What Ants Can Teach Us About Traffic Jams

You have to admire the grace of ants on the move. No matter how many of them are streaming toward their destination, there's never a hold up. No fender benders. And, unlike humans, they know how to pull off a proper lane merge.

There are many fascinating facets of ant life, but none may pack a more practical lesson for us than their gift for avoiding traffic jams.

A new research paper published this week in the journal eLife reveals how ants keep traffic flowing by changing their behavior to meet changing conditions.

If traffic is at a trickle, for instance, ants will space themselves out and behave more individualistically. But when it's bumper-to-bumper — or in this case, antennae-to-abdomen — they coalesce into a single stream that just keeps flowing.

For their experiments, researchers from the University of Toulouse and the University of Arizona focused on Argentine ants, critters that frequently move from colony to colony depending on the proximity of food sources.

As Annelee Newitz writes in Ars Technica, "Their ability to move quickly in large groups is what helped them swarm on my cats' food so fast — and it's why they were able to pack up their eggs and flee the flood in my backyard like well-trained disaster workers."

Tapping into the Argentine ants' knack for fast commutes, the researchers built bridges connecting their colonies. The bridges varied in width from a fifth to three-quarters of an inch. The colonies, too, were of different sizes, ranging from 400 to more than 25,000 ants.

Essentially, researchers built a new infrastructure system for the ants, connecting their biggest cities to the smallest hamlets. Then they sat back and monitored the traffic.

And surprise, surprise, even when those narrower bridges reached near-capacity, there were no 20-ant pile-ups. Indeed, there was nary a fender-bender.

Traffic remained steady regardless of how overburdened the infrastructure because they were able to adjust to the ebb and flow of road conditions. At some point, when the bridges got really busy, ants moved not so much as individuals but rather like water flowing in an ever-constant stream.

"When density on the trail increases, ants seemed to be able to assess crowding locally and adjusted their speed accordingly to avoid any interruption of traffic flow," the authors note in a news release. "Moreover, ants restrained themselves from entering a crowded path and ensured that the capacity of the bridge [the maximum value of the flow allowed by the bridge width] was never exceeded."

The lesson for humans? The traffic conundrum — one of modern life's seemingly unsolvable puzzles — may lie in our inability to adjust our driving habits for the good of the whole. You've probably noticed it on your own commute to work. Driving is fun when there are few cars on the road — a lane-change here, a little acceleration there. Then traffic slows to a crawl. And yet, some impatient driver still acts like he's alone on the road, tailgating and constantly jockeying between lanes. It doesn't buy that driver any more time, but instead further entangles traffic.

Ants, being the ultimate collectivists, don't have time for yahoos.

"Traffic jams are ubiquitous in human society where individuals are pursuing their own personal objectives," the authors write. "In contrast, ants share a common goal: the survival of the colony, thus they are expected to act cooperatively to optimize food return."

The research also suggests that infrastructure projects, like the ever-widening of highways, may never free us from the plague of traffic jams. As long as we motor along with our own agendas, no matter how many other people are on the road, we'll always end up in a traffic snarl.

Indeed, less space may actually be a good thing. It leaves less room for individual choice and forces us to take a page from the driving manual of ants.