Listen in to a chilling interview with Scott Carney, author of What Doesn't Kill Us. Scott's book traces our evolutionary journey back to a time when survival depended on how well we adapted to the environment around us. Our ancestors crossed the Alps in animal skins and colonized the New World in loin cloths. They evaded predators and built civilizations with just their raw brainpower and inner grit. But things have changed and now comfort is king. Today we live in the thrall of constant climate control and exercise only when our office schedules permit. The technologies that we use to make us comfortable are so all encompassing that they sever the biological link to a changing environment. Now we hate the cold and the heat. We suffer from autoimmune diseases. And many of us are chronically overweight. Most of us don't even realize that natural variation--sweating and shivering--is actually good for us.