Sunday, 26 January 2014

The host-centric approach to cultural evolution

I am aware of few defenses within academia of the host-centric approach to cultural evolution. Those involved mostly don't seem to be properly aware that there are other approaches - or think that the other approaches are wrong for unrelated reasons.

One of the few attempted justifications I have encountered comes from Peter Turchin. He once wrote:

I still don’t like these memes and cultural survival machines that are disembodied from real people and human groups. They tend to be treated as a kind of undifferentiated agar growth medium on which the real dynamics take place. Within the framework of multilevel cultural selection we do not need to abstract away from humans and human groups.
It is true that the Price equation allows you to partition cultural variation however you like. However that doesn't mean that the different partitions are equally useful - or equally helpful.

Imagine that someone had said:

I still don't like the idea of smallpox viruses. They tend to be treated as a kind of undifferentiated agar growth medium on which the real dynamics take place. Within the framework of multilevel cultural selection we do not need to abstract away from humans and human groups.
It is technically true that using the Price equation you could model selection and variation caused by smallpox viruses at the level of humans and human groups - and build models that produce useful predictions. The 'pox' trait could be considered to be a property of hosts that spreads horizontally, vertically and obliquely between them. You could track the 'pox' trait - and there would be no need to mention hypothetical smallpox viruses. However, it should be obvious that this process misses a lot - and is an incomplete and impoverished way of modelling the situation.

This is the problem with a huge raft of modern cultural evolution literature within academia - in a nutshell.

One obvious case where humans and human groups is not enough is when modeling memes reproducing and competing within individual minds. In intracranial memetics - you have to "abstract away from humans and human groups" - and go down to the level of the meme.

The host-centrism of so much modern cultural evolution literature can't be part of the coming consensus on cultural evolution. It acts like blinkers on the field, causing massive structural damage to it.

Memetics had this right from the beginning. Many modern students of cultural evolution are perpetuating a problematical approach which was rendered obsolete decades ago.

The most comprehensive critique of the idea that I'm aware of is the book Contagious Ideas: On Evolution, Culture, Archaeology and Cultural Virus Theory by Ben Cullen.

Recently, Steven Shennan has been saying much the same thing as me, writing:

The variation, selection and retention processes that underlie cultural evolution were laid out in detail more than 25 years ago (Cavalli-Sforza and Feldman 1981, Boyd and Richerson, 1985) and have been extensively elaborated on since (e.g. papers in Boyd and Richerson, 2005). However, this has mostly been done from an agent-centred perspective and not from that of the cultural lineages themselves - the "memes eye view" - and the two are not the same.
As far as I can tell, this problem became established in the literature with Boyd and Richerson (1985) - who wrote:

This does not mean that cultures have mysterious lives of their own that cause them to evolve independently of the individuals of which they are composed. As in the case of genetic evolution, individuals are the primary locus of the evolutionary forces that cause cultural evolution and in modelling cultural evolution we will focus on observable events in the lives of individuals.
They meant human individuals. However, in cultural evolution there's a symbiosis involved - with human hosts on one side and cultural symbionts - things like bibles and dogmas - on the other. One should not just focus on the hosts! That misses out half of the creatures involved in the process! Students of "genetic evolution" [sic] typically do not make this mistake - since they have a rich theory of symbiology to draw on.

A possible defense of host-centrism in cultural evolution is that it's a modelling simplification. Simple models can certainly be useful. However, one should not then mistake the simplified model for reality - and something like that appears to be happening in this case. When 99% of the papers discuss the model and very few address the gap between the model and reality, we have a clear case of reification on our hands.

However, it isn't really true that we are dealing with a modeling simplification here. We already have models of symbiology. Adding a whole bunch of new models of cultural evolution that partly duplicate these isn't really a simple approach to the whole topic. If you look at symbiology in the organic realm, few people interested in the spread of symbionts bother with host-only models - they just seem ridiculous. I would classify this as a case of bad models - not just simplified models.

Next year, this awful muddle will have its thirtieth anniversary. It seems to me that it needs to die quickly. Hopefully, explaining the problem clearly will hasten its demise.


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