Of birdbaths and birdbrains

A crow sits on a fence overlooking the lake in St James's Park, London.
Image caption Corvids, like this crow, are popularly noted for their intelligence

Crows - as any child familiar with Aesop's Fables can tell you - are very smart birds. But are they smarter than children?

According to Aesop "A crow, half-dead with thirst, came upon a pitcher of water..." to cut a long story short, the crow realised that by dropping a succession of stones into the pitcher it could raise the level of the water and "...quench his thirst and save his life".

And the moral of the story? Little by little does the trick.

It's a nice story, and - even better - it's true. Researchers at the University of Cambridge showed some time ago that rooks (a member of the crow family) can not only solve the puzzle, but can distinguish between useful pebbles and pieces of cork that will merely bob about on the surface.

So where do the children come in? Experimental psychologist Lucy Cheke wanted to know a bit more about how the birds were doing it, what it says about the way they construct a mental picture of the world around them, and how that differs from the way children learn about cause-and-effect.

"We wanted to find out what, and how, the birds were learning. Was it intuition, simple trial and error, or did the birds understand something of the laws of physics?"

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Media captionLucy Cheke explains how the experiments on animal intelligence work

Crucially, Lucy Cheke wanted to know if the birds were simply solving the logical problem, or whether - like children - they had a wider understanding of the possible. Could they learn about new cause-and-effect relationships?

To find out she devised this cunning counter-intuitive apparatus. Unlike Aesop's pitcher, when you drop stones into one of the tubes the water level remains the same, but rises in another. It doesn't make sense, but if all you want is the water, that shouldn't matter - simply drop in the stones and collect your prize from the wrong tube.

No matter how many times they tried the birds - in this case Eurasian Jays - just couldn't get it. The children, on the other hand, seemed to accept the illogical consequences of their actions with relative ease.

Image caption John, Lucy and Justin try the experiment

"The children were able to learn what to do to get the reward even though the chain of events was apparently impossible," she says. "They were able to ignore the fact that it shouldn't be happening and concentrate on the fact that it was. The birds, however, found it much harder because they were put off by the fact that it shouldn't be happening."

So what have we learnt? Lucy Cheke believes the children's success, and the birds' failure, tells us something about the difference between the way that birds and children think.

"It makes sense because it is a child's job to learn about new cause-and-effect relationships without being limited by ideas about what is or is not possible."

It tells us something about the plasticity of children's brains. This openness to new ideas helps to explain why children believe in magic, or can become convinced that if you smile at a traffic light it turns green. Over time, incorrect assumptions about the world are whittled away by trial and error. It may also help to explain why animals with the longest childhoods are typically the most intelligent.

And just in case you're wondering if John is still in the studio dropping stones into the tube and trying to work out why he can't get a drink of water... you might think so, but I couldn't possibly comment.