By Susan Milius
A novel analysis shows how individual ants’ behavior keeps the traffic flowing as 200,000 virtually blind army ants use a single trail to swarm out to a raid and return home with the booty.
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The South American army ant Eciton burchelli avoids epic gridlock by forming traffic lanes on its trail, explains Iain D. Couzin of Princeton University. The ants don’t follow people’s simple stay-to-the-right (or left) paradigm. Instead, they create three lanes–the outer two carrying raiders to the job and the middle one returning them to the nest. This pattern can develop from just the basic behavioral tendencies of individual ants, say Couzin and Nigel Franks of the University of Bristol in England in an upcoming Proceedings of the Royal Society of London B.