An interesting article from Thom Scott-Phillips has been recently published in the Journal of Cognition and Culture: A (Simple) Experimental Demonstration that Cultural Evolution is not Replicative but Reconstructive – and an Explanations of Why this Difference Matters.
The article describes an experiment that nicely illustrates (“make flesh” in the words of Scott-Phillips) a thought experiment proposed by Dan Sperber. Shortly, imagine a Chinese whispers game, in which chains of individuals have to reproduce two drawings. One is a familiar configuration (in the specific case, the first three letters of the latin alphabet), while the other one is a meaningless scribble (see the image below, from Scott-Phillips’ paper).
Throughout the transmission chains, the former shape is maintained, whereas the latter is not, and it tends to be transformed in something more simple and symmetrical (see the image below, from Scott-Phillips’ paper – “Reconstruction conditions”).
While these results are quite intuitive, I agree with Scott-Phillips (and Sperber) that they exemplify an important point: cultural stability does not need to be supported by high-fidelity social learning. Perhaps the stimulus chosen as “attractor” (i.e. “ABC”) may be misleading as, in fact, it is an attractor only in virtue of the existence of previous high-fidelity social learning: “ABC” would probably not remain stable in a chain composed by individuals that are not familiar with the latin alphabet. But the argument is more general: “attractor” is a statistical notion, and it is a description of what needs to be explained. In this case, previous knowledge of the latin alphabet is one of the “factors of attraction” (I think) that explains the stability of the chain.
From here there are – I agree – far reaching consequences. First, it does not make much sense to concentrate our explicative efforts on a “special” human capacity for imitation or similar. Second, models of cultural evolution that consider the process of transmission as a “replication plus random error” of cultural traits are not modelling what is interesting to model.
Scott-Phillips underlines an important point when he writes:
if […] propagation is reconstructive, then stability arises from the fact that a subclass of cultural types are easily re-producible, while others are not, and hence a casual explanation of stability comes from an explanation of why some types are easily re-producible (and why they are re-produced), while others are not. What differentiates the reproducible from the unreproducible?
Scott-Phillips discusses all the above in a clear and concise way so, if you do not know what I am talking about, please have a look at the paper!
Said so (of course this was coming at some point!), I think that the experiment does not show that “cultural propagation is reconstructive”. In the “Replications Conditions” individuals do not have any problem to reproduce almost exactly the same scribble throughout the chain (see the figure above), showing that cultural transmission can be also strongly preservative, independently from the stimulus presented. The change of the condition is as simple as explicitly asking to the participants to trace the image.
Don’t get me wrong: I believe that the point stressed by Scott-Phillips is extremely important and overlooked by “standard” cultural evolution. I am myself working on very similar matters, and I hope that all these works will converge in a more cognitively-oriented cultural evolution theory. In the same time I feel that to convince cultural evolutionists of the importance of reconstruction in cultural transmission one needs to show that (i) “real” propagation – cultural transmission in the wild – is more similar to the “Reconstruction” than to the “Replication” condition of the experiment, and (ii) this creates interesting differences in the resulting population-level dynamics (probably through modelling). Otherwise, cultural evolutionists will have good arguments to claim that black-boxing cognition is a reasonable strategy when explaining culture. So, let’s all get back to work!