In recent decades economic historians, following Douglass North, have tended to move away from narrowly quantitative studies toward institutional, social, and cultural history affecting the evolution of economies.[5][a 1] However, this trend has been criticized, most forcefully by Francesco Boldizzoni, as a form of economic imperialism "extending the neoclassical explanatory model to the realm of social relations."[6] Conversely, economists in other specializations have started to write on topics concerning economic history.[a 2]