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Nature’s Solution to Braess’s Paradox

In searching for a blog topic, I came across this panel discussion of how human traffic relates to swarming and flocking behavior in the natural world. I found it particularly interesting when one of the speakers discussed ants and their spontaneous organization of pheromone trails. Even though some ant societies can contains as many as 20 million individuals, they are remarkably efficient in forming traffic patterns to search for and retrieve food. What is particularly amazing about this is that these complex patterns emerge from every individual ant following very simple behavioral rules. One example mentioned in the talk is that if a trail of ants heading one way encounters a sister carrying food back in the opposite direction, the trail will spontaneously split into two lanes and give the returning ant a clear path in recognition of its higher priority. There is no centralized authority dictating the behavior of the colony, and the queen is little more than a reproductive organ for the colony. In fact, due to a genetic quirk of ants that make sisters more closely related to each other than mothers are to their daughters, the ant colony can thought of as a super-organism. Each individual ant acts on behalf of the colony, and the whole system only works with an extreme degree of cooperation.

Human traffic patterns, on the other hand, are dictated by self-interest and a lack of communication. We’ve already seen in class how people choose highway routes to minimize their total travel time. We also saw how this selfish behavior can lead to Braess’s paradox, where adding and additional route can make overall traffic flow more congested. What this video helped to reveal, however, is the some of the biological and evolutionary factors that influence this behavior. Humans evolved to cooperate in relatively small tribal societies that never had to face significant travel congestion. Unlike swarms of locusts or schools of fish, we don’t have built in mechanisms to direct movement in large groups. We need a centralized authority to determine infrastructure, laws, and signals to dictate traffic flow. The human analogy to the diverging ant lanes that I discussed above would be something like cars pulling over in response to an ambulance or firetruck with its siren on.  Overall, however, our traffic systems are less efficient because they don’t allow for communication between drivers and have to be controlled according to selfishness within the bounds of the law. Communication on the highway normally means either road rage or physical contact between cars. All this may change, however, with the advent of autonomous cars. One of the speakers mentioned that such systems could thrive off a sort of virtual pheromone trail of cars communicating with each other. Instead of having explicit lanes for each direction and drivers acting selfishly (choosing the shortest route, cutting each other off, etc.),  different patterns could emerge spontaneously as needed.


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