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 criteriathe 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.
Free E-Mail News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES