Weak Ties and Expertise: Crossing Technological Boundaries

In this article, we question how new technological traits can penetrate cohesive social groups and spread. Based on ethnographic narratives and following studies in sociology, the hypothesis is that not only weak ties are important for linking otherwise unconnected groups and introducing new techniques but also that expertise is required. In order to test this hypothesis, we carried out a set of field experiments in northern India where the kiln has been adopted recently. Our goal was to measure the degree of expertise of the potters distributed between early and late adopters of the kiln. Our results are discussed in the light of oral interviews. Our conclusions suggest that expertise is a necessary, albeit not sufficient, condition for weak ties to act as bridges and thereby for new techniques to spread. As an example, they explain how turntables could have been adopted by potters from the northern Levant during the third millennium BC.     

A proxy of potters’ throwing skill: ceramic vessels considered in terms of mechanical stress

This study is aimed at evaluating potters’ skills according to the mechanical characteristics of the vessels they produced. It focuses on wheel thrown vessels. In a first stage, considering that the difficulty of throwing ceramic vessels is to a significant extent determined by the risk of collapse of the thrown structure, we applied the method of finite element modelling to derive an index of mechanical stresses operating within a vessel. Validated via compression tests, the so-called Von Mises stress index was employed as a global index of mechanical difficulty. Because this index allows comparisons between vessels of different form, mass, and clay properties, it provides a more powerful tool than existing techno-morphological taxonomies. In a second stage, in order to relate the Von Mises stress index to throwing difficulty, we analysed the geometrical and mechanical characteristics of vessels thrown by eleven expert potters invited to reproduce four different model forms with two different masses of clay. The results demonstrated that reproductions revealed subtle but systematic deviations from the model forms that allowed a decrease in the mechanical difficulty. More difficult forms showed larger degrees of mechanical optimisation. These results, in combination with a new analysis of data from Roux’s (1990) study with potters of different skill levels, indicate that skill resides, at least to a certain extent, in the capacity to marshal the operative mechanical constraints. In other words, the latter, measured by the Von Mises index, provides a useful signature of a potter’s skills.