The complexity of some cultural domains, such as technology, seems to be linked to population size. This makes intuitive sense: after all, we have iPhones and rockets, whereas hunter-gatherer societies do not. How does this work, however, for other, non-technological, cultural domains? Western stories are not more complex than Aboriginal Australians ones (I guess). What about religions, or kinship systems?
I recently published, together with Olivier Morin, a paper in Cognition and Emotion: Birth of the cool: a two-centuries decline in emotional expression in Anglophone fiction. The main result is about a clear decrease in the emotional tone in English-language literature, starting plausibly from the XIX century, a decrease driven almost entirely by a decline in the proportion of positive emotion-related words, while the frequency of negative emotion-related words shows little if any decline. In other words, English literature became in the last centuries less “emotional” and, in particular, less “positive”.
[The first part is here]
In a successive series of models, published in Scientific Reports, we considered whether other individual-level mechanisms could potentially be mistaken for conformity, generating relations between frequency of a trait and probability to copy it that looked like sigmoids. We choose a few simple and plausible mechanisms (you can refer to the paper for details) and we found that two of them – on a total of seven tested, plus three controls – generated relations for which a sigmoid function produced a better fit than a linear one (see figure below). The codes for running all simulations (written in Matlab) are available through the Open Science Framework.
I recently did some modelling work, in collaboration with Edwin van Leeuwen and others, exploring possible confounds in conformity research. As I discussed in a post some time ago, “conformity”, in cultural evolution, has a precise meaning as a disproportionate tendency to copy the majority. “Disproportionate” here means that the probability to copy a popular cultural trait should be higher than the frequency of the trait itself. In other words, if 60% of your friends wear read, and 40% wear blue, not only you should be more likely to also wear read (this would happen also by copying at random), but your probability to wear read should be higher than 60%. Why is this important? Conformity, in this technical sense, allows majority behaviours to be resistant to random fluctuations, or to changes in population, like migrations, etc. This, in turn, contributes to maintain stable cultural differences between groups.
I’ve just uploaded on SocArXiv a new preprint, A cultural evolution approach to digital media, where I suggest (surprise!) that cultural evolution provides some interesting tools to analyse digital media.