Too many cooks spoil the broth, and the same goes for ants. A study into how ants cooperate has found that the optimum strategy is for most of them not to do any work. The findings may be useful for creating large swarms of robots.

Ants create networks of narrow underground tunnels by excavating soil bit by bit as a team. To understand the strategies they use, Daniel Goldman at Georgia Tech and his colleagues placed 30 ants …