Sunday, 5 January 2014

Alberto Acerbi on the differences between organic and cultural evolution

Memetics takes the relationship between the organic and cultural realms more seriously than any other theory of cultural evolution I am aware of. However, the close parallels seen by memeticists are not always shared by cultural evolution enthusiasts in academia. Alberto Acerbi helps us to highlight this difference in perspective today. To him, the close parallel seems wrong - and he explains why.

He recently posted about the differences between organic and cultural evolution on his blog. Here's one of his comments:

Moreover, a part from having effects in cultural dynamics, regulatory traits represent a difference between cultural and biological evolution. This is an “hot” topic in modern cultural evolutionary theory so I do not want to go in depth here (let me just say at least that I think it is interesting to study also the differences between the two evolutionary processes). “Rules” of genetic transmission tend to not be under genetic control, and models of cultural evolution inspired by evolutionary biology tend to consider the rules of cultural transmission (for example the propensity to learn from others) in the same way not under “cultural control” (they are usually considered under genetic control).

...and here's my reply - in which I explain why I regard the parallel as being closer:

Surely, everyone believes that the rules of genetic transmission are under genetic control! Probably, you are talking about how easy the rules are to change by making genetic modifications.

Note that, if you are comparing genetic with cultural evolution, you should really be looking at whether the capacity of organisms to transmit DNA-based symbiotes (e.g. gut bacteria, and parasites) is easy to change by making genetic modifications. In which case, you will see that the way in which such genes are transmitted is relatively malleable. It is easy enough for genetic changes to make an organism more or less likely to sneeze, for instance.

If you adopt this perspective on evolution in the organic realm, you will see that the case of DNA-based symbionts turns out to be closely comparable to the case of cultural symbionts - with respect to how easy it is for DNA to modulate the transmission pathways involved.

If anyone has ever reasoned from organic evolution to cultural evolution - arguing that since genetic transmission is not easy for genes to regulate, it will not be easy for culture to regulate cultural transmission - then probably their understanding of the dynamics of genetic transmission is faulty. There's no need to question their understanding of the relationship between organic evolution to cultural evolution on these grounds - since this is an example of where these processes are very similar. There are, in fact, plenty of known cases where genes can easily regulate the transmission pathways of other genes residing in symbionts.

In the associated paper, the authors say:

Although more flexible modalities of gene transfer exist [34, 35], genes typically propagate to offspring from just two (sexual reproduction of chromosomal DNA) or one parent (asexual reproduction or sexual reproduction of mithocondrial DNA). Cultural information instead can be transmitted in many different ways and, potentially, from any individual to any other individual, which creates the opportunity to regulate the flow of information in a more fine–grained and context–dependent way.
Cultural information typically propagates from one (or sometimes more) parents to offspring as well. However, the parents aren't human, they are cultural. For example, the parent of a bible is typically another bible. To conceptually mix together human hosts with cultural descendants would be to muddle together cultural and organic evolution. If you do that, you typically do get into a muddle about these issues - but the solution is to not do that. Humans aren't the "parents" of cultural information. They are the parents of their own children. Cultural information is unrelated to them. It's in a completely different lineage, which almost never recombines with human genes.

In both the organic and cultural realms, symbionts may potentially be transferred from any individual to any other individual. Organic symbionts - such as flu viruses may be passed between any two individuals. Similarly, in cultural evolution, bibles may be passed between any two individuals. The situation is a pretty close parallel in this regard. That's because both cultural and organic evolution are implementations of universal Darwinian rules.

Of course, there are differences between cultural and organic evolution - but they are more subtle than this. A failure to recognize the similarities results in existing work not being reused - and reinvention-of-the-wheel syndrome. Also, exaggeration of the differences hampers the development of a unified theory that covers both the cultural and organic realms. We have known about the importance of symbiosis for a long time. Culture is well modeled within a biological framework using the idea of cultural symbionts - and the existing theory of symbiosis - as was recognized long ago by the cultural evolution pioneers Ted Cloak and Richard Dawkins.

It is frustrating for me to see modern students of cultural evolution struggling to understand the topic without using the concept of symbiosis. In 2011, Alex Mesoudi managed to write a whole book on the topic without event mentioning concepts from symbiosis at all. To me, it all seems a bit like time-traveling back to the 1950s - before the idea of symbiosis was widely understood.


1 comment:

  1. Hi Tim, I report here the answer I gave you in my original post - even though I am sure it will not satisfy you :-)

    In the post I squeezed our argument in just few sentences [...] To me, the problem is mainly pragmatic (i.e. how much complexity do you want to put in your models of [cultural/genetic] evolution?). Population genetic has been built on models that make the simplifying assumption that rules of genetic transmission are immutable, and this strategy has been proved successful. The question we ask in the paper is whether the same simplifying assumption can be safely made in models of cultural evolution.
    More generally I do not see this as black/white distinction. I agree that genes can and do regulate their transmission pathways, but I think that in cultural evolution this effect is way more important.