Cumulative Cultural Evolution in Age Structured Populations: a simulation study

Abstract

Cumulative culture, i.e. the knowledge that builds over one another across generations, is considered to be a unique aspect of humans since it provides massive adaptive advantage and allows humans to colonize a wide range of habitats on earth. Culture can be socially transmitted via transmission modes such as vertical (VT), horizontal (HT), and oblique (OT) transmission. These transmission modes have been studied previously in the context of cultural traits which are non-cumulative in nature. We built an age structured individual based model which would capture the effect of pure and mixed transmission modes on cumulative cultural dynamics. Pure transmission modes showed considerable differences in terms of rate of change, complexity reached at equilibrium, as well as the distribution of cultural values at equilibrium. Agreeing with the previous results, the rate of accumulation followed the order HT>OT>VT, however, the complexity of cumulative culture at equilibrium followed the order OT>VT>HT, suggesting the efficiency of transmission modes would depend on the time frame in which one is comparing them. The comparison of mixed transmission modes, in the form of ‘agriculturalist’ and ‘hunter-gatherer’ learning life histories, showed that, keeping all else equal, agriculturalist strategy can sustain more complex cumulative culture than the hunter-gatherers. Further, populations with higher survival showed higher ability to sustain complex cultures. Comparison of learning mechanisms, defined in terms of cost and hierarchy, in tandem with pure transmission modes showed that learning from elders would help reach higher complexity at equilibrium in majority of the cases. Age structure plays a key role in explaining all the results. At the end we suggest several directions in which one can expand this model.