Elephants quickly learn to work together to solve problems, according to researchers.
The giant mammals are socially complex, explained lead researcher Joshua Plotnik, of Cambridge University.
"They help others in distress," he said. "They seem in some ways emotionally attached to each other, so you would expect there would be some level of co-operation." However, he added: "I was surprised how quickly they learned."
The elephants caught on as quickly as chimpanzees, elevating themselves to such heady company as great apes, dolphins and crows, according to Mr Plotnik, of the university's department of experimental psychology.
Tests conducted in Thailand involved food rewards placed on a platform on the ground connected to a rope. The elephants were behind a fence. To get the food, the elephants had to pull the two ends of the rope at the same time to drag the platform under the fence.
Six pairs of elephants were tested 40 times over two days and every pair figured it out, succeeding on at least eight of the last 10 trials.
Then the scientists tried releasing the elephants into the test area separately, up to 45 seconds apart. The elephants quickly learned to wait for their partners, with a success rate of between 88 and 97% for various pairs on the second day.
However, one young elephant had what the researchers termed an "unconventional" solution to the problem. As Mr Plotnik and co-authors explained, the elephant firmly put one foot on the end of her rope, "forcing her partner to do all the work to retrieve the table".
In another experiment, the researchers left only one end of the rope within reach of the elephants, with the other end coiled on the table. The elephants did not bother to pull the rope, seeming to recognise that it would not work if their partner could not pull the other end.
Adam Stone, elephant programme manager at Zoo Atlanta, said it was significant that the elephants learned quickly. It was long thought that learning and co-operation were limited to primates, and "it's interesting to see that these other species are on the ball," Mr Stone said.