  Faculty hiring networks-who hires whose graduates as faculty-exhibit steep
hierarchies, which can reinforce both social and epistemic inequalities in
academia. Understanding the mechanisms driving these patterns would inform
efforts to diversify the academy and shed new light on the role of hiring in
shaping which scientific discoveries are made. Here, we investigate the degree
to which structural mechanisms can explain hierarchy and other network
characteristics observed in empirical faculty hiring networks. We study a
family of adaptive rewiring network models, which reinforce institutional
prestige within the hierarchy in five distinct ways. Each mechanism determines
the probability that a new hire comes from a particular institution according
to that institution's prestige score, which is inferred from the hiring
network's existing structure. We find that structural inequalities and
centrality patterns in real hiring networks are best reproduced by a mechanism
of global placement power, in which a new hire is drawn from a particular
institution in proportion to the number of previously drawn hires anywhere. On
the other hand, network measures of biased visibility are better recapitulated
by a mechanism of local placement power, in which a new hire is drawn from a
particular institution in proportion to the number of its previous hires
already present at the hiring institution. These contrasting results suggest
that the underlying structural mechanism reinforcing hierarchies in faculty
hiring networks is a mixture of global and local preference for institutional
prestige. Under these dynamics, we show that each institution's position in the
hierarchy is remarkably stable, due to a dynamic competition that
overwhelmingly favors more prestigious institutions.
