SELECTIVE EVENTS AND MEMES

A third cornerstone of the meme-gene analogy next to replicators and replicator pools is (natural) selection. Dawkins tries to use this to explain the spread of memes, although he does not elaborate much on this, he confines himself to competition for 'braintime'. Hull ( 1988a ) presents a more elaborate view on memetic selection in the scientific community.

I believe that selective evolution is relevant for explaining the spread and evolution of meme lineages, memeplexes, and the like. To do this systematically we need to bear in mind the differences between genes and memes as information carriers, and the way they are processed in genetic and social contexts, distinguishing between different kinds of selection, selection pressures, and outcomes of selective events. Below I shall elaborate on three distinctions: selective and non-selective situations, intentional and natural selection, and selection that does or does not involve evolutionary learning.

Selective and non-selective environments

The first distinction is between selective and non-selective evolutionary environments. The example of religions as memetic entities by Dawkins (1989, 1993a ) can show this.

Religions can be seen as entities that can spread through society. A religion can be said to be a set of 'co-adapted' memes: memes that will be more successful in spreading through the soup, when copied together, than if copied alone. Two subsets of memes that are co-adapted and appear in many religions are rules that make believers A) active in ensuring that others believe too, but B) inactive in questioning those rules. In general such a combined group of memes is called a memeplex. That such memeplexes exist could be explained by saying that they copy better together, than if they would spread alone. This presupposes a situation where this memeplex (A and B) has competed with the lonely versions of the memes (A or B), and has won. Thus, a selection process is involved. The selective context here is the fact that people do not have two religions at a time, and only select one (if at all).
However, a religion could also spread and form memeplexes without competing with other religions. If we take a human's choice (intentional or not) for a particular religion to be an example of a selective event, many people have not made such a choice, because they were simply raised with one (or non) religion, and have never been seriously exposed to another one. If a religion simply spreads through society, without competing with other religions, we have a non-selective situation what the religion choice is concerned (of course in view of mind-space, the religion will have competed with other memes that are no part of a religion) [5] . In the no-choice case the religion simply spreads from human to human.
A nice example for two religions that do interact in a selective way is a situation where a child has two parents of different beliefs, and can choose which religion he or she will adopt. Non-selective situations also occur in biology. A similar non-selective example is the introduction of an exotic (not native) species, like the introduction of the rabbit in Australia, which had virtually no selective pressures to deal with (occupied an empty niche), and thus could spread very fast. Most of the examples that Dawkins uses for the dissemination of memes can be called non-selective. The spread of the craze through schools has virtually nothing to do with selection of any kind. A craze just spreads, and dies out. Until a particular spread competes with another one, or does not spread to particular schools, there is no selection.

The distinction between selective and non-selective is also important in deciding whether humans are just vehicles (see Hull, 1988a ) interacting under the control of memes, or if they are the agents by and in which different memes are selected.

If humans execute instructions of memes, or believe the contents of a meme is true, this can be observed by the fact that they don't question the meme itself. Thus the meme is not selected by the human involved, but accepted. If such humans meet others that believe other memes to be true, and both memes can't be true simultaneously, the humans can interact 'in the name of' the memes. When the humans stick to their memes, they are the interactors, since they interact as wholes in the selective event.
If humans on the other hand reject memes, they are like an environment in which memes are selected. In this case competing memes are 'judged' within a brain by some mind process. This can happen unintentionally, when there are no rational criteria, or in a process we denote as 'rational choice', where some known criteria must be present upon which the judgement is based. In both cases the memes are the interactors, even if it is not clear whether they can be said to 'do' anything [6] .
In summary memes can be said to be interactors if they are subject to a selective event inside a person. This can happen rationally, or not. If memes are not rejected by a person, they either have survived a selective event, or are under no selection pressure practised by the human, in which case the human can become the interactor.

Intentional and natural selection

The second distinction is between intentional, artificial or conscious selection and unintentional or natural selection (Hull, 1988a). Genetic selection, without humans involved is always natural. When humans are involved selection can, but does not have to, become intentional.

