Total - Energies

Text : Marie Le Breton
Human beings are not the only creatures to suffer from traffic jams. Ants, too, generate very heavy traffic when they are out bringing back food for the nest. In the absence of traffic lights or “ant cops” at the intersections, how do they manage to move about so efficiently all summer? It all starts when a worker-ant goes out exploring. When the scout heads back to the nest, it leaves behind chemical traces (pheromones), thus blazing a pioneer trail for the other ants to follow right to the treasure-trove of food. As the other ants set off along the food trail, they, too, leave traces of pheromone, thus increasing the concentration of the chemical. This stimulates the insects and helps them to find their way, but as they are all on the same path it also increases traffic density. So what happens when “peak hour” arrives, and collisions between hurrying ants impede the efficiency of their harvest? The ants’ solution is to divide their traffic flow into two separate paths leading to the same place. A research program combining a detailed ethological study of ant behavior with mathematical modelling techniques has now enabled researchers to express this mechanism in equations, showing that the switch from an asymmetrical to a symmetrical traffic flow occurs as soon as it becomes more efficient for the insects to move along separate paths. Following very simple behavioral rules, the ants adapt automatically to the constraints of their milieu. This study, carried out by an international research team*, will give us a better understanding of how a few simple driving rules (suitable speed, choice of lane, etc.) can regulate overall road-traffic behavior. Ants have shown the way; now all we have to do is follow it.
* Paul Sabatier University, Toulouse; France’s National Research Center (CNRS); the Free University of Brussels; the Technological University of Dresden.