Chimps prove cleverer than four-year-olds

Our hairy cousins have managed to reinterpret an ancient fable by solving how to reach a tasty treat by using nothing but water. How would humans do in the same test?

The peanut was tantalisingly close – but impossible to reach. If the chimp was to get its reward, it would need to engage in some serious problem-solving.

The test was simple: a 26cm glass tube was fixed to the wall. The tube was quarter-filled with water with a peanut 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, which required several visits. The rising water would then bring the peanut to the surface.

It's a similar problem to that faced by a crow in one of Aesop's fables from the 6th century BC, in which a thirsty bird uses stones to raise the water level in a jug to enable it reach the liquid and drink.

The moral of that tale was that 'necessity is the mother of invention' – meaning that when we really need to do something, we find a way of achieving it. So would the chimpanzees show themselves as clever as the bird?

The omens were not good. Scientists had already tried the test on five gorillas and none had solved the problem.

The chimps, however – based in the Ngamba Island Chimpanzee Sanctuary in Uganda and Germany's Leipzig Zoo – were much 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 of them did this enough times to successfully obtain a peanut.

'One cheeky chimp even urinated in the tube to gain his prize. Researcher Daniel Hanus said the chimp was urinating nearby after he became frustrated with spitting water into the tube. 'He then realised: "Wait a minute – if I move in that direction, that fills up the tube".'

Scientists also presented children aged four, six and 14 with the problem. The four-year-olds were outperformed by the chimps with only two out of 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.'

No accident

Dr Hanus believes the study highlights the chimps' ability to solve problems. 'You cannot explain it by trial-and-error learning. They weren't just spitting water around the room and some fell in by accident.'

They first tried to use their fingers and then tried to smash the glass. Only when these approaches failed did they use the dispenser and their spit.

Aesop's tales of problem-solving animals were not fiction after all.

You Decide

  1. Should humans regard chimps as equals?
  2. Do scientists have the right to do tests on animals?

Activities

  1. Invent a game or test to try on your pet – or a friend's pet – at home. (It's about testing their intelligence; there should be no pain involved.)
  2. Research the subject (See 'Become an expert') and write about one animal that has learned to change its behaviour in order to solve a problem.

Some People Say...

“No matter how ingenious animals are, humans still have a right to kill them.”

What do you think?

Q & A

Did the water already in the tube give a clue to the solution?
Yes. Both humans and chimpanzees were less likely to solve the task if faced with a dry tube with a peanut at the bottom. As one scientist said, a dry tube 'required thinking about water as a possible solution without having already seen it or its effect.'
So are chimps alone in being so clever?
No, in line with Aesop's story, birds can problem-solve. In a slightly different experiment in 2009, rooks had to drop stones into water to enable them to reach a floating maggot. All four of the rooks tested completed the task.
Are chimpanzees all lovely?
No, like humans, they have a dark side – as Jane Goodall discovered when she spent years living alongside them. She says that deep resentments and fights can last for years in chimp communities.

Word Watch

Aesop
(Pronounced 'Eesop') – Legend has it that he was a slave in the 6th century BC, who told stories. His existence is slightly uncertain, but over the years, many wise stories – called Aesop's fables – gathered round his name. Perhaps the best known of these is 'The tortoise and the hare.'

Subjects

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