The distinction between intentional and unintentional not only denotes to the selection process, but also to the process in which variation is produced. Note that this distinction is about characteristics of the mechanisms involved in selective processes, thus only of relevance if there is a selective situation.
For instance in The Origin of Species , Darwin ( 1985 ) gives the example of humans trying to breed animals by selecting the best ones to breed with. Although the introduction of variation in this case is unintentional, the selection is intentionally executed by the breeder. If this breeder would introduce genetically engineered genes in the genome of the animals, the introduction of variation would also be intentional.
The example of breeding is on genetic evolution. In memetic evolution the same distinctions can be made. Replicators are, in the conceptual evolution of science, descriptive (and I add also prescriptive) statements, and theories. Interaction is the testing of these replicators (Hull, 1988a). This testing, analogous to selection, is ideally an intentional affair. By critically bringing a part of the theory into contact with selective criteria a theory can be falsified. In the case of theory a criterium is that it describes or explains relevant phenomena in a scientifically appropriate manner. Other criteria are that the tests should be reproducible, that the explanations are internally not contradictory, and of course that the theory corresponds with empirical reality. However, theories can also be selected in an unintentional way. For example when simply not tested but just ignored without reason, or when not used because it is too difficult to master or understand.

Selection with or without evolutionary learning

The third distinction that I would like to emphasize is between selective events including A) trial and error learning, adaption or in general involving a selective retention system with evolutionary feedback-loops (Vromen, 1994 ), and B) selective events when no such processes are involved.

In genetic evolution the species is the paradigm example of a selective retention system. When Hull mentions evolution by selection such systems are usually presupposed. This kind of selective evolution, can occur if a system can retain what it found out by trial and error to work [7] .
Since natural selection is commonly used for species, and learning for individuals (humans or other animals), I will use evolutionary learning as the word for processes in which trial and error learning in a broad sense takes place. In a selective retention system evolutionary learning takes place. This general class of systems has been described by Campbell ( 1965; 1974 , see also Weick, 1969 ).
In a selective retention system we find the essentials of biological evolution by natural selection: the occurrence of variations, consistent selection criteria and a mechanism for the preservation of positively selected variants. In such a system: 'evolution in the direction of better fit to the selective system becomes inevitable' (Campbell 1965). In this statement the words 'better fit' are equivalent to 'adaptation'.
Campbell links the concept retentionsystem to both natural selection and trial-and error learning 'that have formal parallels'. A selection system in this context is the 'problem' a system has to solve (Campbell, 1974 page 435), and is equivalent to what Brandon ( 1988 ) refers to as 'selective environment'.
The concept of evolutionary learning is a more general description for the way species, or asexually reproducing lineages of organisms or viruses evolve with adaptations occurring over the generations. With the introduction of lineage in this essay, where one mould yielded four slightly different copies, I mentioned that those copies could now compete with regard to some selection pressure (problem). Such a lineage, producing variation, is the most simple example of a selective retention system capable of evolutionary learning in genetic evolution. The individual organism represented by one copy can be said to contain variation (compared to his parent, and his brothers or sisters) in solutions to problems faced in surviving and reproducing. Selective events take care of the destruction of problem-solutions that do not fit as well as others. In a species, feedback about the fit of solutions to the problems is thus given through survival and reproduction of individuals (see Hull 1980 , page 287 for an illustration of the feedback loop of a species). This feedbackloop is what Vromen ( 1994 ) calls an evolutionary mechanism. In his words a mechanism is evolutionary if it works through actual, that is realized past consequences.
When a selective event occurs, evolutionary learning can, but does not have to play a role. In the example of the religion involving instructions A and B, evolutionary learning could have been involved in the production of the memeplex. There could have been one religion with only instruction A. At one time instruction B could have been added, creating a replicated, but altered new 'generation'. In competition for dissemination and survival, the new generation could have won, having an adaption compared to the religion with only instruction A. In contrast to learning by individuals, or adaptations in species, it is not directly obvious what are the elements of the selective retention system in this example.
The situation involving evolutionary learning must be distinguished from a situation where two genealogically unrelated religions compete. While still one religion might win, there is not necessarily anything that adapts by selective evolution: competition does not always yield evolutionary learning.
Memetic evolution involving selective events does not have to involve evolutionary learning. Therefore, the question if evolutionary learning takes place deserves explicit attention in memetic evolution. Hull, as well as Dawkins tend to focus on evolutionary learning events without explicitly mentioning it.
Hull for instance (1988a, b) refers to learning processes in science, while Dawkins ( 1993a ) sketches the possibility of computer viruses becoming selective retention systems with evolutionary learning. However, memetic spread through a unit-pool does not necessarily involve evolutionary learning. Therefore, the learning part in memetic evolution deserves explicit attention.

Summarizing the role of selection in memetic evolution, I have shown that where most theories in genetic evolution presuppose species or lineages of organisms that are selective retention systems, evolutionary learning in memetic evolution is less obvious. Furthermore, memetic evolution can be studied without focusing on selection, like in the case of the craze disseminating through schools. Where selection is involved, it can be intentional or not, involving humans or memes as primary interactors.

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