Tuesday, 14 January 2014

Jason Collins on cultural kin selection

Thanks to Jason Collins for recently writing a recent article about cultural kin selection.

Jason is essentially reviewing the paper Cultural transmission and the evolution of human behaviour: a general approach based on the Price equation.

This paper has some problems. Basically, like so much of the cultural evolution literature, it is symbiology-blind. Instead of cultural symbionts, their human hosts are the focus of this paper. The paper writes:

Person A is a cultural ancestor of person B if the value of z person B has was influenced by the value of z person A had

This is not how memeticists look at things. In memetics, the ancestors of cultural traits are other cultural traits. Humans and cultural traits are in different lineages - and so they are not related. A human can't be a "cultural ancestor" of another human - that muddles together the organic and cultural realms.

Cultural traits are the most obvious evolving entities to track in cultural evolution. One can usefully consider the fitnesses and relatedness of monetary units, knots, recipes, songs, phrases - and so forth.

However, the Price equation approach lets the modeller choose how to divide things up. They are free to do this however they like - regardless of whether they are carving nature at the joints or not. Cultural traits - and not their human hosts - are the most obvious thing to track if modelling cultural change using the Price equation.

The approach discussed in the blog post and the associated paper is rather like considering the two humans who share fleas to be related to one another. While it is possible to consider that shared symbionts increase the relatedness of their hosts, it is typically much more useful to consider the fitnesses of the fleas themselves - and their relatedness to each other.

It is true that shared symbionts can cause cooperative behaviours between their hosts. AIDS patients may preferentially associate with other AIDS patients, for instance. In cultural evolution there are more useful examples - shared catholicism memes cause catholics to cooperate with other catholics, for instance. I am not saying that this whole approach is completely useless.

However, it is important to understand that considering memes shared between humans is not the only level of analysis - or even a particularly helpful one. Memes that are shared between my printer and my computer allow them to cooperate, for example. It is important to understand that the billions of sterile cloned dollar bills in circulation are all closely related to one another - and act as sterile workers for the treasury that made them. A focus on the human hosts of cultural traits is a limiting one that misses out the fitnesses and relatednesses associated with cultural traits and cultural artifacts.

Basically, cultural kin selection is much more useful and general than these articles suggest.

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