Walk down the average American street, and you won't pass many adults who are 100 percent human anymore--
at least not physically. Our mouths are studded with dental fillings, posts, crowns and bridgework. More than a few of us have surgical screws, pins and staples holding together fresh or old injuries. Hordes have pacemakers, artificial joints, breast implants and other internal medical devices.
This article was originally published with the title Self and Circuitry.