1. Introduction
Complex adaptive systems (CAS) are built on interactions between interdependent agents which process energy, matter
and information, that is, agents with both metabolic and cognitive processes. For example, a human being is developed on
the interactions of different biological subsystems through cognitive (information processing) and metabolic (matter and
energy processing) networks. Also, the emergent properties of societies are built on complex interactions between simple
agents. However, in this case agents are not neurons or other sort of cells, but citizens that consume and produce matter,
energy and information.
CAS evolution can be explained on a temporal axis with two fundamental dimensions (Heylighen, 1999). On the one side,
there is a structural dimension exemplified by the transformation of communications, evolving from centralized societies
with low connectivity between agents to distributed networks (view Fig. 1) with thousands of exchanges per second. On
the other, there is a functional dimension; as it is pointed by Stewart (2000), the progress from hunter-gatherer societies
to transnational communities with high levels of heterogeneity, complex division of labor and wide diversity of cultural
trends. In case a CAS has achieved high structural decentralization and functional heterogeneity, and we project the aforementioned
view to a social system, then we call this state of balance a peer-to-peer (P2P) paradigm.