While in class, we learned about the mechanisms of evolution of life. There are four ways that life develops. Anyways, I got the idea that maybe the same mechanisms apply to ideas. I will describe each mechanism, how it applies to life, and the analogy to ideas using Christianity as a particular example of an idea.
Natural selection is generally what you think of when you hear "survival of the fittest." The main idea is that the fit organisms reproduce, passing their genes to the next generation while the others don't. In the case of a finch, those with the stoutest beaks on an island of hard nuts wouldn't starve as often and so have more stout-beaked finches. Also, a fit animal must produce offspring that can themselves reproduce. An animal that has sterile offspring has no fitness.
"Fitness" then is defined generally by the ability to pass on genes. Actual survival value is not always necessary. For example, peacocks are very poor fliers because of their huge tails; but those with big tails mate better, so flight is sacrificed for appearance.
For ideas, 'fit' ideas are those which are passed on. The Gospel, for example, has excellent fitness, as it has been passed on from a single individual to now around 2 billion. Gnosticism went extinct because of the superior fitness of Christianity. The "fitness" of a Christian, then, is his or her ability to transmit that faith to others. Also, if these converts do not themselves convert others (are 'sterile'), then the Christian is not fit.
Truth is like survival value; truth increases believer's ability to live fulfilled lives (e.g. people who believe in loving their neighbor as themsleves lead more fulfilled lives than those who don't). Like survival value, it is not necessary for a fit idea to be true; like exaggerated tail feathers, false ideas that look good may transmit despite the detriment to the believer.
Genetic drift is the natural variations in the expected based on chance. It's like how a blue eyed woman and a brown eyed man may have four blue-eyed children. It's most likely they would have two blue-eyed and two brown-eyed children, but it just didn't turn out that way. In a population, the incidence of blue eyed individuals may be like this family and go up simply due to chance. This is genetic drift.
The effects of genetic drift are increased when populations are small. In the case of the family (initial population size of 2), the brown-eye gene was completely eliminated in the next generation simply by chance. This is much less likely with large populations; the population's genetics don't drift as far when the population is large.
Ideas can also vary greatly from any initial starting point. Christianity has strayed, greatly at times, from the original teachings of Jesus. It could be said that the idea of justification by faith completely disappeared in the Western European population of Christians in the early middle ages.
This effect is pronounced when populations are small. Cults form when too few people isolate themselves from the rest of the population. Early in the church when the population was tiny, heresy abounded in the Gnostics and Judiazers.
Gene flow is transfer of genetic material between populations. It's like a brown eyed person moving to Holland to get married. A brown-eye gene will be transferred to the Dutch population which doesn't have very much of it. Gene flow works to limit genetic drift. In other words, it makes populations seem bigger (genetically) than they are. There are more genes available, so drift is lessened.
Like genes, humans can exchange information through writing. With ideas, collaboration keeps ideas from drifting. Paul's letters allowed isolated and small populations of believers in Ephesus to limit their tendency to drift towards heresy. Likewise with science, the Literature and the peer-review process prevents the flow of ideas from drifting.
Here is the fun one. Mutation is a random change in the genes of an organism. It may be caused by a mutagen (like in Ninja Turtles), or even something as simple as sunlight (UV is particularly nasty to DNA). This process eventually leads to the creation of new genetic material and thus new adaptations which, if they increase the fitness of an organism, would be maintained in the population. Mutations, however, are almost always detrimental and usually are eliminated in the first generation. Mutation is the only mechanism that can actually create new genetic information; all other processes only manage or modify existing information.
In ideas, mutation seems to correlate with revelation or epiphany. Most of human interaction is exchanging old ideas (gene flow). It is very rare that anyone thinks of anything novel. Rather, it is rare that a novel idea is actually fit (people pass it on) or true. There are many, many new ideas that are wrong and stupid that people have but no one repeats.
Focusing again on Christianity, Jesus was the first to introduce this new idea to the world; it turned out to be very fit and very true so survived and was passed on. It can be said that people like Paul, Aquinas and Luther may have all added information and ideas to Christianity that were truly novel and passable. In Luther's case, he caused an insertion of information that had been lost due to the "genetic drift" of the Catholic church during the Middle Ages.
Anyways, it was a fun thing to think about. I have not thought out the implications or further applications of this idea as yet.