Richard Dawkins noted the three conditions which must exist for evolution to occur:
- variation, or the introduction of new change to existing elements
- heredity or replication, or the capacity to create copies of elements
- differential “fitness”, or the opportunity for one element to be more or less suited to the environment than another
Dawkins emphasized that the process of evolution naturally occurs whenever these conditions co-exist, and that evolution does not apply only to organic elements such as genes. Memes too, he writes, have the properties necessary for evolution, and thus meme evolution is not simply analogous to genetic evolution, but a real phenomenon subject to the laws of natural selection. Dawkins noted that as various ideas pass from one generation to the next, they may either enhance or detract from the survival of the people who obtain those ideas, or influence the survival of the ideas themselves.
Unlike genetic evolution, memetic evolution can show both Darwinian and Lamarckian traits. Cultural memes will have the characteristic of Lamarckian inheritance when a host aspires to replicate the given meme through inference rather than by exactly copying it. Take for example the case of the transmission of a simple skill such as hammering a nail, a skill which a learner imitates from watching a demonstration without necessarily imitating every discrete movement modelled by the teacher in the demonstration, stroke for stroke.
Clusters of memes, or memeplexes, such as cultural or political doctrines and systems, may also play a part in the acceptance of new memes. Memeplexes comprise groups of memes that replicate together and co-adapt. Memes that fit within a successful memeplex may gain acceptance by “piggybacking” on the success of the memeplex. Meme theory commonly cites memes grouped in memeplexes of religion as examples.