Complex Contagions and the Diffusion of Innovations: Evidence from a Small-N Study

The recent literature on “complex contagions” challenges Granovetter’s classic hypothesis on the strength of weak ties and argues that, when the actors’ choice requires reinforcement from several sources, it is the structure of strong ties that really matters to sustain rapid and wide diffusion. The paper contributes to this debate by reporting on a small-N study that relies on a unique combination of ethnographic data, social network analysis, and computational models. In particular, we investigate two rural populations of Indian and Kenyan potters who have to decide whether to adopt new, objectively more efficient and economically more attractive, technical/stylistic options. Qualitative field data show that religious sub-communities within the Indian and Kenyan populations exhibit markedly different diffusion rates and speed over the last thirty years. To account for these differences, we first analyze empirically observed kinship networks and advice networks, and, then, we recreate the actual aggregate diffusion curves through a series of empirically calibrated agent-based simulations. Combining the two methods, we show that, while single exposure through heterophilious weak ties were sufficient to initiate the diffusion process, large bridges made of strong ties can in fact lead to faster or slower diffusion depending on the type of signals circulating in the network. We conclude that, even in presence of “complex contagions,” dense local ties cannot be regarded as a sufficient condition for faster diffusion.     

Punctuated Equilibrium Theory and the Diffusion of Innovations

This article builds on punctuated equilibrium theory to evaluate the diffusion of public policy innovations in the United States. The article argues that punctuated equilibrium theory provides a unifying framework for understating three mechanisms leading to the diffusion of innovations: gradual policy diffusion driven by incremental policy emulation, rapid state‐to‐state diffusion driven by policy imitation and mimicking, and nearly immediate policy diffusion driven by state‐level responses to a common exogenous shock. Drawing upon the Bass mixed influence diffusion model, this research generates measures of the coefficients of external and internal influences for diffusion for 81 public policy innovations that have spread across the United States. The article then evaluates how the policy image and direct participation of the federal government contribute to distinct patterns of diffusion over time.     

Ceramic Technology and Social Boundaries: Cultural Practices in Kalinga Clay Selection and Use

This study examines cultural sources of variation in ceramic compositional patterning in two pottery-making villages of the highland Philippines. In Dalupa, many potters are part-time specialists whereas in Dangtalan, women make pottery less frequently. Previous studies show that both pottery form and decoration correspond well with Kalinga social boundaries, but how do morphological and decorative patterning relate to compositional variability? Although researchers have made substantial advances in our understanding of natural and postdepositional sources of compositional variability, little is known about behavioral factors that affect chemical and mineralogical compositional patterning. This study examines cultural practices of clay selection and use in an ethnographic setting, and undertakes technical analyses to assess the relationship between behavior and material culture patterning. Our study identified paste differences between the clays and fired ceramics from Dangtalan and those from Dalupa. Findings from our compositional research thus parallel earlier morphological and stylistic studies, and illustrate multivariate differences in ceramics from these two Kalinga communities. This ethnoarchaeological and analytical project contributes, therefore, to understanding objective parameters within a behavioral context. It also provides an example of how a combined characterization approach, using chemical and petrographic techniques, can yield insights on intraregional variation at a finer scale of resolution than is often attempted.     

Estimating the Size of Social Networks

It is notoriously difficult to define and estimate the size of individuals' social networks. Methods are suggested for estimating the size of such networks, using known rates of mobility together with survey data on the number of acquaintances of individuals who have recently moved. Special attention is given to the likely correlation between mobility rates and network size. Estimates are found to be consistent with previous estimates in the literature. The relation of this approach to multiplicity sampling and to “the small-world problem” is also discussed.     

Beyond the Coastalscapes: Preindustrial Social and Political Networks in East Africa

The archaeological community worldwide now readily recognizes the role and significance of interregional interaction in the development and sustenance of urban societies (e.g., Marcus and Sabloff 2008; Sinclair et al. 2010; Trigger 2003). Over the past two decades, we have carried out a systematic, problem-oriented research program on the Kenyan coast and its hinterland in an effort to understand the ecological and cultural milieu that enabled towns and city-states to develop along the East African coast beginning in the late first millennium CE. Archaeological research complemented with historical sources of the eighteenth and nineteenth centuries shows that different scales of analysis can be used to understand the long-term history of the development of urbanism along this Swahili coast: local, regional, and trans-continental frames of reference each show that Swahili communities were part of numerous networks of interactions. An emerging picture of preindustrial urbanism shows that local, regional, and trans-continental interaction spheres tied coastal towns to the hinterland and to wider Indian Ocean commercial and social networks. Not all of the theorized links between the coastal towns and their local and regional trade and interaction partners will be visible archaeologically. We address the still poorly known elements of preindustrial regional networks of alliance and interaction spheres between urban and rural polities and argue that an integrative approach is necessary to understand the context of coastal urban society.