Swarms as smart architects: understanding construction dynamics in ant colonies
Guy Theraulaz, Centre de Recherches sur la Cognition Animale, Universite Paul Sabatier (March 17, 2011)
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The amazing abilities of social insects to solve their everyday-life problems, also known as swarm intelligence, have received a considerable attention the past twenty years. Among their collective behaviors, nest building is certainly the most spectacular. Not only the characteristic scale of the nests is typically much larger than the size of the individuals, but some of the architectures built by insect colonies can also be highly complex. All along the evolution of these animals, there has been a whole set of innovations in terms of architectural designs and construction techniques that proved to be efficient to solve a large number of problems such as controlling the nest temperature, ensuring the gas exchanges with the outside environment or adapting the nest structure to various colony sizes. One fundamental question is: how large-scale patterns are generated by the actions and interactions of individual insects? To investigate this issue, we focused on the early stages of nest construction in the ant Lasius niger. This experimental paradigm was used to disentangle the coordinating mechanisms at work and characterize the individual behaviors (transport and assemblage of construction material). We then developed a 3D model implementing the mechanisms detected on the individual level and showed that they correctly explain the construction dynamics and the patterns observed at the collective level for various conditions. The model also revealed that complex helicoidal structures connecting nearby chambers emerge from a constant remodeling process of the nest architecture.