We have undertaken to model trajectories of development and demise of Bronze Age settlement systems for both the rain-fed and irrigated zones of Syria and Iraq. In both regions, settlements attained their maximum size in the 4th or 3rd millennium BC and declined in either the late 3rd or 2nd millennium BC. The city-region, in the form of the urban center, with its subsidiary settlements and land-use zones, forms a more appropriate analytical unit than the city itself, and this framework of analysis will be extended still further to include a much larger interaction sphere of information and commodity flow than the city region itself. Within such settlement-land-use systems, larger centers appear to have grown as a result of positive feedback that resulted in increasing numbers of people being attracted to the city through time. Such growth was then constrained by processes of negative feedback so that cities appeared not to have exceeded a certain size. Neighboring centers could be expected to grow in a similar manner, and a dynamic quasi-equilibrium state (but not stasis) may have developed so that a series of semiautonomous "city states" appeared. Such entities were not stable, however. As archaeological and text-based studies demonstrate, these systems are unstable in the long term and are vulnerable to abrupt declines as a result of external shocks or internal malfunctions.

Early urban settlements in the Near East provide an ideal laboratory for the study of human-environmental interactions because they offer an enormous array of data drawn from archaeological and textual studies that can be incorporated into an overall social, economic, and environmental analytical framework over long stretches of time. Using the ancient Near Eastern city as a particularly well-documented example of long-term settlement, this research will:

1. Address how and why in the 3rd and 4th millennia BC, cities in the irrigated zone of southern Mesopotamia grew to a greater size than those in the rain-fed north.
2. Examine the dynamic trajectory of such settlements through time, and how they responded to a capricious natural environment and were able to grow, survive, or decline under various cultural, environmental, and economic stresses.
3. Demonstrate the ability to move from a static data set (archaeological and environmental records) to dynamic modeling that incorporates feedback mechanisms, system integration, and nonlinear responses to a wide range of input data.

Settlement-land-use systems are being modeled from the ground up, that is, from the smallest social element (the household) to much larger entities such as networks of interacting cities. The outcome of the modeling is being tested and validated by a broad framework of data established by combining the results from archaeological excavations, regional archaeological surveys, satellite remote sensing, and regional-scale environmental studies. Such analyses will supply ancient settlement distributions, inferred land-use patterns, and traces of relict landscapes and communication networks that can be used to compare with the output of the modeling framework.