Semantic maps, to which Johan van der Auwera has brought a major intellectual contribution, are a representation of implicational relations in the typological domain. They have increasingly been used to chart historical evolution. They are arranged as a series of contiguous cells that define pathways of variation and change. The questions raised concern the rationale for the contiguity arrangement. It is demonstrated on the basis of novel diachronic analyses that the cells making up a semantic map should be semantic functions and that the contiguous arrangement of these functions relates to the existence of bridging contexts. Because evolution from one function to the next is made possible by bridging contexts, a specific pathway of function pairs defines the evolution of items that can only proceed between cells that share bridging contexts.