Richard Dawkins coined the term “meme” to represent small clusters of ideas which are simple, compact, and minimally bundled (and therefore easy to remember). Memes are analogous to genes, and their evolution is governed by the same laws.
Ideological and cultural habitat are selective pressures. For an idea to spread it must be adapted to its environment. Rather than attempting to reach critical mass by convincing a population to accept a new, monolithic world view, it is far more effective to introduce or alter individual memes. Once established in culture, new memes combine with existing beliefs and emotions transforming perception, and ultimately behavior.
Applied to ideas and culture, modularity facilitates hybrid systems, and peaceful evolution.