It is quite puzzling, therefore, why the field of animal cognition has such a long history of claims about the absence of capacities based on just a few strolls through the forest.

WSJ: The Brains of the Animal Kingdom

However, the second study, carried out by Dr Bugnyar when he was working at the University of Austria, and published last month in Animal Cognition, suggests that ravens may have mastered the art of deception too.

ECONOMIST: Now, it seems, even the bird-brained have theories of mind

In the 1990s, Russian chemist Sergey Bachurin showed it had potential for improving cognition in a variety of lab-animal tests.

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