As soon as the primeval soup provided conditions in which molecules could make copies of themselves, the replicators themselves took over.
For more than three thousand million years, DNA has been the only replicator worth talking about in the world. But it does not necessarily hold these monopoly rights for all time.
Whenever conditions arise in which a new kind of replicator can make copies of itself, the new replicators will tend to take over, and start a new kind of evolution of their own.
Once this new evolution begins, it will in no necessary sense be subservient to the old.
The old gene-selected evolution, by making brains, provided the soup in which the first memes arose. Once self-copying memes had arisen, their own, much faster, kind of evolution took off.
We biologists have assimilated the idea of genetic evolution so deeply that we tend to forget that it is only one of many possible kinds of evolution.
Imitation, in the broad sense, is how memes can replicate. But just as not all genes that can replicate do so successfully, so some memes are more successful in the meme pool than others. This is the analogue of natural selection.
I have mentioned particular examples of qualities that make for high survival value among memes. But in general they must be the same as those discussed for the replicators of Chapter 2: longevity, fecundity, and copying-fidelity.
The longevity of any one copy of a meme is probably relatively unimportant, as it is for any one copy of a gene. The copy of the tune ‘Auld Lang Syne’ that exists in my brain will last only for the rest of my life.* The copy of the same tune that is printed in my volume of The Scottish Student’s Song Book is unlikely to last much longer. But I expect there will be copies of the same tune on paper and in peoples’ brains for centuries to come.
As in the case of genes, fecundity is much more important than longevity of particular copies. If the meme is a scientific idea, its spread will depend on how acceptable it is to the population of individual scientists; a rough measure of its survival value could be obtained by counting the number of times it is referred to in successive years in scientific journals.
If it is a popular tune, its spread through the meme pool may be gauged by the number of people heard whistling it in the streets. If it is a style of women’s shoe, the population memeticist may use sales statistics from shoe shops.
Some memes, like some genes, achieve brilliant short-term success in spreading rapidly, but do not last long in the meme pool. Popular songs and stiletto heels are examples. Others, such as the Jewish religious laws, may continue to propagate themselves for thousands of years, usually because of the great potential permanence of written records.
This brings me to the third general quality of successful replicators: copying-fidelity. Here I must admit that I am on shaky ground.
At first sight it looks as if memes are not high-fidelity replicators at all. Every time a scientist hears an idea and passes it on to somebody else, he is likely to change it somewhat.
I have made no secret of my debt in this book to the ideas of R. L. Trivers. Yet I have not repeated them in his own words. I have twisted them round for my own purposes, changing the emphasis, blending them with ideas of my own and of other people.
The memes are being passed on to you in altered form.
This looks quite unlike the particulate, all-or-none quality of gene transmission. It looks as though meme transmission is subject to continuous mutation, and also to blending.