of influence of the Uruk culture; at its extreme northern edge, the site of Arslantepe had a palace of notable size but it was not surrounded by any kind of urban area. The study of houses at the sites of Habuba Kabira and Jebel Aruda has revealed the social evolution which accompanied the appearance of urban society. The former site, which is the better known, has houses of different sizes, which cover an average area of 400 m2, while the largest have a footprint of more than 1000 m2. The 'temples' of the monumental group of Tell Qanas may have been residences for the leaders of the city. These are thus very hierarchical habitats, indicating the social differentiation that existed in the urban centres of the Late Uruk period (much more than in the preceding period). Another trait of the nascent urban society is revealed by the organisation of domestic space. The houses seem to fold in on themselves, with a new floor plan developed from the tripartite plan current in the Ubayd period, but augmented by a reception area and by a central space (perhaps open to the sky), around which the other rooms were arranged. These houses thus had a private space separated from a public space where guests could be received. In an urban society with a community so much larger than village societies, the relations with people outside the household became more distant, leading to this separation of the house. Thus the old rural house was adapted to the realities of urban society. This model of a house with a central space remained very widespread in the cities of Mesopotamia in the following periods, although it must be kept in mind that the floor plans of residences were very diverse and depended on the development of urbanism in different sites. Development of "symbolic technology", accounting and bureaucracy The Uruk period, particularly in its late phase, is characterized by the explosion of "symbolic technology": signs, images, symbolic designs and abstract numbers are used in order to manage efficiently a more complex human society. The appearance of institutions and households with some important economic functions was accompanied by the development of administrative tools and then accounting tools. This was a veritable 'managerial revolution'. A developed in the Late Uruk period and contributed to the development of a bureaucracy, but only in the context of the large institutions. Many