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Ants teach each other to find food, researchers find
Jan. 11,
2006
Special to World Science
Some species of ants teach each other to find food, a study has found, in possibly the first documented case of teaching among non-humans.
Researchers studied the way ants of the species Temnothorax albipennis
scurry in pairs using signals that they said control the speed and route of the journey.
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Ants in a "tandem run." (Courtesy Nigel Franks and Tom
Richardson)
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The process
involves two-way communication between a teacher and a pupil, they said,
and it gradually spreads knowledge of where to find food throughout the ant colony.
A “leader” ant changes its normal behaviour for the benefit of a “pupil” who
follows, they said. The leader stops running unless the follower frequently taps it with its antennae, the researchers said.
When the gap between the pair becomes too large, each adjusts its speed to close the gap, the scientists found.
The follower ants find food quicker with the leader than when going alone, they added, suggesting that the follower learns more quickly as a result of the leader’s help. But the help comes at a cost for the leader, who normally have reached the food about four times faster if not hampered by a follower.
By the accepted definition of teaching in animal behaviour, they said, an individual is a teacher if it modifies its
behavior in the presence of an uninformed observer, at some initial cost to itself, to set an example so that the other
one can learn.
“The teacher provides information or guidance for the pupil at a rate suited to the pupil’s abilities, and the pupil signals to the teacher when parts of the ‘lesson’ have been assimilated and that the lesson may continue,” said Nigel Franks of the University of Bristol in Bristol, U.K., one of the researchers.
The paired running of the ants is called tandem running, he said.
At the start of a tandem run, the leader finds an ant who doesn’t know the route and is willing to follow, he explained. Tandem runs are rather slow because the follower frequently pauses to look round for landmarks so that it can learn the route.
Only when the follower has done this does it tap on the hind legs and abdomen of the leader to let it know the run can proceed. “If one experimentally removes the follower and taps the leader with a hair at a rate of two times per second or more, the leader will continue,” Frank said.
Tandem followers learn their lessons so well that they often become tandem leaders and in this way time-saving information flows through the ant colony, the researchers added.
The findings show big brains aren’t necessary for teaching to evolve, Frank said:
what drove this evolutionary step was instead the value of information itself. He and Tom Richardson described the research in the Jan. 12 issue of the research journal
Nature.
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