ties are built and broken when the agents are born and die during the simulation run. Networks Generated from Social Processes Households' social neighbourhood Households in the model have a social neighbourhood space. As actual empirical data on the structure of these networks is a focus of ongoing fieldwork, we have assumed a small-world network with a low clustering coefficient. This assumption is supported by several other studies conducted in the region, e.g. ( Quinlan et al. 2005 ; Ziervogel et al. forthcoming ). Neighbours provide mutual support through lending food etc. to each other. The social neighbourhood also provides support to orphans and dependants of a dissolved household in case the extended family fails to do so. Figure 1 illustrates the households linked by their social neighbourhood. Figure 1 . Example of a social neighbourhood space of the village households in the model. The blue squares indicate households that have accommodated members of dissolved households Agents' friendship networks The model also contains a friendship network comprising of individual agents. Since no empirical data was available from the case study region we based the construction of this network on several simple assumptions. Friendship is a symmetric relation. At initialization, no two friends belong to the same household, but this may change over time as the household compositions change (for example due to marriage). We have restricted the friendship network to adult agents. There is an upper limit (5 -- 7) for the number of friends agents may have at initialization,