Fig. 1.

The longevity of societies plotted against their year of formation for (A) the MOROS database and (B) Seshat database. Red circles are means for time windows each covering 1% of the data. Note that Seshat includes much older polities than MOROS and that those older polities have a much higher recorded longevity. By contrast, MOROS includes modern societies, but longevity drops off for societies starting after 1800 (SI Appendix, Fig. S5). We limited the longevity analysis in the main text to societies forming between 2000 BCE and 1800 CE.