Researchers at the University of Ulm, Germany, and the University of Zurich, Switzerland, spend their time putting stilts on ants.

Some of the ants get stilts, and others have part of their legs cut off. The goal was to see how the ants know how far they have walked. See, ants have a terrific sense of distance, but nobody knows exactly how they do it. Some insects use the sun's position to navigate, but that doesn't explain ants' excellent ability to know just how far they've gone.

Researchers had the ants walk out to a particular foraging trip down a tunnel. When they got there, the researchers attached little stilts to their legs.

What happened? The ants on stilts overshot the mark on the way home. The ants with shorter legs undershot the mark. See what's happening?

The ants are counting their steps. Instead of watching for visual cues the way a person would, it's as if they have a mental pedometer that says, "You have now taken seventeen steps . . . eighteen steps . . . nineteen steps . . . turn around . . . eighteen . . . seventeen . . . sixteen . . ."