Chimps have managed to reinterpret an ancient fable by solving how to reach a tasty treat by just using water.

In the Aesop's fable 'the crow and the pitcher' a bird was able to use stones to raise the level of water in a jug to quench its thirst.

Over a series of controlled experiments, our hairy cousins were able to pluck a floating peanut out of a vertical tube after spitting water in it from a nearby dispenser.


Can't quite reach: The chimp tries to grab the floating peanut in vain

One cheeky chimp even urinated in the tube to gain his prize.

'Impressed' lead researcher Daniel Hanus, from the Max Planck Institute in Leipzig, Germany, said the chimp was urinating nearby after he became frustrated with spitting water into the tube.

'He realised: "Wait a minute, if I move in that direction, that fills up the tube",' Dr Hanus told the BBC.

'He seemed like he understood. He was like: "That's cool, this helps me".'


This time, the scientists compared gorillas, chimps and human children aged between four and eight years old.

They found that while gorillas were completely baffled by the test, chimps were more successful and older children far outperformed all their rivals.


Brain wave: The chimp holds water in his mouth and then spits it into the tube to raise the peanut

In the test, a 26cm glass tube was secured vertical to the wall. The tube was quarter filled with water and a shelled peanut was placed floating inside. A water dispenser was placed a metre away.

The only way to reach the peanut would be to take water from the dispenser and fill the tube during several visits.

The team found that none of the five gorillas was able to complete the task.

However, the chimps based in the Ngamba Island Chimpanzee Sanctuary, in Uganda, and Germany's Leipzig Zoo were more successful.

Out of 43 chimps, 14 worked out that they needed to take the water in their mouths and spit it into the tube, and seven did this enough times to successfully obtain a peanut.

The chimp that urinated into the tube was successful and still ate the ammonia-rich peanut.

The children subjects were given a watering can to fill the tube rather than relying on spitting.


Success: The chimp enjoys his peanut prize

The four-year-olds were outperformed by the chimps with only two out 24 solving the problem.

However, 10 out of 24 six-year-olds and 14 out of 24 eight-year-olds were successful.

Dr Hanus said: 'Even the older children found it hard. It was interesting and impressive to see how difficult it was for them.'

Participants from all three species were less likely to solve the task if faced with a dry tube with a peanut at the bottom.

Scientists said this was because it was a more demanding task.

Writing in the Plos ONE journal, they explained: 'It requires thinking about water as a possible solution without having already seen it or its effect.'