The great cathedrals of Europe were built over many human lifetimes, and the languages and discourse patterns of our communities have developed over still longer times. And yet a conversation consists of many momentary utterances, a relationship may be built of many strolls and conversations together, a building or a social institution is erected by the sum of many individual actions in a community. Molecules are understood in terms of interactions of atoms, atoms through interactions of smaller particles. In many complex systems, however, this assumption fails. Two distant points along the same stream may interact more than two nearer points not linked by the stream.
Species roam far in the rainforest canopy without ever venturing a few meters down.
In our human ecosocial systems, which are just a specialized kind of ecosystem, people who are linked by the same river, the same railroad, the same phone network, the same chat room on the internet may interact far more than they do with spatially nearer neighbors who are off these social transport and communication networks. In a modern city, spatial proximity may have little relevance to probability or intensity of interaction. The flat view sees only the human scale, indeed only the scale of the moment and the event, privileging that scale in relation to all others. Neither of these essentially spatial views of complex ecosocial systems is satisfactory. The spatial hierarchy model ignores the important role of network toplogies of interaction.