Studying army ants for a living carries certain occupational risks.
“They are very aggressive,” says Isabella Muratore of the New Jersey Institute of Technology. “They have venom, so they will sting and bite you. It’s not that bad. It’s just that you usually get bitten by hundreds of them at once.”
Ants are fierce predators, devouring other insects – sometimes even frogs, lizards and birds. But what is even more remarkable about them is their architectural prowess.
Muratore studied how army ants build bridges by connecting their bodies, which could give scientists insight into controlling swarms of robots. She presented her work at a meeting of the Entomological Society of America in early November.
Commonly found in Central America, South America, and Africa, ants roam the forest floor in long lines in search of food.
When they encounter obstacles – like a gap between leaves or branches – they build a bridge, connecting them like a monkey barrel.
“Workers will chain themselves together to get through that gap, and then other workers will walk over it,” Muratore told News. “Basically, they create shortcuts to make it easier for other ants or just to allow them to get through something they couldn’t otherwise.”
Instead of going around an obstacle using a complicated path, she says, ants make their hunting more efficient, allowing them to collect more food.
But building bridges comes at a cost to the colony: the ants responsible for supporting the bridge are not available to hunt.
Although they individually have small brains, ants collectively weigh the costs and benefits of a bridge, Muratore said.
Muratore studied ants’ decision-making by deliberately placing obstacles in their path as they navigated the forest. She filmed them, then analyzed the ant traffic.
She says ants build bridges where they get the greatest benefit for the fewest bodies – and she has identified a sweet spot where the gap is large enough to warrant building a bridge, but not so large that It takes too many ants to do it. . She also discovered that a series of bridges can influence the amount of power ants are willing to invest in each individual bridge.
“Just like people, we’re not just building a bridge, we have to decide, ‘What is this whole road going to look like despite lots of different obstacles?’” says David Hu, an engineering professor at the Georgia Institute of Technology. , who extensively studied how fire ants build rafts to survive floods.
Hu says this type of research sheds new light on the collective intelligence of army ants. He compares individual ants to “neurons in a large moving brain,” with no individual ant deciding where to build bridges.
Ants’ collective decision-making also has implications for human technology. Engineers have already applied swarm behaviors learned from ant research to creating algorithms for self-assembling robots.
“For a long time, the big challenge in robotics was taking a bucket of robot parts and throwing it away so that robot would be able to put itself back together and solve bigger problems,” Hu said.
“The ants are sort of proof that such a robot would actually be able to survive and have many interesting problems to solve in the real world,” Hu said. “(Ants are) really capable of solving these problems with very, very little gray matter.”