Ants employ a series of well-informed scouts to direct the motion of a group of load-carrying nestmates, finds a study in Nature Communications. This coordination of collective motion optimises the transport of large food items back to the nest, avoiding inefficient tugs-of-war between carriers.
The collective movement of large loads requires a high degree of coordination to avoid inefficiency. Groups of individuals may all conform to the same behaviours, but this inflexibility may lead to decreased responsiveness to change, or the fixation of unwanted behaviours among the whole group.
Ofer Feinerman and colleagues used video analysis to track the motion of individual longhorn crazy ants in a group carrying large food items back to their nest, including cheerios cereal. They find that while the speed at which the load is carried is determined by the number of ants collectively carrying it, the direction in which it travels is influenced by the short-term attachment of individuals who are well informed about the precise location of the nest.
Developing a theoretical model to explain this coordinated behaviour, they find that non informed carriers display an intermediate level of behavioural conformism that allows the well informed individuals to optimally steer the direction of the load. This intermediate behaviour positions the whole group at a critical point between conformism and individuality that is well described by a model more often used to describe emergent phenomena in statistical physics, called the Ising model.