Do social learning and conformist bias coevolve? Henrich and Boyd revisited.

We studied the coevolution of social learning and conformist bias in a modified version of the Henrich and Boyd [1998. The evolution of conformist transmission and the emergence of between-group differences. Evol. Hum. Behav. 19, 215-241] model that nevertheless preserves its essential features. The convergent stable strategies (CSS) are identified by a numerical adaptive dynamics method and then checked for evolutionary stability. A strategy that is simultaneously a CSS and an ESS is called an attractive evolutionarily stable strategy (AESS). Our main findings are as follows. First, the AESS reliance on social learning is monotone increasing in the fixed interval between environmental changes and monotone decreasing in the quality of environmental information. Second, the AESS strength of conformist bias is monotone non-increasing in the fixed interval between environmental changes and monotone non-decreasing in the quality of environmental information. The first observation is in agreement with Henrich and Boyd (1998), but the second is in direct contradiction. In addition, we conducted Monte Carlo simulations as in Henrich and Boyd (1998), which supported our findings. We believe that the reason for the discrepancy with regard to the strength of conformist bias is that Henrich and Boyd (1998) did not allow a sufficient number of iterations for true convergence to occur. In conclusion, the conditions favoring a heavy reliance on social learning are not the same as those favoring a strong conformist bias.