No insult intended to human teachers, but a research team in England says that the first clear demonstration of true teaching among other animals comes from a species without much of a brain—an ant.
A variety of animals do things that onlookers learn to copy, but biologists have a stricter definition for true teaching, explains Nigel R. Franks of the University of Bristol in England. First, teachers do a task less efficiently than they would outside the classroom. Second, pupils of a true teacher learn faster than they would by themselves.
Franks and his Bristol colleague Tom Richardson added another requirement: feedback between teacher and student.
The tiny ant, Temnothorax albipennis, from England’s southern coast, meets the criteria, Franks and Richardson report in the Jan. 12 Nature. In lab tests, the species’ teachers guided nest mates to a food source (To see a video of this behavior, click here).
“One would have expected to see teaching in chimpanzees or [some other primate], but for the first fairly strong evidence of it to come from ants is surprising and interesting,” says Bennett G. Galef Jr. of McMaster University in Hamilton, Ontario. Last year, Galef and his colleagues reported that mother rats didn’t teach their young to tell good food from bad in a lab test.
In earlier work, Franks watched ants take their nest mates to a new home. An ant that knows the new address either carries an uninformed nest mate or guides her by trotting in front of her.
Other researchers have observed such tandem running in several-dozen ant species, although an ant can run much faster alone, even when carrying a nest mate. During the guided tour, the follower ant repeatedly calls a halt and turns in loops, “as if it’s having a jolly good look around,” Franks says.
Richardson videotaped lab colonies that had a sugar solution located some 15 centimeters from their nests. During hundreds of hours of analyzing videos, he found evidence for all the true-teaching criteria. As a cost to the teacher, tandem running took four times as long to reach the sugar as traveling solo does.
For feedback, the follower ant tapped her antennae against the leader’s body to keep her moving forward. Also, if the distance between the ants shrank or stretched, both adjusted their speeds.
As evidence that the lessons helped, the researchers say that the guided newcomers found the food in two-thirds the time that they would otherwise take. In contrast, when ants of this species carry their nest mates, the novices travel upside-down and backwards, giving them little opportunity to learn a route.
For small colonies, teaching also avoids reliance on scent trails that fellow ants might not find, says Franks.