By the year 2050 one in five of the world's population will be 65 or older, a fact which presages profound medical, biological, philosophical, and political changes in the coming century. In Time of Our Lives, Tom Kirkwood draws on more than twenty years of research to make sense of the evolution of aging, to explain how aging occurs, and to answer fundamental questions like why women live longer than men. He shows that we age because our genes, evolving at a time when life was "nasty, brutish, and short," placed little priority on the long-term maintenance of our bodies. With such...