, and are proving to be virtually unquarantinable. [Dennett again]
Computer viruses aren't limited to electronic media such as disks and data lines. On its way from one computer to another, a virus may pass through printing ink, light rays in a human lens, optic nerve impulses and finger muscle contractions. A computer fanciers' magazine that printed the text of a virus program for the interest of its readers has been widely condemned. Indeed, such is the appeal of the virus idea to
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? a certain kind of puerile mentality (the masculine gender is used advisedly), that publication of any kind of 'How to' information on designing virus programs is rightly seen as an irresponsible act.
I am not going to publish any virus code. But there are certain tricks of effective virus design that are sufficiently well known, even obvious, that it will do no harm to,mention them, as I need to do in order to develop my theme. They all stem from the virus's need to evade detection while it is spreading.
A virus that clones itself too prolifically within one computer will soon be detected because the symptoms of clogging will become too obvious to ignore. For this reason many virus programs check, before infecting a system, to make sure that they are not already on that system. Incidentally, this opens the way for a defence against viruses that is analogous to immunization. In the days before a specific anti- virus program was available, I myself responded to an early infection of my own hard disk by means of a crude 'vaccination'. Instead of deleting the virus that I had detected, I simply disabled its coded instructions, leaving the 'shell' of the virus with its characteristic external 'signature' intact. In theory, subsequent members of the same virus species that arrived in my system should have recognized the signature of their own kind and refrained from trying to double-infect. I don't know whether this immunization really worked, but in those days it probably was worthwhile 'gutting' a virus and leaving a shell like this, rather than simply removing it lock, stock and barrel. Nowadays it is better to hand the problem over to one of the professionally written anti-virus programs.
A virus that is too virulent will be rapidly detected and scotched. A virus that instantly and catastrophically sabotages every computer in which it finds itself will not find itself in many computers. It may have a most amusing effect on one computer - erase an entire doctoral thesis or something equally side-splitting - but it won't spread as an epidemic. Some viruses, therefore, are designed to have an effect that is small enough to be difficult to detect, but which may nevertheless be extremely damaging. There is one type which, instead of erasing disk sectors wholesale, attacks only spreadsheets, making a few random changes in the (usually financial) quantities entered in the rows and columns. Other viruses evade detection by being triggered probabilistically, for example erasing only one in 16 of the hard disks infected. Yet other viruses employ the time-bomb principle. Most modern computers are 'aware' of the date, and viruses have been triggered to manifest them- selves all around the world, on a particular date such as Friday 13th or
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April Fool's Day. From the parasitic point of view, it doesn't matter how catastrophic the eventual attack is, provided the virus has had plenty of opportunity to spread first (a disturbing analogy to the Medawar/ Williams theory of ageing; we are the victims of lethal and sub-lethal genes that mature only after we have had plenty of time to reproduce). In defence, some large companies go so far as to set aside one 'miner's canary' among theirfleetof computers, and advance its internal calendar a week so that any time-bomb viruses will reveal themselves prematurely before the big day.
Again predictably, the epidemic of computer viruses has triggered an arms race. Antiviral software is doing a roaring trade. These antidote programs - 'Interferon', 'Vaccine', 'Gatekeeper' and others - employ a diverse armoury of tricks. Some are written with specific, known and named, viruses in mind. Others intercept any attempt to meddle with sensitive system areas of memory and warn the user.
The virus principle could in theory be used for non-malicious, even
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beneficial purposes. Harold Thimbleby coins the phrase 'Liveware' for
his already-implemented use of the infection principle for keeping multiple copies of databases up to date. Every time a disk containing the database is plugged into a computer, it looks to see whether there is already another copy present on the local hard disk. If there is, each copy is updated in the light of the other. So, with a bit of luck, it doesn't matter which member of a circle of colleagues enters, say, a new biblio- graphic citation on his personal disk. His newly entered information will readily infect the disks of his colleagues (because the colleagues promiscuously insert their disks into one another's computers) and will spread like an epidemic around the circle. Thimbleby's liveware is not entirely virus-like: it could not spread to just anybody's computer and do damage. It spreads data only to already-existing copies of its own database; and you will not be infected by liveware unless you positively opt for infection.
