What if science enabled us to live an extended lifespan? Well, not us, but people in the future, and perhaps not everybody in the future, at least not at first. Should we allow and encourage science to develop this capability, or should we try to prevent or inhibit it? John Davis's book New Methuselahs: The Ethics of Life Extension is a thorough exploration of these questions. He presents the arguments for and against developing this capacity, and he considers three perspectives: those of individuals who will be able to extend their lives (the Haves), individuals who will not because they can't afford to (the Have-nots), and individuals who will not extend their lives because they are opposed to doing so (the Will-nots). Davis is a philosopher, and the bulk of this book is for the cognoscenti.