Advancements in science give hope to those who need life-saving skin grafts, replacements for failing organs – and even for those dreaming of a new head of hair. Science journalist Mary Roach joins guest host Paige Phelps to discuss the myriad of ways researchers are making progress on creating new body parts and why our immune system is the biggest hurdle of all. Her book is “Replaceable You: Adventures in Human Anatomy.”