Based on studies that examine factors such as communication, learning and memory, scientists have determined that several animals possess high intelligence. Humans are the most intelligent animals, and other animals that rank high on the list are chimpanzees, dolphins and elephants. Researchers believe cephalopods, crows, squirrels, dogs, cats and pigs are also intelligent.
Intelligent animals display many behaviors that are similar to human behaviors. Chimpanzees are capable of using tools. Elephants can recognize themselves in the mirror, a skill that only great apes, dolphins and humans exhibit. Animals may also exhibit social behaviors that are normally seen only in humans. Some scientists believe a squirrel can guess another animal's intentions, such as a plan to steal its food.
When researchers classify an animal's intelligence, they sometimes look at sheer brain size. Additionally, brain structure can get an animal on the list of smart animals. A cephalopod brain has regions that are similar to human brains. These include centers for processing tactile and visual information as well as folded lobes. The octopus and squid are cephalopods.
Much of what is known about animals' intelligence has been obtained with the help of a tool commonly used by humans -- a computer. Scientists have placed animals in front of a monitor and watched them perform a variety of activities from distinguishing between familiar and novel objects to recognizing their own species.