Incidentally, Thimbleby, who is much concerned with the virus menace, points out that you can gain some protection by using computer systems that other people don't use. The usual justification for purchasing today's numerically dominant personal computer is simply and solely that it is numerically dominant. Almost every knowledgeable person agrees that, in terms of quality and especially user-friendliness, the rival, minority system is superior. Nevertheless, ubiquity is held to be a good in itself, sufficient to outweigh sheer quality. Buy the same (albeit inferior) computer as your colleagues, the argument goes, and you'll be able to benefit from shared software, and from a generally
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? larger circulation of available software. The irony is that, with the advent of the virus plague, 'benefit' is not all that you are likely to get. Not only should we all be very hesitant before we accept a disk from a colleague. We should also be aware that, if we join a large community of users of a particular make of computer, we are also joining a larger community of viruses - even, it turns out, disproportionately larger.
Returning to possible uses of viruses for positive purposes, there are proposals to exploit the 'poacher turned gamekeeper' principle, and 'set a thief to catch a thief. A simple way would be to take any of the existing antiviral programs and load it, as a 'warhead', into a harmless self-replicating virus. From a 'public health' point of view a spreading epidemic of antiviral software could be especially beneficial because the computers most vulnerable to malicious viruses - those whose owners are promiscuous in the exchange of pirated programs - will also be most vulnerable to infection by the healing anti-virus. A more penetrating anti-virus might - as in the immune system - 'learn' or 'evolve' an improved capacity to attack whatever viruses it encountered.
I can imagine other uses of the computer virus principle which, if not exactly altruistic, are at least constructive enough to escape the charge of pure vandalism. A computer company might wish to do market research on the habits of its customers, with a view to improving the design of future products. Do users like to choose files by pictorial icon, or do they opt to display them by textual name only? How deeply do people nest folders (directories) within one another? Do people settle down for a long session with only one program, say a word processor, or are they constantly switching back and forth, say between writing and drawing programs? Do people succeed in moving the mouse pointer straight to the target, or do they meander around in time-wasting hunting movements that could be rectified by a change in design?
The company could send out a questionnaire asking all these questions, but the customers that replied would be a biased sample and, in any case, their own assessment of their computer-using behaviour might be inaccurate. A better solution would be a market research computer program. Customers would be asked to load this program into their system where it would unobtrusively sit, quietly monitoring and tallying key-presses and mouse movements. At the end of a year, the customer would be asked to send in the disk file containing all the tallyings of the market research program. But again, most people would not bother to cooperate and some might see it as an invasion of privacy and of their disk space.
The perfect solution, from the company's point of view, would be a
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virus. Like any other virus it would be self-replicating and secretive. But it would not be destructive or facetious like an ordinary virus. Along with its self-replicating booster, it would contain a market research war- head. The virus would be released surreptitiously into the community of computer users. Just like an ordinary virus it would spread around, as people passed floppy disks and email around the community. As the virus spread from computer to computer, it would build up statistics on user behaviour, monitored secretly from deep within a succession of systems. Every now and again, a copy of the virus would happen to find its way, by normal epidemic traffic, back into one of the company's own computers. There it would be debriefed and its data collated with data from other copies of the virus that had come 'home'.
Looking into the future, it is not fanciful to imagine a time when viruses, both bad and good, have become so ubiquitous that we could speak of an ecological community of viruses and legitimate programs coexisting in the silicosphere. At present, software is advertised as, say, 'Compatible with System 7'. In the future, products may be advertised as 'Compatible with all viruses registered in the 2008 World Virus Census; immune to all listed virulent viruses; takes full advantage of the facilities offered by the following benign viruses if present . . . ' Word- processing software, say, may hand over particular functions, such as word-counting and string-searches, to friendly viruses burrowing autonomously through the text.
