Our research advances the hypothesis that more frequent occurrence of solar eclipses is associated with higher complexity in pre-modern societies. To empirically test our hypothesis we exploit variations in the exposure to solar eclipses in a set of 1267 ethnic groups derived from Murdock’s Ethnographic Atlas. Variation in the exposure to total eclipses is exogenous, as eclipses are randomly and sparsely distributed all over the globe, while unlike other natural phenomena, solar eclipses are not associated with any capital destruction. We proxy for social complexity using several different measures: i) the presence of high gods; ii) jurisdictional hierarchy beyond local community; iii) level of political integration; iv) existence of strategy games; and v) class stratification. Our results are robust to a wide range of geographical and ethnic group controls as well as to a horce-race regression between solar and lunar eclipses. As a potential mechanism we hypothesize that solar ecplipses and the fear instilled by them is associated with higher levels of critical thinking, in an attempt to comprehend and eventually control the natural environment. This allows, in turn, better and more complex strategies to use the resources and to cope with changes.