Proponents theorize that memes may evolve by natural selection in a manner analogous to that of biological evolution. Memes do this through the processes of variation, mutation, competition and inheritance, each of which influence a meme’s reproductive success. Memes spread through the behaviors that they generate in their hosts. Memes that propagate less prolifically may become extinct, while others may survive, spread and (for better or for worse) mutate. Memes that replicate most effectively enjoy more success, and some may replicate effectively even when they prove to be detrimental to the welfare of their hosts.
A field of study called memetics arose in the 1990s to explore the concepts and transmission of memes in terms of an evolutionary model. Criticism from a variety of fronts has challenged the notion that academic study can examine memes empirically. However, developments in neuroimaging may make empirical study possible. Some commentators question the idea that one can meaningfully categorize culture in terms of discrete units. Others, including Dawkins himself, have argued that this usage of the term is the result of a misunderstanding of the original proposal !