Go to the BBC webpage to see footage of the experiment - Thanks to Geraldine F for the link!
By VICTORIA GILL
Footage of an oversized experiment has revealed that elephants understand when they need help from a partner.
In the test, two animals had to work together - each pulling on a rope in order to tug a platform towards them.
Elephants' apparent grasp of the need to co-operate shows, scientists say, that they belong in an "elite group" of intelligent, socially complex animals.
Researchers from the University of Cambridge built the apparatus, which was originally designed for chimps.The team published their findings in Proceedings of the National Academy of Sciences.
Study leader Dr Joshua Plotnik from the University of Cambridge said it was exciting to find a way to study elephant behaviour in such detail.
"It's so hard to work with elephants because of their size," he said.
"We see them doing amazing things in the wild, but we can see from this that they're definitely co-operating."
The Asian elephants (Elephas maximus) involved in the study had already been taught that pulling on a rope brought a platform towards them, and a food reward on that platform within reach.
But this apparatus, set up at the Thai Elephant Conservation Center in Lampang province, presented them with a new twist on that simple task.
One rope was threaded all the way around a platform - like a belt through belt loops - so if one end was tugged, the rope simply slipped out and the platform did not budge.
But if two elephants each took an end of the rope and pulled, the platform moved and that could claim their treats.
"When we released one elephant before the other, they quickly learned to wait for their partner before they pulled the rope," Dr Plotnik told BBC News.
"They learnt that rule [to wait for the other elephant to arrive] quicker than chimps doing the same task.
And one elephant - the youngest in the study - quickly learned that it did not have to do any pulling to get a treat.
"She could just put her foot on the rope, so her partner had to do all the work," said Dr Plotnik.
Many scientists, photographers and film-makers have documented remarkable behaviour by wild elephants, including "targeted helping" of other elephants that become stuck in mud.
There have even been reports of elephants appearing to mourn their dead.
"As humans, we like to show that we're unique," said Dr Plotnik, "but we're repeatedly shot down.
"One thing that remains is our language. But amazingly complex behaviours - culture, tool use, social interaction - we see all of this in the animal kingdom."
As well as adding to our knowledge of the evolution of social complexity, Dr Plotnik hopes that his findings will help with the conservation of these endangered animals.
"The more we can understand about their intelligence, the better we can develop solutions to things like human-elephant conflict," he explained.
"So when the animals are raiding crops, we need to think of solutions that are based on the reasons why, and that benefit elephants as well as people."
Plotnike JM, Lair R, Suphachoksahaknub W, de Waal FBM (2011) Elephants know when they need a helping trunk in a cooperative task. PNAS doi: 10.1073/pnas.1101765108
Elephants are widely assumed to be among the most cognitively advanced animals, even though systematic evidence is lacking. This void in knowledge is mainly due to the danger and difficulty of submitting the largest land animal to behavioral experiments. In an attempt to change this situation, a classical 1930s cooperation paradigm commonly tested on monkeys and apes was modified by using a procedure originally designed for chimpanzees (Pan troglodytes) to measure the reactions of Asian elephants (Elephas maximus). This paradigm explores the cognition underlying coordination toward a shared goal. What do animals know or learn about the benefits of cooperation? Can they learn critical elements of a partner's role in cooperation? Whereas observations in nature suggest such understanding in nonhuman primates, experimental results have been mixed, and little evidence exists with regards to nonprimates. Here, we show that elephants can learn to coordinate with a partner in a task requiring two individuals to simultaneously pull two ends of the same rope to obtain a reward. Not only did the elephants act together, they inhibited the pulling response for up to 45 s if the arrival of a partner was delayed. They also grasped that there was no point to pulling if the partner lacked access to the rope. Such results have been interpreted as demonstrating an understanding of cooperation. Through convergent evolution, elephants may have reached a cooperative skill level on a par with that of chimpanzees.