The sociological analysis of populations: an application to the tourist phenomenon Daniela Ciaffi, Alfredo Mela 1 Introduction When we speak in everyday language of “population” of an area we use the term in the singular: the living conditions of the population, the welfare of the population, and so on. But in the “ecological” vein of urban sociology – which originated in the Chicago School of the Twenties – the term is often used in the plural, based on a transposition to socio/spatial analysis of concepts deriving from ecology, the science that studies the relations between organisms and their environment. If the anthropised environment in which human societies live can be compared with the habitat of the different animal and vegetable species, why not conceive of such an environment as an ecosystem 2 and refer, instead of to the human “population” as an indistinct group, to the “populations” that make up its different social subgroups? The human ecology approach, then, studies the city as a particular type of ecological system. This is a somewhat partial view, as it neglects many essential aspects of social interaction. Nevertheless, it can easily be traced back to our daily experience. Let us think, for example, of looking at some city images from the viewpoint of the environment/populations relationship. Costa Smeralda: hoteliers and tourists. Milan: white collars, businessmen, new immigrants. Venice: the tourist population beside that of residents and students away from home. Whereas the opposite exercise might be to wonder: what population is missing? In the streets of university campuses, for example, there are usually many fewer housewives than in other urban contexts. To give another example, often people coming from the crowded southern countries of the world, who visit Europe for the first time, ask: but where do you hide the children in your cities?! By and large, the study of populations may suggest a specific way of analysing human presence on the territory: a way that does not clash with other more complex reflections on social interaction, but which, as we will see, offers some important advantages. Let us, then, describe this concept better, referring above all to the use that was proposed of it in the Nineties by Martinotti (1993), with reference to metropolitan populations and their “ways of using” the city.