Looking even further into the future, whole integrated software systems might grow, not by design, but by something like the growth of an ecological community such as a tropical rainforest. Gangs of mutually compatible viruses might grow up, in the same way as genomes can be regarded as gangs of mutually compatible genes. Indeed, I have even suggested that our genomes should be regarded as gigantic colonies of viruses. Genes cooperate with one another in genomes because natural selection has favoured those genes that prosper in the presence of the other genes that happen to be common in the gene pool. Different gene pools may evolve towards different combinations of mutually com- patible genes. I envisage a time when, in the same kind of way, computer viruses may evolve towards compatibility with other viruses, to form communities or gangs. But then again, perhaps not! At any rate, I find the speculation more alarming than exciting.
At present, computer viruses don't strictly evolve. They are invented by human programmers and if they evolve they do so in the same weak sense as cars or aeroplanes evolve. Designers derive this year's car as a slight modification of last year's car, and they may, more or less
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? consciously, continue a trend of the last few years - further flattening of the radiator grill or whatever it may be. Computer virus designers dream up ever more devious tricks for outwitting the programmers of anti-virus software. But computer viruses don't - so far - mutate and evolve by true natural selection. They may do so in the future. Whether they evolve by natural selection, or whether their evolution is steered by human designers, may not make much difference to their eventual performance. By either kind of evolution, we expect them to become better at concealment, and we expect them to become subtly com- patible with other viruses that are at the same time prospering in the computer community.
DNA viruses and computer viruses spread for the same reason: an environment exists in which there is machinery well set up to duplicate and spread them around and to obey the instructions that the viruses embody. These two environments are, respectively, the environment of cellular physiology and the environment provided by a large community of computers and data-handling machinery. Are there any other environments like these, any other humming paradises of replication?
The Infected Mind
I have already alluded to the programmed-in gullibility of a child, so useful for learning language and traditional wisdom, and so easily subverted by nuns, Moonies and their ilk. More generally, we all exchange information with one another. We don't exactly plug floppy disks into slots in one another's skulls, but we exchange sentences, both through our ears and through our eyes. We notice each other's styles of moving and of dressing, and are influenced. We take in advertising jingles, and are presumably persuaded by them, otherwise hard-headed businessmen would not spend so much money polluting the air with them.
Think about the two qualities that a virus, or any sort of parasitic replicator, demands of a friendly medium: the two qualities that make cellular machinery so friendly towards parasitic DNA, and that make computers so friendly towards computer viruses. These qualities are, first, a readiness to replicate information accurately, perhaps with some mistakes that are subsequently reproduced accurately; and, second, a readiness to obey instructions encoded in the information so replicated. Cellular machinery and electronic computers excel in both these virus- friendly qualities. How do human brains match up? As faithful
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duplicators they are certainly less perfect than either cells or electronic computers. Nevertheless, they are still pretty good, perhaps about as faithful as an RNA virus, though not as good as DNA with all its elaborate proofreading measures against textual degradation. Evidence of the fidelity of brains, especially child brains, as data duplicators, is provided by language itself. Bernard Shaw's Professor Higgins was able by ear alone to place Londoners in the street where they grew up. Fiction is not evidence for anything, but everyone knows that Higgins's fictional skill is only an exaggeration of something we can all do. Any American can tell Deep South from Mid West, New England from Hillbilly. Any New Yorker can tell Bronx from Brooklyn. Equivalent claims could be substantiated for any country. What this phenomenon means is that human brains are capable of pretty accurate copying (otherwise the accents of, say, Newcastle would not be stable enough to be recognized) but with some mistakes (otherwise pronunciation would not evolve, and all speakers of a language would inherit identically the same accents from their remote ancestors). Language evolves, because it has both the great stability and the slight changeability that are prerequisites for any evolving system.
