The architecture of present-day protein interaction networks depends on how protein associations evolved. Here, we explore how and why evolution-related mutations influence protein structure to promote protein associations, and thereby network development. We specifically address two questions: (i) How can protein folds remain conserved while proteins accommodate new binding partnerships as genes duplicate? (ii) What is the structural/molecular basis for hub proteins being the most likely to acquire new connections? The answers stem from the examination of the structure wrapping, or protection from water attack. Wrapping is shown to be a crucial consideration in the exploration and evolution of proteomic interactivity.