ENDNOTES

[I]

Replicators, interactors and lineages.
The concept 'replicator' used by Dawkins and previously employed by Williams (1966) has been elaborated upon by David Hull (1980, 1988) , Heyes and Plotkin (1989) and Brandon (1988) among others.
Hull uses the concept alongside the concepts 'interactor' and 'lineage', to describe evolutionary processes involving natural selection in biology (1980) ; later he showed them to be a useful scheme in cultural evolution also ( 1982 , 1988 a , b ). Heyes and Plotkin used the replicator-interactor-lineage scheme to criticize Boyd and Richerson (1985) on their work on cultural evolution.
In the replicator-interactor-lineage scheme the concepts are described as follows (Hull, 1980): Processes of replication and interaction result, by definition in evolution of a lineage. The structural entities that are replicated, i.e. the replicators, 'pass on their structure directly from generation to generation'. In principle replicators can only replicate themselves, but they can also produce entities that interact and indirectly result in the replication of the replicators (by reproduction). These entities are known as interactors: 'entities that directly interact as a cohesive whole with their environment in such a way that replication is differential'.
In the paradigm example of evolution by natural selection, a sexual reproducing species, the paradigm replicators are the genes and the paradigm interactors are the organisms. Hull argues that replication or interaction alone cannot account for evolution by natural selection, but that both processes are needed. Selection then becomes defined as: 'a process in which the differential extinction and proliferation of interaction causes the differential perpetuation of the replicators that produced them'. Lineage is the third term in the Hull scheme and refers in this case to the historical changing entity called the species. Notice that Hull thus takes selection to be more than just 'weeding out'. For him selection refers to evolution by selection on replicators that form lineages.

[II]

In 'The Selfish Gene' Dawkins focuses on the selfish or parasitic nature genes can have in biological evolution. Accordingly when making the analogy between genes and memes, he focuses on the parasitic features that memes can have, as an explanation for their dissemination in the memepool. He added the virus to the picture that makes the point of multi-parental dissemination, and also strengthens the word parasitic. One of the examples of this parasitical dissemination concerns religions. Dawkins takes the view that they can spread so well, because humans do not test them for the probability that they might be untrue, or detrimental for the humans holding on to it. He gives examples where religions harm the people that hold onto them.
This view has led to some confusion, for instance in the case where Dennett ( 1991 . page 204) takes beneficial parasites to exist in the form of bacteria in our digestive systems. Dennett also mentions that memes can be detrimental, but that they can also 'bear gifts that will enhance our powers'. Parasites are however detrimental by definition, in contrast to symbiotic entities that are beneficial by definition. Dennett confuses the multi-parental way of dissemination of parasites, with the detrimental effects they can have. I agree with Dennett that memes can spread because they are beneficial, and add that the focus on their possible parasitical nature, in that they are detrimental to their host, is an artefact of the virus analogy.

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