Ants follow Fermat's principle of least time

[levlandau]

http://phys.org/news/2013-04-ants-fermat-principle.html

[leephillips]

The original is better: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjourna...

Highly recommended if you enjoy variational principles in physics and are at all interested in biology/cooperative phenomena.