Richerson et al. argue that relatively large cultural F[ST] values provide evidence for group structure and therefore scope for group selection. However recent research on spatial patterns of cultural variation demonstrates that as in the genetic case apparent group structure can be a consequence of geographic clines not group barriers. Such a pattern limits the scope for cultural group selection.
Ross, R. M., & Atkinson, Q. D. (2016). Cultural differentiation does not entail group-level structure: the case for geographically explicit analysis. Behavioral and Brain Sciences, 39, 37-38. [e49]. https://doi.org/10.1017/S0140525X15000217