10/18/14 -On this hour of Radiolab: a journey to the edge of human limits. How much can you jam into a human brain? How far can you push yourself past feelings of exhaustion? We test physical endurance with a bike race that makes the Tour de France look like child’s play, and mental capacity with a mind-stretching memory competition. And we ask if robots--for better or worse--may be forging beyond the limits of human understanding.