Most Americans work long hours, eat on the fly, and lead increasingly sedentary, isolated lives. Alongside this lifestyle, depression rates have skyrocketed: approximately 1 in 4 Americans will suffer from major depression at some point in their lives. Where have we gone wrong? Dr. Stephen Ilardi sheds light on our current predicament and reminds us: our bodies were never designed for the sleep-deprived, poorly nourished, frenzied pace of twenty-first century life. In fact, our genes have changed very little since the days of our hunter-gatherer ancestors and are still building, in effect, Stone Age bodies. Herein lies the key to breaking the cycle of depression.