For something to count as a replicator it must sustain the evolutionary algorithm based on variation, selection and retention (or heredity). Memes certainly come with variation - stories are rarely told exactly the same way twice, no two buildings are absolutely identical, and every conversation is unique - and when memes are passed on, the copying is not always perfect. As the psychologist, Sir Frederic Bartlett (1932) showed n the 1930s, a story get a bit embellished or the details are forgotten every time it is passed on. There is memetic selection - some memes grab the attention, are faithfully remembered and passed on to other people, while others fail to get copied at all. Then, when memes are passed on there is retention of some of the ideas or behaviors in that meme - something of the original meme must be retained for us to call it imitation or copying or learning by example. The meme therefore fits perfectly into Dawkin's idea of a replicator and into Dennett's evolutionary algorithm.

Where do new memes come from? They come about through variation and combination of old ones - either inside one person's mind, or when memes are passed from person to person. So, for example, the poodle story is concocted out of language that people already know and ideas they already have, put together in new ways. They then remember it and pass it on, and variations occur in the process. And the same is true of inventions, songs, works of art, and scientific theories. The human mind is a rich source of variation. In our thinking we mix up ideas and turn them over to produce new combinations. In our dreams we mix them up even more, with bizarre - and occasionally creative - consequences. Human creativity is a process of variation and recombination.

In thinking about thinking we should remember that not all thoughts are memes. In principle, our immediate perceptions and emotions are not memes because they are ours alone, and we may never pass them on. We may imagine a beautiful scene from memory, or fantasize about sex or food, without using ideas that have been copied from someone else. We may even, in principle, think up a completely new way of doing something without using any memes from anyone else. However, in practice, because we use memes so much, most of our thinking is coloured by them in one way or another. Memes have become the tools with which we think.

From the early days of Darwinism analogies have been drawn between biological evolution and the evolution of culture. Darwin's contemporary Herbert Spencer studied the evolution of civilizations, which he viewed as progressing towards an ideal something like that of Victorian English society. Lewis Morgan's evolutionary theory of society included the three stages of savagery, barbarism, and civilization. The historian Arnold Toynbee used evolutionary ideas in identifying over thirty distinct civilizations some of which were derived from others and some of which went extinct, and even Karl Marx used evolutionary analogies in his analysis of society. Fifty years after Darwin, the American psychologist James Baldwin said that natural selection was not merely a law of biology but applied to all the sciences of life and mind, an early version of Universal Darwinism (Baldwin 1909), and he coined the term 'social heredity' to describe the way individuals learn from society by imitation and instruction (Baldwin 1896).

Nowadays, comparative linguists analyse the minute details of similarities and differences. They can often trace words back through many types of change such as the dropping of syllables and shifts in pronunciation. Thus, the evolutionary history of various languages can be accurately traced. Family trees based on differences in DNA. Also, the migratory histories of whole peoples can be deduced from the languages that remain today. In Africa, for example, the 1500 or more surviving languages fall into just five main language groups, largely spoken by distinct racial groups, and their distribution can reveal which groups defeated others in the past. From a few remaining words it can be deduced that the pygmies once had their own languages but were forced into adopting those of neighbouring black farmers, and that Semitic languages, the languages of the Bible and of Islam, came not from the Near East but from African.

A seriously maladaptive example is the practice of cannibalism in the funeral rites of a New Guinea highland tribe called the Fore. As part of complex rituals honouring their dead the Fore ate parts of the human bodies. In fact, they preferred eating pork to human flesh and so the men tended to get more of this prized food, leaving the women and children to more cannibalism (Durham 1991). This practice led directly to an epidemic of the degenerative disease kuru, which killed about 2500 Fore people, mostly women and children. Cavalli-Sforza and Feldman demonstrated mathematically that a maladaptive trait like this could eliminate up to 50 percent of its carriers and still spread through a population.

Can you stop thinking?

Perhaps you have practiced meditation or some other method of calming the mind. If so you will know that the task is not trivial. If you have not, I suggest you try now to empty your mind for a minute or so (or if you cannot face it now, try it sometime when you have nothing 'better' to do, waiting for the kettle to boil, or the computer to boot up, for example). When any thought comes along, as it certainly will, just acknowledge it and let it go. Do not get tangled up in the thoughts or follow them up. See whether you can find any space between them. The simplest forms of meditation are no more than this kind of practice. It is fiendishly difficult.

Why? You will doubtless ntice that thoughts just seem to pop up out of nowhere and grab your attention. You may also notice what kinds of thought they are. Typically, they are imagined conversations or arguments, reruns of events with new endings, self-justifications, complicated plans for the future, or difficult decisions that have to be made. They are rarely simple images, perceptions or feelings (which can come and go without causing trouble); rather, they use words, arguments, and ideas you have acquired from other people. In other words, these incessant thoughts are memes. 'You' cannot command them to cease. You cannot even command them to go slower nor tell yourself not to get sucked into them. They seem to have a life and power of their own. Why?

From the biological point of view this constant thinking does not appear to be justified.

