Ants crack the secret to perfect teamwork

Weaver ants increase their individual strength as teams grow larger and offer insights that could transform robot design

To the point

• Most human and animal teams suffer from the Ringelmann effect: individuals contribute less the more the team grows
• Weaver ants avoid the Ringlemann effect as they work in a team to fold leaves into nest chambers
• A study showed that weaver ants use division of labor to not only avoid the Ringlemann effect but to achieve super efficiency

Weaver ants have solved a problem that has plagued human teams for centuries: individuals contribute less to tasks when more people join in. New research shows individual weaver ants instead get stronger as their group grows.

"These ants are super efficient in their team work,” says co-first author Daniele Carlesso from the Max Planck Institute of Animal Behavior. “As the team grows, each ant pulls more force, not less, and the team works even better.”

The longstanding problem in human teams was first published by French engineer Max Ringelmann in 1913 who measured students pulling on ropes and found that while total force increased as more people joined in, each individual's contribution actually decreased.

The study shows weaver ants form super-efficient teams in which individuals actually increase their contributions as teams grow bigger, defying the declining performance affecting human teams.

These tiny, tree-dwelling ants (Oecophylla smaragdina) found in tropical Africa, Asia and Australia, are known for their nest-building behaviors, forming living chains to roll leaves and glue them with silk from their larvae.

Daniele Carlesso worked with Madelyne Stewardson and Chris Reid from Macquarie University to measure the force different sized ant teams could apply while building nests.

The researchers set up experiments enticing weaver ant colonies to form pulling chains to move an artificial leaf connected to a force meter.

"The ants split their work into two jobs: some actively pull while others act like anchors to store that pulling force," says Stewardson.

How the ant team makes it work

Carlesso developed a theory called the 'force ratchet' to explain this mechanism.

"Ants at the back of chains stretch out their bodies to resist and store the pulling force, while ants at the front keep actively pulling," says Carlesso, who is a postdoctoral researcher at the Max Planck Institute of Animal Behavior.

David Labonte from Imperial College London, co-author on the paper, says the team found this method was key to increasing the contribution per individual as the team got bigger.

“Longer chains of ants have more grip on the ground than single ants, so they can better resist the force of the leaf pulling back,” he says.

Chris Reid says the discovery could help scientists design better robot teams. Current robots only output the same force when working in teams as when alone.

"Programming robots to adopt ant-inspired cooperative strategies could allow teams of autonomous robots to work together more efficiently," says Reid.