Their intellectual abilities struck mankind for quite long time. They can solve their current problems, learn sign language and use it to communicate with people. They are superior to humans in tests for memorizing numbers, and you can even learn them to use the computer to solve simple math problems.
They have a complex language, they can communicate with each other and respond to the behavior of the team. They were used as messengers during the wars, and the bark and the frontal lobes of their brains 40% bigger than people have.
Elephants are on this list solely because of their memory. Most of the elephants clean food before eating it, and mourn the death of a member of their flock. They can remember exactly where the wells are located.
They are sly: in particular, they collect the nuts, and then bring them on the way to passing car that can crush solid shell of nuts. To pick up their dinner and not to get under the wheels they are like educated pedestrians, wait for the green light. They use certain sounds for communication, and still love to make fun of each other.