Think of the number of things you are likely to say to someone else today -- or the number of words you will hear other people speak. You might listen to the radio, watch television, have dinner with other people, help your children with the homework, answer the phone to people far away. Most of what is said in these conversations will never be passed on again. Most of it will not reappear as 'Then he said to her...' or 'And did you know...' Most will die at birth.

Written words may not fare much better. The words on this pag have at least got as far as being read by you, but may well get no further. Even if you do pass them on, you may scramble them for easier recall or because I have not made myself clear, so the copying fidelity will not always be high. Millions of newspapers are printed each day but by a week a later most of the copies have gone and most people have forgotten what was in them. Books may do a little better -- though in the United States alone something like one hundred thousand new books are published every year. Not all of them can be influential or memorable. And while some scientific papers are widely read and quoted, it is rumoured that the majority are nto read by anyone at all!

Recent research shows that babies begin to imitate facial expressions and gestures from an early age whether they are rewarded or not. Babies are able to mimic facial expressions they see and sounds they hear when they are too young to have learned by practice or by looking in mirrors (Meltzoff 1990). Successfully imitating something seems to be rewarding in itself. We can see now, as the behaviourists could not, why so much of our behavior has to be instinctive. The world is too complicated to cope with if we have to learn everything from scratch. Indeed, learning itself cannot get off the ground without inbuilt competencies. We humans have mroe instincts than other species, not fewer. As Steven Pinker puts it 'complexity in the mind is not caused by learning, learning is caused by complexity in the mind.'

The taboo against homosexuality is especially interesting. There is not generally accepted biological explanation of homosexuality and superficially it does not appear to be adaptive. Nevertheless, evidence is accumulating that there is an inherited predisposition for homosexuality. Assuming this is the case, the taboos of the past would, paradoxically, have favoured the survival of these genes by forcing the people who carried them, against their wishes, to marry and have children.

This suggests an interesting prediction for the future. As horizontal transmission increases the taboo should lose its power and so can be expected to disappear, as indeed it is doing in many societies. Homosexuals are then free to have sex with other homosexuals, to have long-term relationships with their own sex, and not to have children at all. The short-term effect is much more overt homosexual behavior and acceptance of that behavior by everyone, but the long-term effect may be fewer genes for homosexuality.

Let us suppose that women who have many chidren are far too busy to have much social life, and spend most of their time with their partners and family. The few other people they do see are likely to be other mothers with young children who already share at least some of their child-rearing memes. The more children they have the mor eyears they will spend this way. They will, therefore, have little time for spreading their own memes, including the ones concerned with family values and the pleasures of having lots of children.

On the other hand, women who have onlyh one or two children, or none at all, are far more likely to have jobs outside the home, to have an exciting social life, to use e-mail, to write books and papers and articles, to become politicians or broadcasters, or do any number of other things that will spread their memes, including the memes for birth control and the pleasures of a small family. These are the women whose pictures appear in the media, whose succss inspires others, and who provide role models for other women to copy.

There is a battle going on here -- a battle between memes and genes to take controle over the machinery of replication -- in this case a woman's body and mind. Any one person has only so much time and energy in their lifetime. They can divide it as they choose but they cannot have lots of children and devote maximal time and effort to spreading memes. This particular battle is played out largely in the lives of women and is becoming ever more important as women take a more prominent role in modern meme-driven society. My argument is simply this -- the women who devote more time to memes and less to genes are the more visible ones, and therefore the ones most likely to be copied. In the process, they are effectively encouraging more women to desert gene-spreading in favour of meme-spreading

Whether by coincidence or by memetic transmission, Beethoven is the favourite example for illustrating this problem. Brodie (1996) uses Beethoven's Fifth Symphony, Dawkins (1976) uses the Ninth and Dennett (1995) uses both the Fifth and the Seventh. Dennet adds that the first four notes of Beethoven's Fifth are a tremendously successful meme, replicating all by themselves in contexts in which Beethoven's works are quite unknown. So are they the meme, or the whole symphony?

If we cannot answer this question we cannot identify the unit of the meme, and some people clearly think this is a problem for memetics. For example, many years ago Jacob Bronowski wondered why we do not have a better understanding of social change and blamed our not being able to pin down the relevant units (Hull 1982).

Effective memes will be those that cause high fidelity, long-lasting memory. Memes may be successful at spreading largely because they are memorable rather than because they are important or useful. Wrong theories in science may spread simply because they are comprehensible and fit easilty with existing theories, and bad books may sell more copies because you can remember the title when you get to the bookshop -- though, of course, we do have strategies for overcoming these biases. An important task of memetics will be to integrate the psychology of memory with an understanding of memetic selection.

Some people argue that memes are not digital (Maynard Smith 1996) and that only digital systems can support evolution. Certainly genes are digital and certainly digital storage is far preferable to analogue. We all know that digital video- and audio-recordings look and sound better than their analogue predecessors; a digital system allows information to be stored and transmitted with far less loss of information even over noisy channels. However, there is no law that says that evolution has to be digitaly based -- the issue is really one of the quality of replication.

