  Models for the behavior of ants and pedestrians are studied in an unified way
in this paper. Each ant follows pheromone put by preceding ants, hence creating
a trail on the ground, while pedestrians also try to follow others in a crowd
for efficient and safe walking. These following behaviors are incorporated in
our stochastic models by using only local update rules for computational
efficiency. It is demonstrated that the ant trail model shows an unusual
non-monotonic dependence of the average speed of the ants on their density,
which can be well analyzed by the zero-range process. We also show that this
anomalous behavior is clearly observed in an experiment of multiple robots.
Next, the relation between the ant trail model and the floor field model for
studying evacuation dynamics of pedestrians is discussed. The latter is
regarded as a two-dimensional generalization of the ant trail model, where the
pheromone is replaced by footprints.
