Looking at the richness and complexity of life on Earth, Dawkins realised that genes alone were simply not enough to explain evolution from the simplest forms to the complexity of man, his culture and societal organisation. So he applied a Darwinian view to culture as well. Dawkins argued for the concept of memes - ideas that are "viruses to the brain", analogous to viruses that affect a PC. Memes are to culture what genes are to biology. A meme for, say, astrology, could parasitize a mind just as surely as a hookworm could infest someone's bowels. Ideas - like genes - can compete and cooperate, mutate and conserve, by some form of natural selection.
Cultural evolution, including the evolution of knowledge, can be modelled through the same basic principles of variation and selection that underly biological evolution. This implies a shift from genes as units of biological information to a new type of units of cultural information: memes.
A meme is a cognitive or behavioral pattern that can be transmitted from one individual to another one. Since the individual who transmitted the meme will continue to carry it, the transmission can be interpreted as a replication: a copy of the meme is made in the memory of another individual, making him or her into a carrier of the meme. This process of self-reproduction (the memetic life-cycle), leading to spreading over a growing group of individuals, defines the meme as a replicator, similar in that respect to the gene (Dawkins, 1976; Moritz, 1991).
Dawkins listed the following three characteristics for any successful replicator:
In these general characteristics, memes are similar to genes and to other replicators, such as computer viruses or crystals. The genetic metaphor for cultural transmission is limited, though. Genes can only be transmitted from parent to child ("vertical transmission"). Memes can be transmitted between any two individuals ("horizontal transmission" or "multiple parenting"). In that sense they are more similar to parasites or infections (cf. Cullen, 1998).
For genes to be transmitted, you need a generation. Memes only take minutes to replicate, and thus have potentially much higher fecundity (see Competition between Memes and Genes). On the other hand, the copying-fidelity of memes is in general much lower. If a story is spread by being told from person to person, the final version will be very different from the original one. It is this variability or fuzziness that perhaps distinguishes cultural patterns most strikingly from DNA structures: every individual's version of an idea or belief will be in some respect different from the others'. That makes it difficult to analyse or delimit memes. This does not imply that meme evolution cannot be accurately modeled, though. After all, genetics was a well-established science long before the precise DNA structure of genes was discovered.
Examples of memes in the animal world are most bird songs, and certain techniques for hunting or using tools that are passed from parents or the social group to the youngsters (Bonner, 1980). In human society, almost any cultural entity can be seen as a meme: religions, language, fashions, songs, techniques, scientific theories and concepts, conventions, traditions, etc. The defining characteristic of memes as informational patterns, is that they can be replicated in unlimited amounts by communication between individuals, independently of any replication at the level of the genes.
Modelling memes
Memetics can be defined as an approach trying to model the evolution of memes . Memes undergo processes of variation (mutation, recombination) of their internal structure. Different variants will compete for the limited memory space available in different individuals. The most fit variants will win this competition, and spread most extensively. This spreading can in principle be modelled mathematically (see e.g. Boyd & Richerson, 1985; Cavalli-Sforza & Feldman, 1981; Lumsden & Wilson, 1981; Csanyi, 1991; Lynch, 1998), although in practice it will be very difficult to determine the exact values of the parameters of the model. A more practical, qualitative approach is to formulate specific criteria for the fitness of a meme, relative to other memes, taking into account the subsequent stages of the memetic life-cycle.
As is the case with genes, it is not necessary to know the exact coding or even the exact size or boundaries of a meme in order to discuss its fitness, and thus to make predictions about its further spreading, survival or extinction within the population of competing memes. Such predictions can be empirically tested. For example, a memetic hypothesis might state that simpler memes will spread more quickly. This can be tested by observing the spread (perhaps in a controlled environment) of two memes that are similar in all respects, except that the one is simpler. Theories can also be induced from empirical observation of meme behavior "in the wild" (see e.g. Best, 1998). Given the differences in variation and selection mechanisms, it is also possible to make predictions about the competition between memes and genes.
Variation, replication and selection on the basis of meme fitness determine a complex dynamics. This dynamics will be influenced by the medium through which memes are communicated, and the copying-fidelity, fecundity and longevity it allows. Perhaps the most powerful medium for meme transmission is the computer network, and this implies some specific characteristics for memes on the net.
Created on ... juillet 16, 2003