Page - (000171) - in Knowledge and Networks

164 shared core positions emerging. Peripheral blocks remain connected, despite the higher centralization of the 1964–1969 period and the reemergence of a distinct core position. Hence, it can be inferred that in normative fields there is high centralization and a core-periphery distinction. With a shift to a competitive field, more spontaneous interactions take place, leading to better distribution of interactions throughout the field. The field again attains a higher centralization, possibly due to stylistic differ- entiation and geographic localism. Yet there is lower core-periphery distinction compared with the 1930–1934 period.6 It is evident that Shooting-Star musicians were prominent in the network (Fig. 8.2b, c) at the dawn of the transition of the jazz field from normative to competitive, In the 1945–1949 period, Elite musicians attained this centrality. However, this achievement of centrality was fairy unstable: Elite musicians across generations displaced each other. Looking at Elite musicians vis-à-vis the blocks in which they are located (Fig. 8.1a–h), it seems, though, that Elite prominence consolidated up to the 1945–1949 period. The distinction between these two sets of analyses sheds light on the value of blockmodeling: While cohesion-based prominence is impor- tant (Fig. 8.2a–h), structural equivalence (Fig. 8.1a–h) allows identification of those musicians who dominate blocks analytically constructed to capture asymmetries across relationships. In substantial terms, if individuals who dominate core blocks are not the same as those whose centrality is cohesion-based, it can be inferred that a loosening has occurred between global and local key players. While the global key players might enjoy higher brokerage gains, local key players may be able to command specific styles, fads, and fashions, as suggested by the prominence of musicians with short-timespan trajectories. In most periods, Elite Cluster musicians dominate the Core blocks in both the normative and competitive field configurations—unsurprising given that this group- ing was obtained by clustering together musicians with high betweenness centrality and long lifespan. However, during the reconfiguration years (from 1945 to 1964), the Elite musicians were also prominent in its cohesion-based centrality. Hence, during the transition from one configuration to another, the Elite musicians played both the high-cohesiveness and high-status roles. But when the field became rela- tively centralized again, and musicians dispersed into distinct styles, younger gen- erations yielded the central position to older musicians. Conclusions Aldrich (1999) suggests that communities evolve in a nested way. He suggests a coevolutionary approach concerned with how sets of populations coevolve over time. From this perspective, trajectories are constrained and supported by a 6 Of course, here I am assuming that the field reached in equilibrium in 1969. Further analyses of right-censored data could show a decline in interperipheral connections. C. Kirschbaum