  There is considerable long-term interest in understanding the dynamics of
collaboration networks, and how these networks form and evolve over time. Most
of the work done on the dynamics of social networks focuses on well-established
communities. Work examining emerging social networks is rarer, simply because
data is difficult to obtain in real time. In this paper, we use thirty years of
data from an emerging scientific community to look at that crucial early stage
in the development of a social network. We show that when the field was very
young, islands of individual researchers labored in relative isolation, and the
coauthorship network was disconnected. Thirty years later, rather than a
cluster of individuals, we find a true collaborative community, bound together
by a robust collaboration network. However, this change did not take place
gradually\textemdash the network remained a loose assortment of isolated
individuals until the mid-2000s, when those smaller parts suddenly knit
themselves together into a single whole. In the rest of this paper, we consider
the role of three factors in these observed structural changes: growth, changes
in social norms, and the introduction of institutions such as field-specific
conferences and journals. We have data from the very earliest years of the
field, a period which includes the introduction of two different institutions:
the first field-specific conference, and the first field-specific journals. We
also identify two relevant behavioral shifts: a discrete increase in
coauthorship coincident with the first conference, and a shift among
established authors away from collaborating with outsiders, towards
collaborating with each other. The interaction of these factors gives us
insight into the formation of collaboration networks more broadly.
