A press release from the University of Cambridge has announced a forthcoming paper about the latest and possibly greatest stars of non-human animal intelligence, rooks, and their ability to make tools spontaneously without have learned their use from other birds or from humans. The rooks, birds related to ravens and crows, showed themselves the equal of better known animal tool users, the chimpanzees and their distant cousins, the New Caledonian crows.
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In a series of experiments, the rooks quickly learnt to drop a stone to collapse a platform and acquire a piece of food, and subsequently showed the ability to choose the right size and shape of stone without any training.

Not only could they use stones to solve the task, but they were flexible in their tool choice, using and modifying sticks to achieve the same goal. When the correct tool was out of reach, they used another tool to get it, demonstrating the ability to use tools sequentially. In further tests, the rooks were able to use a hook tool to get food out of a different tube and even creatively bent a straight piece of wire to make the hook to reach the food.

News of non-human ingenuity rarely surprises me. I was the editor of John T. Bonner's classic synthesis, Evolution of Culture in Animals, still in print and an excellent introduction to the topic after 25 years of further research.

Results like this open up a new question. Since animals are more capable of using technology than we had realized, why don't they do so more often? They have mental abilities not readily observed in the wild but in some cases superior to humans' -- like chimps' recall of a series of random digits presented on a computer screen. Some scientists speculate that we had to lose some mental abilities (immediate memory) to acquire the capacity for language. As the press release notes, "Necessity is the mother of invention for clever birds." In the wild, they didn't need tools; food was all around them.

This Op-Ed by the materials science and engineering professor Stephen L. Sass, shows how much the technology that helped us bring out the brains in these birds, and spread the news about them, was itself the result of new constraints; a shortage of tin (for making bronze) in the eastern Mediterranean was the incentive that led to the Iron Age.

(The actual paper on Rooks was not yet available on the National Academy of Science site when this was posted.)