Population turnover, behavioural conservatism, and rates of cultural evolution

Cultural evolution facilitates behavioural adaptation in many species. The pace of cultural evolution can be accelerated by population turnover where newcomers (immigrants or juvenile recruits) introduce adaptive cultural traits into their new group. However, where newcomers are naïve to the challenges of their new group, population turnover could potentially slow the rate of cultural evolution. Here, we model cultural evolution with population turnover and show that even if turnover results in the replacement of experienced individuals with naïve ones, turnover can still accelerate cultural evolution if (a) the rate of social learning is more than twice as fast as the turnover rate and (b) newcomers are more likely to learn socially than behaviourally conservative existing group members. Although population turnover is a relatively simple factor, it is common to all animal societies and variation in the turnover rate may potentially play an important role in explaining variation in the occurrence and rates of adaptive cultural evolution across species.