We thank Tosh et al. (1) for their interest in our research (2) but note that their analyses do not undermine the main findings of our article. Their suggestion that polity population divided by polity area should be one of the social complexity dimensions raises a number of issues. What does this ratio mean at large spatial scales, where populations are concentrated in large urban centers and much of the territory is not heavily populated? How are societies distributed across this variable and why? For example, a small-scale “simple” society could have a very high population density if it has access to a rich resource base. Tosh et al. (1) do not provide sufficient information or context to meaningfully …

T- E. Currie, P. Turchin, et al., Reply to Tosh et al.: Quantitative analyses of cultural evolution require engagement with historical and archaeological research, PNAS 115(26) (2018) E5841-E5842