Collective control without explicit coding: The case of communal nest excavation

The nests of social insects result from a succession of stimulus responses steps involving the environment, the workers, and the by-product of their activities (which modify their environment). In this way social insects can build without any reference to a blueprint. In this paper we explore the link between individual building behavior and the characteristics (form, size, location, etc.) of the structures produced. We show with a mathematical model (in the form of nonlinear differential equations) that social insects using behavioral mechanisms, which do not require an explicit measure of the nest and the colony size, can nevertheless effectively regulate, at the level of the colony, the size of the nest in response to changes in the size of the colony population. In addition, even though individual workers do not directly compare environmental characteristics, the colony can expand the nest preferentially in the most favorable zone. The models used show how such regulations and decision making can be a by-product of an amplifying communication between the builders and their work and how different patterns of building through time can be generated tuning the same basic rules.