A spectrum of complexity uncovers Dunbar's number and other leaps in social structure

How do societies become more complex? Are there specific scales at which they are reorganized into emergent entities? Social dynamics are shaped by each person's actions, as well as by collective trends that emerge when individuals are brought together. Features like population size, polarization, cohesion, or hierarchy add nuance and complexity to social structure, and might be present, or not, for societies of different sizes. Here we show that, while societal complexity increases monotonically with population, there are specific scales at which complexity builds up faster - one of them is close to Dunbar's number (an estimation of the number of meaningful relationships that individuals can sustain). We have observed this by measuring, as a probe across populations of varied sizes, the sociolinguistic process that has unfolded over decades within the Spanish region of Galicia. For this, we have developed a methodological tool (social complexity spectrum), inspired by theoretical considerations about dynamics on complex networks, that could be applied in further study cases.Teaser: Changes in collective human behavior triggered by a critical population size found through sociolinguistic analysis