I don’t know about you, but I’ve always found it fascinating to sit and watch ants (especially when I was younger and I had more time).  I always wondered where it was they were trying to go, and how did they know where to go?

The physicist Richard Feynman had also observed ants, and he talks about them in his book “Surely you’re joking Mr. Feynman!”  After conducting a few experiments, he concluded that the ants were following some sort of invisible trail, and that “when an ant has found some food, he leaves a much stronger trail than when he’s just wandering around.”  He also observed that the trail to the food becomes straighter as more ants follow it, and that it gradually “improves” over time.

The invisible trail is a pheromone trail:

https://en.wikipedia.org/wiki/ant

Ants communicate using pheromones that they lay down as trails, so that other ants can follow the trails to food sources.  The trail pheromone evaporates quickly so that when the food supply runs out, the ants know not to follow that trail anymore.

This article:

https://www.msoworld.com/brain/mag/2000/issue1/bpm1_9.html

states that ants exhibit a form of “positive feedback.”  Given the choice between two trails to a food source, over time the ants will prefer to follow the shorter one.  This is probably because ants on the shorter trail make more trips, and therefore lay down more pheromone so the pheromone on the shorter trail becomes stronger.

For more information on this topic, download this PDF entitled “Outsmarted by Ants” by Francis Ratnieks.

https://www.cs.unm.edu/~melaniem/courses/CAS09_files/Outsmarted.pdf