stigmergy

thumb|Ant paths built from pheromone traces Stigmergy ( ) is a mechanism of indirect coordination, through the environment, between agents or actions. The principle is that the trace left in the environment by an individual action stimulates the performance of a succeeding action by the same or different agent. Agents that respond to traces in the environment receive positive fitness benefits, reinforcing the likelihood of these behaviors' becoming fixed within a population over time.

Stigmergy is a form of self-organization. It produces complex, seemingly intelligent structures, without need for any planning, control, or even direct communication between the agents. As such it supports efficient collaboration between extremely simple agents, who may lack memory or individual awareness of one another. By offloading memory to the environment (as stigmergic traces), and computation to interaction between agents and traces, complex distributed cognition is performed by remarkably simple organisms. This form of cognition long predates neurons in evolutionary history.