One of the great lessons that urban planners and analysts can learn from the study of diasporas, is the way in which migrations have a two-fold effect upon the human habitat: population growth in places of reception, and decrease in the original hometowns of the migrants. But the possibility of decreasing has historically been neglected in the science of urban planning, due to the cultural and historical determinations that gave rise to Modern urbanism. Urban science and architectural theory of the last century have considered the city essentially an expansive structure, in perpetual growth: modern urbanism was born in parallel to the rise of the industrial revolution, a historical period characterized by strong demographic growth, which led urban studies to tackle more thoroughly the outcome of expansive developments than that of decrease. It was so, that when the frantic urban expansion in certain areas of Asia or Africa superseded the growth of Western cities, many American and European architectural stars moved to countries such as China or Nigeria as the most exciting hotspots for contemporary urbanism. The most influential architectural theoretician of the last decades, Rem Koolhaas, even said that Europe has ceased to be interesting, because it has stopped growing.
(Images from Detroiturbex.com)