One of the doyens of stigmergic computational intelligence.
There is no master architect, nor even a supervisor in these colonies. Grassé has shown that the key information required to ensure the coordination of building actions performed by insects is provided by their previously achieved work: the architecture itself. Grassé coined the term ‘stigmergy’ from the Greek words ‘stigma’, meaning ‘sting’, and ‘ergon’, meaning ‘work’, to describe this form of indirect communication. For instance, each time an ant or a termite worker executes a building action in response to a local stimulus, such as adding or removing a piece of material from the existing nest structure, it modifies the stimulus that has triggered its action. The new stimulus will then influence other specific actions from that worker, or potentially from any other workers in the colony. The stimulus itself can be a particular pattern of matter sometimes soaked with chemical signals called pheromones. Coordination is simply achieved through judiciously chosen stimulating patterns of matter. And the architecture provides enough information and constraints to ensure the coordination and regulation of building actions. The whole chain of stimuli and behavioural responses leads to an almost perfect collective construction that may give the impression that the whole colony is following a well-defined plan. Thus, individual insects do not need any representation or blueprint to build their nest. At the Centre de Recherches sur la Cognition Animale, part of the Centre National de la Recherche Scientifique (CNRS) at Université Paul Sabatier in Toulouse, we have spent the last 20 years identifying and characterising the interactions involved in the coordination of nest building in various species of wasps, ants and termites. This work has led us to identify similar building principles behind the impressive diversity of insect nest architectures and to build distributed construction models that implement these principles.