Cooperation in Balinese Rice Farming by J. Stephen Lansing and John H. Miller
This great article explains in clear terms how Balinese rice farmers acting in self interest and following a few simple rules have caused the emergency of a large scale system that tends to maximize rice yields given the prevailing constraints.
For centuries Balinese rice farmers have engaged in cooperative agricultural practices. Without centralized control, farmers have created a carefully coordinated system that allows productive farming in an ecosystem that is rife with water scarcity and the threat of disease and pests.
It seems to me that P2P computing networks are in some ways analogus to the rice famers networks of fields and irrigation channels. Yet they have so far failed to produce any large scale emergent features, unless you count the destruction of the music industry as an emergent feature! The current crop of P2P systems seem to lack the simple rules that lead to emergent properties. I suspect it will not be too long before we see P2P systems that feature these simple rules and produce large scale emergent features.