Scientific American reports: People are fascinated by the intelligence of animals. In fact, cave paintings dating back some 40,000 years suggest that we have long harbored keen interest in animal behavior and cognition. Part of that interest may have been practical: animals can be dangerous, they can be sources of food and clothing, and they can serve as sentries or mousers.

But, another part of that fascination is purely theoretical. Because animals resemble us in form, perhaps they also resemble us in thought. For many philosophers — including René Descartes and John Locke — granting intelligence to animals was a bridge too far. They especially deemed abstract reasoning to be uniquely human and to perfectly distinguish people from “brutes.” Why? Because animals do not speak, they must have no thoughts.

Nevertheless, undeterred by such pessimistic pronouncements, informed by Darwin’s theory of evolution, and guided by the maxim that “actions speak more loudly than words,” researchers today are fashioning powerful behavioral tests that provide nonverbal ways for animals to disclose their intelligence to us. Although animals may not use words, their behavior may serve as a suitable substitute; its study may allow us to jettison the stale convention that thought without language is impossible. [Continue reading…]