The theory of the “(first) demographic transition” (DT) still has considerable practical relevance in the field of population research. For instance, the DT serves as a conceptual model that underlies the UN’s population projections, and is central to the discussion around the so-called “demographic dividend”. Although it was first described 90 years ago, several questions related to the DT remain open or need verification. In particular, there is debate about the question of what the indispensable triggers of the DT are. Assumptions regarding the primary causes include increased education for women and related changes in values, as well as economic development, urbanisation, migration, and the democratisation process. This paper aims to co...