What, then, makes for a good quality replicator? Dawkins (1976) sums it up in three words -- fidelity, fecundity, and longevity. This means that a replicator has to be copied accurately, many copies must be made, and the copies must last a long time -- although there may be trade-offs between the three. Genes do well on all three counts, and being digital gives them high fidelity copying. So what about brains?

[Cloak] defined the i-culture as the instructions in people's heads, and the m-culture as the features of people's behaviour, their technology and social organization. he explicitly likened his i-culture to the genotype and m-culture to the phenotype... in The Extended Phenotype [Dawkins] says 'Unfortunately, unlike Cloak... I was insufficiently clear about the distinction between the meme itself, as replicator, on the one hand, and its "phenotypic effects" or "meme products" on the other' (Dawkins 1982, p. 109). He then went on to describe the meme as the structure physically realised in the brain.

Dennet (1995) also talks about memes and their phenotypic effects, but in a different way. The meme is internal (though not confined to brains) while the design it shows the world, 'the way it affects things in its environment' (p. 349), is its phenotype. In an almost complete reversal, Benzon (1996) likens pots, knives, and written words (Cloak's m-culture) to the gene, and ideas, desires and emotion (i-culture) to the phenotype. Gabora (1997) likens the genotype to the mental representation of a meme, and the phenotype to its implementation. Delius (1989), having defined memes as being in the brain, refers to behaviour as memes' phenotypic expression, while remaining ambiguous about the role of the clothes fashions he discusses. Grant (1990) defines the 'memotype' as the actual information content of a meme, and distinguishes this from its 'sociotype' or social expression. He explicitly bases his memotype/socio- type distinction on the phenotype/genotype distinction.

If my understanding of human nature is that there is no conscious self inside then I must live that way--otherwise this is a vain and lifeless theory of human nature. But how can 'I' live as though I do not exist, and who would be choosing to do so?

One trick is to concentrate on the present moment--all the time--letting go of any thoughts that come up. This kind of 'meme-weeding' requires a great concentration but is most interestin in its effect. If you can concentrate for a few minutes at a time, you will begin to see that in any moment there is no observing self. Suppose you sit and look out of the window. Ideas will come up but these are all past- and future-oriented; so let them go, come back to the present. Just notice what is happening. The mind leaps to label objects with words, but these words take time and are not really in the present. So let them go too. With a lot of practice the world looks different; the idea of a series of events gives way to nothing but change, and the idea of a self who is viewing the scene seems to fall away.

Another way is to pay attention to everything equally. This is an odd practice because things begin to lose their 'thingness' and become just changes. Also, it throws up the question of who is paying attention (Blackmore 1995). What becomes obvious, in doing this task, is that attention is always being manipulated by things outside yourself rather than controlled by you. The longer you can sit still and attend to everything, the more obvious it becomes that attention is dragged away by sounds, movements, and most of all thoughts that seem to come from nowhere. These are the memes fighting ti out to grab the information-processing resources of the brain they might use for their propagation. Things that worry you, opinions that you hold, things you want to say to someone, or wish you hadn't--these all come and grab the attention to everything disarms them and makes it obvious that you never did control the attention; it controlled--and created--you.

These kinds of practices begin to wear away at the false self. In the present moment, attending equally to everything, there is no distinction between myself and the things happening. It is only when 'I' want something, respond to something, believe something decide to do something, that 'I' suddenly appear. This can be seen directly through experience with enough practice at just being.

This insight is perfectly compatible with memetics. In most people the selfplex is constantly being reinforced. Everything that happens is referred to the self, sensations are referred to the observing self, shifts of attention are attributed to the self, decisions are described as being made by the self, and so on. All this reconfirms and sustains the selfplex, and the result is a quality of consciousness dominated by the sense of 'I' in the middle--me in charge, me responsible, me suffering. The effect of one-pointed concentration is to stop the processes that feed the selfplex. Learning to pay attention to everything equally stops self-related memes from grabbing the attention; learning to be fully in the present moment stops speculation about the past and future of the mythical 'I'. These are tricks that help a human person (body, brain and memes) to drop the false ideas of the selfplex. The quality of consciousness then changes to become open, and spacious, and free of self. The effect is like waking up from a state of confusion--or waking from the meme dream (Blackmore in press).

We should think of it like this - evolutionary theory describes how design is created by the competition between replicators. Genes are one example of a replicator and memes another. The general theory of evolution must apply to both of them, but the specific details of how each replicator works may be quite different.

This relationship was clearly seen by the the American psychologist Donald Campbell (1960, 1965) long before the idea of memes was invented. He argued that organic evolution, creative thought and cultural evolution resemble each other and they do so because all are evolving systems where there is blind variation among the replicated units and selective retention of some variants at the expense of others. Most importantly, he explained that the analogy with cultural accumulations is not from organic evolution pe se; but rather from a general model of evolutionary change for which organic evolution is but one instance. Durham (1991) calls this principle 'Campbell's Rule'.