When you rescale the human body in proportion to how much of the brain is concerned with each part, you end up with this: http://www.jwz.org/blog/2004/12/senso

When you rescale the human body in proportion to how much of the brain is concerned with each part, you end up with this: http://www.jwz.org/blog/2004/12/sensory-homunculus/ http://www.jwz.org/blog/2004/12/sensory-homunculus/ The hands are huge because so much of your brain is devoted to skillfully moving and precisely sensing things with your hands. Your hands are basically the focus of the human body in interacting with the environment around it. This explains how moving from buttons and sensors to a touch-sensitive experience is a major and hard-to-explain qualitative difference. It also underscores the great point made here, that we can make devices far more suited still to the primary way we're designed to interact with the world.