As the cognitive capacities of animals was touched upon under this  
heading, someone may be interested in this article in today's Guardian.

Daniele Besomi



Crows match great apes in skilful tool use
? Task revealed Caledonian crows' advanced logic
? Birds' strategy echoes early human evolution
James Randerson, science correspondent
The Guardian Friday August 17 2007
A tool-using strategy that was key to the advancement of early humans  
has been observed by scientists in a bird. "Metatool use", the  
ability to use one tool on another, is something that humans and  
great apes such as chimps and orang-utans are capable of, but with  
which monkeys struggle.

However, a study has shown that New Caledonian crows can manage this  
task easily. Researchers offered the crows a tasty morsel of meat  
that was out of reach in a box. To reach the food the birds had to  
use a long stick. But this stick was inaccessible in another box. To  
reach the long stick, the birds had to prise it out with a smaller  
stick which they could reach.

"It was surprising to find that these creatures performed at the same  
levels as the best performances by great apes on such a difficult  
problem," said Russell Gray, of the University of Auckland, New  
Zealand. "Six out of seven birds tried to get the long stick with the  
short stick at their first attempt at solving the problem."

The test revealed that the birds knew the short stick was too small  
to reach the food but that the longer stick would solve the problem.  
"They had to inhibit their normal response of trying to get the food  
directly with the short stick and realise that they could use the  
short stick to get the long stick," he said. New Caledonian crows  
previously have been shown to adapt tools for a specific job,  
something only a few primates can manage. Chimpanzees are the most  
adept ape tool-users apart from humans, using spears to hunt  
bushbabies, rocks to crack nuts and sticks to fish for termites.

Metatool use, involving making more complex and useful tools, was  
vital in our ancestors' development, say the researchers. "[It] may  
reflect the 'cognitive leap' that initiated technological evolution,"  
they write in the journal Current Biology.

The ability is conceptually hard, they argue, because the applying of  
one tool to another represents another step removed from the goal  
itself . First the animal has to realise that tools can be used on  
non-food objects, second it has to suppress the urge to go straight  
for the food itself, and third, it has to perform a sequence of  
actions in the correct order.

And, to see the solution to the problem, requires "analogical  
reasoning", the ability to see a new situation as essentially similar  
to a previous one.

To ensure the birds were not simply probing randomly with the short  
stick and getting the long stick by trial and error, the test  
involved yet another box with a stone inside. Only one bird tried  
poking the short stick into this box - and that was after she had  
already solved the problem.

http://www.guardian.co.uk/science/2007/aug/17/1