Thursday, 4 July 2013

That which has been copied from

The phenotype/genotype split in cultural evolution remains controversial, with at least four different positions being advocated for: internalism, externalism, informational memetics, and the idea that the distinction is unhelpful and doesn't apply.

However, there's a related distinction that I think everyone could agree on: that systems are divided into those that have been copied from and those that have not. This is the split between ancestors and non-ancestors. The state of having been copied from is the defining characteristic of ancestors.

This classification scheme is relatively simple and unambiguous. It applies equally to the cultural and organic realms. For me, it does a lot of the same work as the phenotype/genotype split - although it is clear that the concept doesn't refer to the exact same thing. Entities that have been copied from are on the germ line. Those that have not been copied from will probably turn out to be phenotypes.

From the perspective of this classification scheme, structures in children are classified as being "genes" because they might be copied from. Structures in mules are classified as being "genes" because they are the kinds of things that are usually copied from. However, such statements contain the qualifiers "might" and "usually" - and so are are rather vague and open to interpretation. So: while the ancestor characteristic is fairly crisp, the phenotype/genotype distinction is less clear.

One of the pieces of work the phenotype/genotype split is used for is to divide genetics from ontogeny - and thus memetics from ontomemy. Could we use the less-ambiguous ancestor characteristic for that purpose instead? Under such a scheme, ontogeny would become the study of those operations that led from recurrently copied information to information that is destroyed before being copied. We could - but I don't think anyone would go for the redefinition. Although being an ancestor is a much more clear cut and uncontroversial concept than phenotypes and genotypes are, it doesn't do exactly the same job.

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