Published: July 2007
The Genius of Swarms
A single ant or bee isn't smart, but their colonies are. The study of swarm intelligence is providing insights that can help humans
manage complex systems, from truck routing to military robots.
By Peter Miller
I used to think ants knew what they were doing. The ones marching across my kitchen counter looked so confident, I just figured they had a plan, knew
where they were going and what needed to be done. How else could ants organize highways, build elaborate nests, stage epic raids, and do all the other things
Turns out I was wrong. Ants aren't clever little engineers, architects, or warriors after all—at least not as individuals. When it comes to deciding what to do
next, most ants don't have a clue. "If you watch an ant try to accomplish something, you'll be impressed by how inept it is," says Deborah M. Gordon, a
biologist at Stanford University.
How do we explain, then, the success of Earth's 12,000 or so known ant species? They must have learned something in 140 million years.
"Ants aren't smart," Gordon says. "Ant colonies are." A colony can solve problems unthinkable for individual ants, such as finding the shortest path to the
best food source, allocating workers to different tasks, or defending a territory from neighbors. As individuals, ants might be tiny dummies, but as colonies
they respond quickly and effectively to their environment. They do it with something called swarm intelligence.
Where this intelligence comes from raises a fundamental question in nature: How do the simple actions of individuals add up to the complex behavior of a
group? How do hundreds of honeybees make a critical decision about their hive if many of them disagree? What enables a school of herring to coordinate its
movements so precisely it can change direction in a flash, like a single, silvery organism? The collective abilities of such animals—none of which grasps the
big picture, but each of which contributes to the group's success—seem miraculous even to the biologists who know them best. Yet during the past few
decades, researchers have come up with intriguing insights.
One key to an ant colony, for example, is that no one's in charge. No generals command ant warriors. No managers boss ant workers. The queen plays no role
except to lay eggs. Even with half a million ants, a colony functions just fine with no management at all—at least none that we would recognize. It relies
instead upon countless interactions between individual ants, each of which is following simple rules of thumb. Scientists describe such a system as
Consider the problem of job allocation. In the Arizona desert where Deborah Gordon studies red harvester ants
calculates each morning how many workers to send out foraging for food. The number can change, depending on conditions. Have foragers recently
discovered a bonanza of tasty seeds? More ants may be needed to haul the bounty home. Was the nest damaged by a storm last night? Additional