The second requirement of a virus-friendly environment - that it should obey a program of coded instructions - is again only quantitatively less true for brains than for cells or computers. We sometimes obey orders from one another, but also we sometimes don't. Nevertheless, it is a telling fact that, the world over, the vast majority of children follow the religion of their parents rather than any of the other available religions. Instructions to genuflect, to bow towards Mecca, to nod one's head rhythmically towards the wall, to shake like a maniac, to 'speak in tongues' - the list of such arbitrary and pointless motor patterns offered by religion alone is extensive - are obeyed, if not slavishly, at least with some reasonably high statistical probability.
Less portentously, and again especially prominent in children, the 'craze' is a striking example of behaviour that owes more to epi- demiology than to rational choice. Yoyos, hula hoops and pogo sticks, with their associated behavioural fixed actions, sweep through schools, and more sporadically leap from school to school, in patterns that differ from a measles epidemic in no serious particular. Ten years ago, you could have travelled thousands of miles through the United States and never seen a baseball cap turned back to front. Today the reverse base- ball cap is ubiquitous. I do not know what the pattern of geographic spread of the reverse baseball cap precisely was, but epidemiology is certainly among the professions primarily qualified to study it. We
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? don't have to get into arguments about 'determinism'; we don't have to claim that children are compelled to imitate their fellows' hat fashions. It is enough that their hat-wearing behaviour, as a matter of fact, is statistically affected by the hat-wearing behaviour of their fellows.
Trivial though they are, crazes provide us with yet more circum- stantial evidence that human minds, especially perhaps juvenile ones, have the qualities that we have singled out as desirable for an informa- tional parasite. At the very least the mind is a plausible candidate for infection by something like a computer virus, even if it is not quite such a parasite's dream-environment as a cell nucleus or an electronic computer. It is intriguing to wonder what it might feel like, from the inside, if one's mind were the victim of a 'virus'. This might be a deliberately designed parasite, like a present-day computer virus. Or it might be an inadvertently mutated and unconsciously evolved parasite. Either way, especially if the evolved parasite was the memetic descendant of a long line of successful ancestors, we are entitled to expect the typical 'mind virus' to be pretty good at its job of getting itself successfully replicated.
Progressive evolution of more effective mind-parasites will have two aspects. New 'mutants' (either random or designed by humans) that are better at spreading will become more numerous. And there will be a ganging up of ideas that flourish in one another's presence, ideas that mutually support one another just as genes do and, as I have speculated, computer viruses may one day do. We expect that replicators will go around together from brain to brain in mutually compatible gangs. These gangs will come to constitute a package, which may be sufficiently stable to deserve a collective name such as Roman Catholicism or Voodoo. It doesn't too much matter whether we analogize the whole package to a single virus, or each one of the component parts to a single virus. The analogy is not that precise anyway, just as the distinction between a computer virus and a computer worm is nothing to get worked up about. What matters is that minds are friendly environ- ments to parasitic, self-replicating ideas or information, and that minds are typically massively infected.
Like computer viruses, successful mind viruses will tend to be hard for their victims to detect. If you are the victim of one, the chances are that you won't know it, and may even vigorously deny it. Accepting that a virus might be difficult to detect in your own mind, what tell-tale signs might you look out for? I shall answer by imagining how a medical textbook might describe the typical symptoms of a sufferer (arbitrarily assumed to be male).
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1. The patient typically finds himself impelled by some deep, inner conviction that something is true, or right, or virtuous: a conviction that doesn't seem to owe anything to evidence or reason, but which, nevertheless, he feels as totally compelling and convincing. We doctors refer to such a belief as 'faith'.
2. Patients typically make a positive virtue of faith's being strong and unshakeable, in spite of not being based upon evidence. Indeed, they may feel that the less evidence there is, the more virtuous the belief (see below).
