Created by ThinkQuest Team C004404

Real ants are not only capable of finding shortest path from a food source to the nest without using visual cues, they are capable of adapting to changes in the environment.

 

The main means used by ants to form and maintain the line is a pheromone trail. Ants deposit a certain amount of pheromone while walking, and each ant prefers to follow a direction rich in pheromone rather than a poorer one. This ants can be used to explain how ants can find the shortest path which reconnects a broken line after the sudden appearance of an unexpected obstacle has interrupted the initial path  

 

In fact, once the obstacle has appeared, the ants which are just in front of the obstacle cannot continue to follow the pheromone trail and therefore they have to choose between turning right or left. In this situation we can expect half the ants to choose to turn right and the other half to turn left.  

 

Ants which choose the shorter path around the obstacle will more rapidly reconstitute the interrupted pheromone trail compared to those which choose the longer path. Hence, the shorter path will receive a higher amount of pheromone in the time unit and this will in turn cause a higher number of ants to choose the shorter path.  

 

The most interesting aspect of this auto catalytic process is that finding the shortest path around the obstacle seems to be an emergent property of the interaction between the obstacle shape and ants distributed behavior: Although all ants move at approximately the same speed and deposit a pheromone trail at approximately the same rate, it is a fact that it takes longer to contour obstacles on their longer side than on their shorter side which makes the pheromone trail accumulate quicker on the shorter side. It is the ants preference for higher pheromone trail levels which makes this accumulation still quicker on the shorter path.