The concept of stigmergy has been used to analyze self-organizing activities in a wide range of domains, from social insects to open source projects. It was introduced in 1959 by the French zoologist Pierre-Paul Grassè. The term derives from the Greek roots stigma, which means “mark or puncture”, and ergon, which can mean “work, action or product of the work”. Grassè defines stigmergy as the stimulation of workers by the achievements of previous activity. The basic principle of this self-organization mechanism is that the action of an agent would leave a trace in the medium that stimulates the execution of the following action by the same or a different agent. The mediation of the environment would guarantee that the tasks are carried out in order, without the need for any planning, control, or direct interaction between the agents. The notion of stigmergy allowed Grassè to propose an explanation to an enigma whose first historical records date back to Ancient Greece, that is, how insects, with very limited intelligence, without apparent communication, organized themselves to deploy complex projects in a cooperative manner.
A consequence of interindividual stimuli would be what has been called the group effect. It describes the fact that when an animal is submitted in certain conditions to a critical number of specific stimuli from its nestmates, our behavior is altered, whose consequence is the emergence of integrative and regulatory processes at the group level.
However, if f stigmergy is such a fundamental and ubiquitous mechanism, why has it taken so long to recognize it? One answer is that the stigmergic coordination mechanism is by definition indirect, while our mind is biased towards capturing the direct causes of the phenomena we observe. If we perceive that the agents act in a coordinated way, our natural inclination is to look for the cause of an agent’s behavior directly in the behavior of another agent, assuming that there is immediate communication between the two. Since we do not find such a direct connection, we assume that the agents are driven by a plan or a leader to control their behavior. We do not intuitively consider the option that an agent can induce the behavior of another agent only by indirect mediation of traces left behind.
 Stigmergy as a universal coordination mechanism (2016), F. Heylighen
 A Brief History of Stigmergy (1999), G. Theraulaz & E. Bonabeau
 The beginnings of entomology in Ancient Greece (1983), Liliane Bodson