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Us humans are pretty unique animals in many ways. I mean, we wear underpants, for one. But the more we learn about other species, the more we realize a lot of the qualities that we thought made us unique actually aren't unique to us, like we're not alone in our abilities to make tools, express emotions, or even develop distinct cultures.

And we now know that despite what many scientists once thought, we're also not alone in our ability to teach. Oddly enough though, the animal that first revealed this wasn't another primate or even a mammal. It was an ant!

Now, to be clear, we know that lots of animals learn. In many cases, individual animals observe others' behavior to pick up important information like what to eat or what to fear.

And scientists have observed this in a wide range of species, from chimpanzees to rats to octopuses. But it's harder to show that any given animal is actually teaching. Researchers have set up criteria for how to tell.

They say that teaching has to be active, not passive. In other words, if an animal is just living its life and another individual happens to learn something from it, it's not teaching.

Teaching also has to come at some cost to the teacher, like an animal has to make some extra effort that's specifically for the sake of transferring knowledge to be considered a teacher.

Third, the teacher has to set an example for their pupils.

And fourth, this should lead to faster learning. If an animal could learn just as quickly by fumbling around on its own, the behavior doesn't count as teaching.

Some researchers have also suggested that teaching has to involve some sort of back-and-forth interaction between teacher and student.

So it's a pretty high bar to clear, and for a long time scientists thought that human teachers were the only ones that met all these criteria.

But in a 2006 study, the rock ant, of all things, proved them wrong. Previously, researchers studying these ants had noticed that they had an unusual way of recruiting their members to a specific location, such as a new food source or a nesting site.

Unlike many ants, which lay down scent trails for other members of the colony to follow, rock ants perform what are called "tandem runs."

Basically, an ant that already knows the way personally leads a learner ant to a given location. In other words, it kind of looked like these ants were teaching each other the route.

But scientists weren't sure if the ants in the lead were truly teaching or just being followed, so in the 2006 study one team of researchers looked into it.

In their lab, they filmed ants as they traveled between their nest and a new food source. Then they observed how ants that already knew the route interacted with those that hadn't learned it yet, and they found that the leader ants weren't just being followed.

They would only move forward as long as their followers were tapping their legs and abdomen with their antennae. If they didn't get this physical feedback, they would stop, so they were actively leading.

On top of that, the teachers were definitely making a sacrifice in the form of time. They kept having to pause as the student learned landmarks along the way, which made their journey four times slower.

The study authors were also able to show that the leading ant successfully set an example for its followers, and as a result, learner ants repeatedly found the new food site more quickly from tandem runs than when they were left to search for it alone.

Finally, the authors even observed back-and-forth feedback between the student and teacher. If the leader got too far ahead, it would not only slow down but the follower would speed up, showing that they were responding to feedback from each other.

All this evidence implied that these tandem runners were truly teaching. But even though scientists agreed that teaching was happening, some researchers wondered if rock ants were still relying on scent trails from their teacher to support their learning.

In other words, maybe these ants weren't just relying on the teacher to actively teach them the route. After all, many ant species do lay scent trails down for others to follow.

So to rule out that possibility, the authors of a 2022 study set up an experiment where the learner ants followed a robot teacher instead of another ant.

The researchers did use a pheromone marker on the robot itself to trick ants into thinking it was a member of their colony so they would follow it, but they used airborne pheromones that never touched down on the ground, so learner ants could only follow the robot itself, not some trail it left behind.

And they did follow it! Even following a robot, they learned routes much faster than ants with no teacher, which makes the rock ant the first non-human species to have its teaching ability documented scientifically.

But it's definitely not the only one! Since the discovery of these little teachers in 2006, scientists have found that numerous species teach, including meerkats, dolphins, and birds.

The fact that this ability shows up in such different species suggests that it's actually pretty common among animals, even those without big, advanced brains. It's just kind of hard to prove.

And it highlights the fact that our human biases influence our perception of the world in so many ways. But by studying these teachers from other parts of the animal kingdom, we can learn about how this ability evolved and what we humans have in common with our fellow animals.

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