Ant Colony Optimization

We might have seen but not noticed that how these ants follow each other as they don't have eyes to see. The answer to this question is "Ants are behaviorally unsophisticated agents and they collectively perform complex tasks.  Ants have highly developed sophisticated sign-based stigmergy. Ants communicate by using pheromones. Pheromones are the chemical substances which ant release while travelling. Trails are laid that can be followed by other ants. Pheromone evaporate in some time and it accumulates with multiple ants using same path."

Natural Behavior of Ants :

(A) Real ants follow a path between nest and food source.
(B) An obstacle appears on the path: Ants choose whether to turn left or right with equal probability.
(C) Pheromone is deposited more quickly on the shorter path.
(D) All ants have chosen the shorter path.
How Do Ants Work :

Ants wandering for Food

Forming a Pheromone Trail

Trails are Formed

How Pheromone Trails Formed

* Since the route B is shorter, the ants on this path will complete the travel more times and thereby lay more pheromone over it.

      *  The pheromone concentration on trail B will increase at a higher rate than on A, and soon the ants on route  A will choose to follow route B.

      * Since most ants will no longer travel on route A, and since the pheromone is volatile, trail A will start evaporating.

      *  Only the shortest route will remain!