The following appears in my book, Life of Earth: Portrait of a Beautiful, Middle-Aged, Stressed-Out World, published earlier this year by Prometheus Books. I also just finished lecturing about this subject in my evolution class this morning.
The process of natural selection involves these elements: variation; reproduction; limitation. We usually think of genes in this context: natural selection favors the best genes, which must cooperate with other genes to create the best organisms, within populations. But there is nothing about the process of natural selection that requires that the evolvers be organisms. As it turns out, almost everything evolves.
Evolutionary biologist Richard Dawkins pointed out that it is not just genes, but any kind of information, that evolve. Dawkins called non-genetic pieces of information memes, a counterpart to genes. The result is cultural evolution, the counterpart to biological evolution. Cultural evolution turns out to strongly affect biological evolution, because for most complex animals, the most important part of the environment is the culture of its species.
All that is necessary for something to evolve, according to Dawkins, is a faithful but imperfect copying mechanism for instructions, and a system that is ready to obey those instructions. DNA and the cell fulfill these requirements. So do computer programs and computers. And so do memes and the human mind.
A meme can be as simple as an idea. Somebody thinks of an idea, which is a mutant form of some earlier idea that somebody else had. This is the variation step. In the population of human minds, this new idea contributes to the memetic variation of ideas that is available in the culture. The person then tells the idea to another person, or publishes it or sends it. This is the reproduction step. The human mind has a limited capacity for recalling and using ideas. This is the limitation step. The result is that the most successful ideas get propagated in the culture. The less successful ideas remain rare, the arcane knowledge of a few people, or become extinct. The most successful ideas are not necessarily the best ideas, but just the ones that people like the most. For every good and true idea, there are probably a dozen bad and stupid ideas that rattle around in people’s brains. Many of us try to eradicate the bad ideas from our minds, but with only partial success.
Usually, memes are parts of complex sets. As a result, memetic selection not only favors the memes that are most useful to the animals that think or learn them, but work best as part of a memetic set. Human languages are sets of memes. All humans have an innate capacity for language, but they always learn their particular languages from other humans. The result is that languages evolve.
Evolution is like a branching tree. The branches become separate species when the animals no longer recognize one another as potential mates. Languages have the same pattern. The main Indo-European branch of evolution split into smaller branches, one of which was Latin, which then evolved into smaller branches such as Iberian and French, which evolved into twigs such as when Iberian evolved into Spanish, Portuguese, and Catalan. Mutations accumulate in languages, and memetic selection preserves the variations that are most useful or most appealing to the speakers. After awhile, so much divergence has occurred that the speakers may be mutually unintelligible, as when a speaker of Spanish tries to understand French, or when a Parisian pretends he cannot understand a Frenchman from Dijon. An awareness of the branching evolutionary pattern of languages grew during the nineteenth century at the same time as the awareness of biological evolution. A successful word-meme is one that functions best as part of a language, not necessarily by itself.