Ant Mills: The Deadly Cascade
In Chapter 16 we read about information cascades, where people base their decisions on the decisions made by those before them. This often happens because it is the logical thing to do; people aren’t just blindly copying previous decisions, but rather reacting accordingly to a situation created by those previous decisions. In this sense, ignoring those previous decisions, and in turn the environment in which there is a decision to be made, would be a silly thing to do. However, there are times when information cascades can lead to completely nonsensical behaviors. Such a behavior can be occasionally observed in colonies of army ants, in a phenomenon known as an “ant mill”.
Army ants are slightly different from other types of ants in that they are completely blind, and rely almost completely on pheromones left by other army ants to guide themselves through their environment. This is usually an effective way of living, but sometimes proves to be quite detrimental, which is most certainly the case in an ant mill. Ant mills are essentially vortexes of army ants traveling in an endless circle, which will continue to rotate until the ants creating it die of exhaustion. This occurs because the army ants in this “vortex of death” are following the pheromones of the ants in front of them, who are doing the same with ants in front of them, etc.. The ants in the ant mill are all desperately trying to return home, but find themselves in a situation where the blind are literally leading the blind. For better or for worse, it is clear that army ants rely heavily on their own kind of information cascade.
Perhaps ant mills can serve as a sort of cautionary tale about a networking phenomenon that occurs in the daily lives of humans as well. While relying on information cascades can often be logical and time saving, one should always be aware of where the cascade is heading in order to avoid their own “death march” of sorts.
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