Radiolab Presents: Viscera

For hundreds of years, we have been trying to replace parts of ourselves, from our beating hearts and other organs to the skin on our bodies to the hair on our heads. Nearly every part.

In the latest Viscera, ER Doc Avir Mitra and Senior Correspondent Molly Webster take us into the wild, rapidly evolving world of transplants. Then we’ll kick it with New York Times bestselling science writer Mary Roach (Stiff and Ruff, Replaceable You), who spent the last couple of years traveling all over, from Sichuan Province in China to Tbilisi, Georgia, to Massachusetts General Hospital, to understand just how far we’ve come, and how far we’ll go, to replace our parts.

And Avir talks with his dear friend, Alin Gragossian, about one of the scariest days of both of their lives. And we ask: After all our years of trying, how close are we to convincing our bodies to accept what isn’t us?

Mary Roach

Bestselling Author

Mary Roach is the author of the New York Times bestsellers STIFF, SPOOK, BONK, GULP, GRUNT, FUZZ, and PACKING FOR MARS. Her new book, REPLACEABLE YOU: Adventures in Human Anatomy, debuts in September 2025. Mary has written for National Geographic, Wired, and The New York Times Magazine, among others, and her TED talk made the TED 20 Most Watched list. She has been a guest editor for Best American Science and Nature Writing, a finalist for the Royal Society's Winton Prize, and a winner of the American Engineering Societies' journalism award, in a category for which, let's be honest, she was the sole entrant.

Molly Webster

Molly Webster is the Senior Correspondent at Radiolab, the award-winning radio and podcast program.

At Radiolab, she reports and hosts special series and live events. Her ability to comprehend and totally immerse herself in complicated issues has helped Radiolab investigate international surrogacy, the price of a human life, and one very special jar. She has adapted her audio and written work for the stage, performing in theaters from BAM to TED to Hollywood.

Molly is the author of the children’s book, Little Black Hole, about one very lonely black hole.

Dr. Avir Mitra

Dr. Avir Mitra, emergency medicine physician, educator, and storyteller associate professor of emergency medicine at NYU Grossman School of Medicine.