Traffic Lessons From Army Ants

Feb. 16, 2005 -- -- Human beings could learn a thing or two about traffic from army ants. A study by researchers at Princeton University in New Jersey and Bristol University in England found that army ants create lanes of traffic that flow quickly and efficiently.

The study, published in the Proceedings of the Royal Society of London, Series B, in January 2003, says that the ants use pheromones to create paths and follow a very simple set of social rules regarding things like who has the right of way. They create three lanes of traffic -- outgoing ants in the outside two lanes and those returning to the nest in the middle.

Despite the tens of thousands of ants that may be on the move simultaneously and the fact that they're essentially blind, they're still able to maintain an even and mutually beneficial pace.

Human beings display similar behavior -- minus the pheromones -- when walking in large crowds. But all the rules seem to go out the window when we get into our cars and head into traffic.

There's No 'I' in Ant

In evolutionary terms, ants have an advantage over humans when it comes to traffic because they rely on genetically inherited behavior to keep things moving, rather than traffic laws.

Army ants "can evolve the best strategy for everyone in the population -- the one that maximizes the rate of flow along the trails," one of the study's co-authors, Iain Couzin, said in a telephone interview. "We unfortunately have to use our intelligence to create traffic rules and so forth, to try and decrease congestion within our society."

For ants, it's simple: do your job and do it right and all the ants in the colony will benefit from it.

But for humans it's a bit more complicated.

People don't always follow the rules, and rarely are they thinking about how hitting their brakes or making an unnecessary lane change could impact drivers that are far behind them.

"The wonderful thing about being an ant is that they're working together for the benefit of the colony," Couzin explained. "The problem with us humans is that we tend to be a little selfish."

Evolution

We shouldn't feel too bad though.

Couzin says that part of the challenge for humans is that we didn't evolve in the large communities and cities that we live in today. We're still figuring out the best way to live and move in groups that can easily climb into the millions.

"Ants have evolved to be within these huge societies for millions of years," said Couzin. "The individuals themselves are incredibly simple, yet working together within this large colony they can collectively solve many problems."

Human beings, on the other hand, aren't as capable of creating and agreeing on a single set of rules for everybody.

Ever been walking down a crowded hallway or sidewalk and notice how people heading in one direction move to one side and the people moving in the opposite direction move to the opposite side?

You may also notice at least a few people who don't play by these rules. They move in whatever direction they need to in order to get to their destination as quickly as possible.

Unfortunately, because those people decided to put their needs before those of the group, the entire crowd is slowed, Couzin said.

Working Together

Couzin and co-author Nigel Franks of the University of Bristol conducted the study by using complicated computer modeling software developed by Couzin, and field studies done in the rainforests of Panama.

Couzin says answers to human problems are abundant in nature, but at least one key ingredient to a successful society is cooperation.

"Ants and termites build these fantastically complicated nests with air-conditioning and all of these intricate systems," he said. "They're just following simple local rules. But by acting together with tens of thousands of other individuals, they can create amazingly complex societies."