The first act of design was almost certainly user design, in that the plan was created by the user rather than by a third-party designer. Perhaps this first user designer contemplated frustration with a task tens of thousands of years ago, formed a plan to address the frustration, and then fashioned an artifact, possibly shaping a stick of wood into a digging implement. A clear distinction between expert designers and user designers emerged at some point possibly first in the domain of architecture. Certainly by the time ancient Egyptians were creating pyramids, the roles of experts and users in design were separated. This separation was probably motivated by the comparative advantage of experts over users in designing enormous structures. The activity of design appears to have become increasingly professional and institutionalized over the next few thousand years. By the 19th Century, as the industrial revolution developed in full, expert designers with specific technical training assumed distinct professional roles, both because of the comparative advantage of expertise and because institutions were formed to exploit the benefits of mass production.