What Doesn’t Kill Us 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, seemingly impervious to the elements. Modern humans have lost their biological link to the environment. Now we hate the cold. We suffer from auto-immune diseases. And many of us are chronically over weight. What Doesn’t Kill Us uncovers how just about anyone can reclaim our species’ evolutionary strength by reimagining how our bodies fit into the world and then slowly conditioning ourselves to unfamiliar environments.