  We study the self-assembly of a complex network of collaborations among
self-interested agents. The agents can maintain different levels of cooperation
with different partners. Further, they continuously, selectively, and
independently adapt the amount of resources allocated to each of their
collaborations in order to maximize the obtained payoff. We show analytically
that the system approaches a state in which the agents make identical
investments, and links produce identical benefits. Despite this high degree of
social coordination some agents manage to secure privileged topological
positions in the network enabling them to extract high payoffs. Our analytical
investigations provide a rationale for the emergence of unidirectional
non-reciprocal collaborations and different responses to the withdrawal of a
partner from an interaction that have been reported in the psychological
literature.

Physics and Society