Sunday, 27 July 2014

Exposure order matters with DNA too!

One old and persistent fallacy relating to differences between organic and cultural evolution involves the claim that order of exposure to ideas matters - whereas that isn't true for DNA genes.

My foil in this case will be Felix Aurioles, who recently wrote:

It is because of this ambiguity that we must distinguish between behaviors or cultural traits, and the pieces of information that form them. There remains a likeness with genetics; when a phenotype is successful it propagates itself along with the information that encodes it. The difference lies, in that while a certain combination of genes always codes for a particular phenotype; the forms of cultural traits depend not only of the “memes” that compose them, but on the order they were absorbed and on the particular social circumstances they entered the culture.
My reply is as follows:

Gene expression is often context dependent - and it is often untrue that "certain combination of genes always codes for a particular phenotype". Instead, genes and environment interact during development to produce a phenotype. This happens in both organic evolution and cultural evolution.

It is also untrue that exposure order is not relevant to DNA-genes. For example, exposure to Hepatitis D followed by exposure to Hepatitis B has quite different outcomes to the reverse order of exposure. That is because Hepatitis D is a satellite of Hepatitis B - i.e. it requires its presence to reproduce.

In organic evolution, a pathogen-caused immune deficiency disease (e.g. AIDS) might leave a hole in your immune system through which another pathogen (e.g. tuberculosis or pneumonia) might find easy entry. Similarly in cultural evolution a "faith is good" meme might compromise your memetic immune system - and leave you vulnerable to a "the end of the world is nigh" meme.

This sort of thing is a fairly common phenomena for DNA-based parasites - e.g. look into "opportunistic infections". The cultural equivalent is cultural opportunistic infections.

To effectively compare organic evolution and cultural evolution, you have to have some understanding of how both processes work. Only understanding one of them is not enough. Many critics of memetics from the social sciences often seem to think that whatever smattering of evolutionary biology and genetics they have picked up is enough to allow them to venture forth public criticisms based on their knowledge of these topics - and quite often they are mistaken.

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