Elephants can work cooperatively if that is the only way to reach food. This kind of coordinated behaviour was once thought to be unique to our nearest primate relatives.
Joshua Plotnik of Emory University in Atlanta, Georgia, and his colleagues have previously shown that elephants seem to recognise themselves in a mirror. To test the animals' understanding of cooperation, Plotnik and his colleagues have developed an elephant version of an experiment originally run with chimps.
In this experiment, a pair of animals can bring a platform bearing food within their grasp if both simultaneously pull on the ends of a rope threaded through it. If only one pulls the rope, it unthreads from the platform, leaving the food out of reach.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The Thai elephants the researchers studied learned to tug in unison with their trunks. In experiments in which one animal was held back by up to 45 seconds, its partner would wait for it to turn up before starting to pull.
Most strikingly, in trials in which one end of the rope was curled up and out of reach, both animals backed away from the apparatus, making no attempt to pull on the rope.
Taken together, these findings suggest that the elephants had not simply learned to pull on the rope after their partner arrived at the apparatus. They seemed to understand that the cooperative task involved both animals pulling on a rope simultaneously. This puts their performance on a par with that of chimps and bonobos.
"We're excited by the results," says Plotnik. "Clearly elephants fit in the top echelon of animal intelligence."
How far that echelon extends remains to be seen.
Three years ago, pairs of rooks were shown to cooperate on a similar task, causing a stir among primatologists who had previously assumed that only great apes had the necessary combination of sociality and intelligence.
When released sequentially, however, the first rook failed to wait for its partner to turn up before pulling on its end of the string.
While that might indicate less understanding of the cooperative task, one of the researchers behind the rook study suggests that birds may simply be unable to overcome a natural impatience.
