We're moving fast. But nobody knows where we're going

Anyone who's ever looked into retirement planning must have pondered the two basic questions: at what age does one want to retire and how does one estimate her life expectancy? A few decades ago, there was nothing daunting about those questions. There'd be no reason to doubt the life expectancy statistics or consider possible variations of the retirement age, which was all but assured somewhere around 60-65. Average life expectancy heading for 100, read a sensationalist newspaper headline from 2015. But how sensational was it really, when Scientific American declared a few months ago that "aging is reversible," citing successful lab experiments on mice?