Depression rates have skyrocketed: approximately one in four Americans will suffer from major depression at some point in their lives, according to Ilardi, associate professor psychology at the University of Kansas. Inspired by the extraordinary resilience of aboriginal groups like the Kalluli of Papua New Guinea who rarely suffer from depression, Ilardi's book prescribes an easy-to-follow, clinically proven program that harks back to what our bodies were originally made for — and need.