A decade ago, Henrich proposed group size as a driver of cultural complexity. Derex et al. now present experimental results they say support this ‘group size hypothesis’ by seemingly showing that larger groups perform better than smaller groups under imitation-based cultural evolution. Our re-analysis of their experimental data, however, shows that larger groups actually perform worse than smaller groups. Thus, contrary to their claim, their data are consistent with empirical evidence discounting the group size hypothesis for non-food producing societies. In their argument, Derex et al. assume that showing that larger groups produce complex artefacts more often than do smaller groups suffices for supporting the group size hypothesis. But such an increase can arise just through a sample size effect. Furthermore, the increases in probabilities associated with group size, are even less than what would be expected from the sampling size effect. We believe, therefore, that their data fail to support the group size hypothesis.
Read also: Demography and cultural evolution