Being part of a bridge might not be as demanding for an individual ant as it might seem Alexander Wild

BARRO Colorado Island is tiny and sits in the middle of the Panama Canal. Here, below the forest dome, a diminutive predator scuttles over dead leaves and along narrow branches. Nearly blind, this Eciton army ant follows a trail of chemical signals laid down by her sisters. She pushes forward, relentlessly, in search of prey. Whatever she finds, she’ll bring back to the nest to share with her colony.

But then she stops. The ground has dropped away in front of her. There is no scent trail, just empty space. Other members of the colony that were following begin to climb over her. Now, instead of walking in a line, they grip hold of one another using hooks on their feet, adding body after body to build an impromptu bridge. More and more join in, until they traverse the gap. And there they remain until the entire foraging party, numbering hundreds, has crossed. Then, as suddenly as it came into being, the bridge disperses, and the ants continue on their way.

How do these creatures achieve such an impressive feat of coordination with very limited brainpower and no overview of the situation? That’s the question a group of researchers working on Barro Colorado Island set out to answer. Their efforts have revealed how ants use simple cues to organise themselves into complex living structures. It’s a wonder of nature, and it could offer insights for engineers, mathematicians and robot designers. What’s more, it might even shed some light on our …