Replaceable You: Adventures in Human Anatomy by Mary RoachThe body is the most complex machine in the world, and the only one for which you cannot get a replacement part from the manufacturer. For centuries, medicine has reached for what’s available—sculpting noses from brass, borrowing skin from frogs and hearts from pigs, crafting eye parts from jet canopies and breasts from petroleum by-products. Today we’re attempting to grow body parts from scratch using stem cells and 3D printers. How are we doing? Are we there yet?  In Replaceable You, Mary Roach explores the remarkable advances and difficult questions prompted by the human body’s failings. When and how does a person decide they’d be better off with a prosthetic than their existing limb?