The city in all evidence is much more complex (although probably not much more ancient than good old hammer) but as the hammer it is a product or invention of the human species. Actually, the largest and more complex of all objects produced by humanity. No other living species has produced anything comparable to this major achievement of homo faber. Ants, termites, and bees build fairly complex and widespread nests, and there is a common rhetorical figure that assimilates cities to ant nests. Seen from above, the seemingly chaotic movement of individuals in the streets of the “fourmillant cités” resembles the busy coming and going of black ants in the woods.

And this metaphor has been used particularly to express the fear of oppression from excessive collectivisation and the reduction of individuals to simple mechanical clogs. Miasto, masa, machina was the polish representation of the industrial metropolis rendered immortal by Charlie Chaplin’s entanglement with the fordist factory. The ant-nest metaphor is a highly misleading comparison: the urban setting is a collective system created and continuously changed by the interaction of individuals, it is a social product. Even in the most extreme renderings of Metropolis, as an oppressive collective entity imposing a general conformity, the collective element is the product of human interaction, and deviance a well as periodical revolts occur.

The ant-nest, on the other hand, is a totally individualistic system in which each individual animal is governed by its own dna, there is no collective product, nor any society (or no deviance, since the two are in a sense specular and equivalent terms, as Durkheim points out) in the proper sense. The two products or artefacts are therefore completely different: human cities are perennially changing, while the ant nests are obdurate replicas with only evolutionary long term mutations. It is very likely that the ant nests present on Earth some 120 centuries ago, when the human species embarked in the difficult course of building cities, differed very little from those we can study today.

On the contrary during that same period, we have gone from the primitive abodes of Çatalhöyük to the hi-tech of Frank Gehry or of the Petrona Towers. Leaving aside, for the moment, the corresponding development of diverse social morphologies, given the fact that historical evolution in this area is much more difficult to assess. For this very reason (genetic individualism vs. social interaction) the relation between spaces and functions is fairly strict in the elaborate constructions of ant nests and of termite’s “castles”, but not nearly as strict in the human city, which is a multilayered and multifunctional artefact.

From this point of view, the human city is a highly ambiguous object. First of all because it is complex and large, and as all entities of this kind, difficult to synthesize. Secondly, and above all, because in fact, in each city, and in the general idea of cities, two intertwining but diverse objects coexist. One is the “visible city” which is familiar to every inhabitant of the world in any epoch. Show the image of any unnamed urban area and everyone will immediately recognise it as a city, despite the endless variations of urban forms and types. But there is another city that cannot be seen for it is strictly not visible: not through physical wavelengths at least.

This is the urban society, or the sociological city, which is no less real than the one observable through physical wavelengths, but it is at the same time the maker and the product of the visible city, with which therefore constitutes an inextricable unity. Unravelling this unity can be made in many different ways, but one important tool or lens is to look at the populations constituting a city: the city is a unity but at the same time it is made of many different populations. How do they stick together? This approach was proposed with peculiar cogency by the authors of the so called Chicago School of social ecology.

The idea then was to look at the city as a mosaic of populations each competing for the better parts of the settlement area, succeeding one another as the earlier population got progressively integrated in the community, all the while being segregated, particularly by ethnic groups, by a filtering mechanism which allocated groups and individual on the basis of income, time of arrival, place of origin, race, religion, language, lifestyles and cuisine. The mosaic was kept together despite conflicts and at time violence, precisely because the segregation process shielded large part of the individuals from the shock of competing on the large scale. As acutely discovered by William Foote White in the unsurpassed “Street Corner Society” a research on an Italian neighbourhood in Boston, this arrangement allowed two ways of integration.

The College boys, espousing what we ould today call “yuppie lifestyles” sought integration through individual competition and imitation of the larger values of society, while the much more romantic, but less effectual, Corner boys sought to retain their parochial identity. This mechanism ensured collective integration even if the “melting pot” hypothesis did not materialise, because there was a general shared belief in the America Dream, and in the no-return situation vis-à-vis the Old Country. This is probably why the new immigrants in European cities risk to be kept at the margin: individual, civic or “democratic” integration turns into somewhat of a joke if it does not correspond to real integration in terms of equal chances and, rather than creating general support for society breeds antisystem hatred.