When ants are praised for their intelligence, its for their collective intelligence. By following biological programming or pheromone trails, ants build giant, well-ventilated structures or craft the most efficient possiblenetwork of paths to find food. They're treated as a set of pre-programmed instruments that follow instinct blindly.
So it's strange to learn that ants form teacher-student relationships. More experienced ants will take newbies under their wing — at least for a short time. Scientists figured this out by being the biggest imaginable jerks to whole colonies of ants. First, they painted individual ants, giving each a series of colors to distinguish each ant — and probably to get across the message "I own you" to every single ant in the bunch. Once they were able to tell one ant from another, the scientists decided to test them by ripping their homes to shreds, and seeing how the ants coped with it. First priority was to save the queen. Next priority was to get a new house and carry most of the other ants to it. Then came the time to teach other ants the way to, and around, the new home.
But how to define "teaching" in the insect world? This is one of the parts of science I like most, and that I often find more interesting than the published results of the experiments. When I hear that scientists are doing personality tests on octopuses, I'm only mildly interested in the results. I want to know how to scientifically define "personality" for non-humans. In this experiment, to get any result, researchers had to decide on how to define "teaching" for animals. They settled on the definition of teaching as 'one animal, in the presence of another animal, modifying its behavior at cost to itself in order to impart information.'