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Ants Have Teacher-Pupil Relations, Researchers Report

John Roach
for National Geographic News
January 11, 2006
 
When you were younger, did a family member ever show you how to
find the local grocery store? Members of the ant species
Temnothorax albipennis have a similar family tradition,
according to a new study.

The finding may be the first known example of a teacher-pupil relationship in a nonhuman animal, according to Nigel Franks, a biologist at the University of Bristol in the United Kingdom.

"While it's well known that animals will mimic each other, so one animal is learning from another … there's sort of a two-way street in teaching that defines true teaching," he said.

For example, even though your guide could get to the store faster without you in tow, he or she slowly and patiently taught you the way so that you could one day make the trip on your own.

In a similar manner, ants in a T. albipennis colony use a technique known as tandem running to teach each other how to get from the nest to a food stash. Franks and colleague Tom Richardson report the find in tomorrow's issue of the science journal Nature.

In a tandem run, the lead ant only continues forward when frequently tapped on its legs and abdomen by the following ant's antennae. When a gap appears between the two, each adjusts its speed to close it.

The researchers show that the lead ant in the tandem pair could reach the food stash four times faster when not slowed by a follower.

But the follower ant finds the food faster than when searching alone and is ultimately able to quickly run solo errands. The process likely increases the fitness of the entire ant colony, the researchers say, by making the ants more efficient.

Teaching Defined

According to Franks, the lead ant's sacrifice is a hallmark of teaching that until now has been shown only in humans.

He and Richardson write that "an individual is a teacher if it modifies its behavior in the presence of a naïve observer, at some initial cost to itself, in order to set an example so that the other individual can learn more quickly."

In addition, the Bristol researchers say that teaching involves a two-way relationship between the teacher and pupil.

In humans, for example, professors ask their students questions to make sure they understand the subject matter. At the same time the professors encourage questions from their pupils, Franks explained.

Franks and Richardson suggest the tandem-running ants meet these criteria—the lead ant moves at a slower pace to set an example, and the pair only moves forward when they are in contact with each other.

Marc Hauser is the director of the Cognitive Evolution Lab at Harvard University in Cambridge, Massachusetts. In 1992, he and University of California at Davis ecologist Tim Caro devised the definition for teaching Franks and Richardson cite in their study.

Hauser said in an email that the University of Bristol researchers present a "very interesting observation" about ant behavior.

But, he said, "I don't think it shows teaching in the way Caro and I originally formulated."

According to Hauser, the follower ant gains new information, not a new skill, via the tandem run.

"If the transfer of information from a knowledgeable individual to an ignorant one is teaching, then almost all of communication is teaching," he said.

Such a definition, Hauser added, would "defeat what is interesting about teaching, which is that an animal lacking in some skill acquires one, or acquires it faster, due to the costly investment of demonstration by [an] instructor."

Franks and Richardson say the ants acquire knowledge about finding a food source, as well as gaining more general knowledge about their environment.

For example, on the return trip the follower ant often takes a different, more direct path than the one it was taught.

"The follower learns more general knowledge about the foraging environment and then it computes its own return path. That's a fabulous thing," Franks said.

According to Franks, the tandem-running behavior suggests that teaching can "evolve in rather small creatures with very small brains." The finding challenges a notion that a big brain is a prerequisite for two-way teaching.

"It suggests that if the information is particularly valuable, then evolution can come up with rules of behavior to allow teaching to occur," he said.

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