Think of all the illustrations that you've seen about prehistoric cavemen over the years. They all had things in common. They were all long-haired, relatively unkempt, wore torn and ragged animal hides as clothing, carried a stick, hovered around a fire perhaps. Aside from those facts is one detail that sticks out like Big Bird on Sesame Street. That one detail should mean a great deal to the world today and it may just be the trick to living a healthy life. What is it?