Scientific Reports just published a very interesting article by Matthew Brashears titled “Humans use Compression Heuristics to Improve the Recall of Social Networks“.
Here’s the abstract:
The ability of primates, including humans, to maintain large social networks appears to depend on the ratio of the neocortex to the rest of the brain. However, observed human network size frequently exceeds predictions based on this ratio (e.g., “Dunbar’s Number”), implying that human networks are too large to be cognitively managed. Here I show that humans adaptively use compression heuristics to allow larger amounts of social information to be stored in the same brain volume. I find that human adults can remember larger numbers of relationships in greater detail when a network exhibits triadic closure and kin labels than when it does not. These findings help to explain how humans manage large and complex social networks with finite cognitive resources and suggest that many of the unusual properties of human social networks are rooted in the strategies necessary to cope with cognitive limitations.
This paper is potentially an important contribution to the literature that studies how large social network structures emerge as unintended consequences of individual choices. The question how humans deal cognitively with large complex network structures has been lingering in this literature for a while, with for example game theorists routinely assuming that actors are capable of observing and understanding the entire network in a large population. Brashears’ results will help to replace such obviously unrealistic assumptions with better ones. What it also great is how Brashears gets to these results with relatively simple experimental procedures such as vignette experiments.
However, I think that Brashears jumps a little too far with his conclusions when he writes in the discussion that
These findings show that humans adaptively make use of schemata as compression heuristics to store social information more efficiently. This permits humans to develop and maintain social networks that are substantially larger than might be expected based on their neocortical ratios…Networks that can be more easily represented in the mind (e.g., adhere to schemata) can reach larger absolute sizes and provide a competitive advantage.
This looks like a classic micro-macro fallacy to me: just the fact that human are better capable of recalling certain types of network structures does yet tell us how these network structures would emerge, let alone whether there would be a competitive advantage. For sure, the extent to which humans can cognitively comprehend large network structures will affect their choices in creating their network, but the the overall network structure is still the collective effect of the many interdependent choices of the individuals in the network, and predicting the resulting network is a much more complex (and unsolved) puzzle than Brashears seems to suggest.