Birds of a Feather
After reading a fellow blog post regarding ants and how they communicate with one another, I began wondering not just about ants, but about other types of swarms- specifically those who stay in large congregations as a method of defense. For instance, flocks of birds or schools of fish- how do they communicate with each other to travel in such organized formations? Do they communicate through a similar use of pheromones or other chemical signals or through a different method? Well, a few minutes of searching led me to the answer, eloquently explained by Cornell’s very own Steven Strogatz.
In a TED talk scraping the surface of the complexities regarding synchronization, Strogatz begins by explaining our ability to clap in unison, and ends with the vibrations in bridges. But in between he covers the concept of swarms, making the seemingly complicated behavior quite comprehensible.
This explanation goes as follows. When one entity encounters a predator, whether that predator be a shark or a hawk or any other great beastie, the natural instinct of that individual is quite obvious- get out of the way! Now his neighbors who are one or two body lengths away, they are immediately aware of his actions. Regardless of the direction they were travelling prior to receiving this signal, all of the neighboring entities decide to mimic the direction of the one fleeing creature. The species that have evolved to live in this swarm like formation have also evolved to understand that when one individual strays from the course of the pack as a whole, there is probably a pretty good reason for it. If they want to save their own hide, scales, feathers, what have you, then they better follow suit and fast. It isn’t that these packs are thinking as a group, carefully choreographing their movements, but rather that each is acting selfishly which remarkably allows information to propagate and ultimately benefit the group as a whole.
At this point, it is probably pretty obvious where I am going with this. This is a very straightforward example of an information cascade- one informed creature makes a decision as to which direction to take based upon the information that a predator is approaching. Of course, its close neighbors probably have also seen this same predator and know to change course as well. Now, the first rule of these swarms is that “all the individuals are only aware of their nearest neighbors.” And these individuals neighboring the fleeing organism have evolved to know that this neighbor is making an informed decision and its best chance of staying alive is to follow suit. These neighbors then abandon any personal information they may have and follow suit, cascading to the edge of the swarm, allowing these “waves of panic to propagate” very efficiently and effectively.
-Sparky Coconut
Source: http://www.ted.com/talks/steven_strogatz_on_sync.html