"Ever so quietly," writes Charles Passy, "insurance-industry number crunchers are tossing aside the old statistical models and life tables." They're recasting tired stereotypes about the "fatal" diseases of yesteryear. They're rethinking that most ancient of questions: How long will we live? And they're coming up with what many would say is a radical answer. Call it the new death calculus: the 21st-century equation for determining human longevity. Or call it misguided guesswork, as some critics have. Either way, it's a $27 trillion question that has ramifications on both a large scale (as big governement and big business struggles to adjust their expectations of human longevity) and on a small scale (as individuals attempt to determine how much they'll need saved for retirement).