Despite the fact that many other creatures have better eyesight than humans do, humans still have greater ability to see things that other animals cannot. Humans have the ability to see patterns, to link cause with effect, to ask the question why, and to see concepts. But why? What gives us this ability?
If we define intelligence as the ability to perceive the environment and respond appropriately to it, then each cell in our body is an intelligent being. Each cell is imbued with intent and purpose. Each one selects an appropriate response designed to favor growth and reject pain and toxins. Each cell is capable of learning, and then remembering what it learned.