Death is inevitable, we're told. Everything wears out, and that includes our bodies. So aging is a matter of wearing out. The conventional wisdom is that we get old - and eventually die - simply because our bodies become too worn to function as they should. But what if the conventional wisdom is completely wrong? There is growing evidence that senescence and death are inventions, evolutionary creations that serve a specific and previously unsuspected purpose. The evidence says that they are in fact weapons developed in the course of our struggle to defeat our parasites. The new view is that...