  Specialization and hierarchical organization are important features of
efficient collaboration in economical, artificial, and biological systems.
Here, we investigate the hypothesis that both features can be explained by the
fact that each entity of such a system is limited in a certain way. We propose
an information-theoretic approach based on a Free Energy principle, in order to
computationally analyze systems of bounded rational agents that deal with such
limitations optimally. We find that specialization allows to focus on fewer
tasks, thus leading to a more efficient execution, but in turn requires
coordination in hierarchical structures of specialized experts and coordinating
units. Our results suggest that hierarchical architectures of specialized units
at lower levels that are coordinated by units at higher levels are optimal,
given that each unit's information-processing capability is limited and
conforms to constraints on complexity costs.
