Suresh Rattan's birth certificate reads "1955". At his age, signs of decline inevitably creep in, but Suresh doesn't feel that old. In fact, he feels twenty years younger. He can even explain why. No wonder: He does research on age and ageing at Aarhus University. Thanks to evolution, we can't imagine ourselves any older than 45. Biologically, we should just give up the ghost once we've raised a few carbon copies of ourselves. But for those of us...