  Many societies are organized in networks that are formed by people who meet
and interact over time. In this paper, we present a first model to capture the
micro-foundations of social networks evolution, where boundedly rational agents
of different types join the network; meet other agents stochastically over
time; and consequently decide to form social ties. A basic premise of our model
is that in real-world networks, agents form links by reasoning about the
benefits that agents they meet over time can bestow. We study the evolution of
the emerging networks in terms of friendship and popularity acquisition given
the following exogenous parameters: structural opportunism, type distribution,
homophily, and social gregariousness. We show that the time needed for an agent
to find "friends" is influenced by the exogenous parameters: agents who are
more gregarious, more homophilic, less opportunistic, or belong to a type
"minority" spend a longer time on average searching for friendships. Moreover,
we show that preferential attachment is a consequence of an emerging doubly
preferential meeting process: a process that guides agents of a certain type to
meet more popular similar-type agents with a higher probability, thereby
creating asymmetries in the popularity evolution of different types of agents.
