A cunning horse and a "speaking" gorilla: what were the cleverest animals

What animals it is possible to call the cleverest surely? Certainly, anthropoids, dolphins, dogs. Quite good mental abilities at octopuses. And here among birds superiority belongs to crows. They can be trained to solve a puzzle, to use tools and to execute difficult commands. For example, to bring red cube, and since five years even to teach separate words and to answer some questions. In general, the history knows many surprising examples of communication of the person with animals. Who managed to teach a horse to consider? On what the brain of a pigeon is capable? And than the cruel ended...