Podcast Summary: Short Wave – How Replaceable Are You?

Host: Regina Barber (NPR)
Guest: Mary Roach, nonfiction author (book: Replaceable You)
Date: December 10, 2025
Duration: ~15 minutes

Episode Overview

In this lively and science-filled episode of Short Wave, host Regina Barber talks with Mary Roach about the remarkable, bizarre, and sometimes funny science behind replacing human body parts. Drawing from Roach’s book, Replaceable You, the episode delves into medical advances—from artificial tears and burn treatments to full organ “remakes” using unlikely body parts. The conversation explores the limitations of current technology, the creativity of surgeons, and how close (or far) we are from becoming real-life cyborgs.

Key Discussion Points & Insights

The Challenge of Replacement: Are We Truly Replaceable?

• Imperfection in Artificial Replacements
  • Mary Roach shares a surprising insight about our inability to perfectly replicate even something as “simple” as tears.
    • “So artificial tears, he’s like, yeah, they'll help for an hour or two, but they kind of wash away the good stuff. So we don’t even have, we can’t really even replace tears.” (Mary Roach, 00:53)
• Regina’s Cyborg Dreams Dashed... for Now:
  • Jokingly laments the limitations: “So my cyborg dreams may not become a reality just yet, but science has still made huge progress when it comes to fixing the human body when it fails.” (Regina Barber, 01:39)

Advances in Burn Treatments

• Traditional vs. Modern Skin Grafting
  • Third-degree burns devastate the body's own ability to heal.
    • “Third degree burns are really tough because the cells that would regenerate from below… those are destroyed. So the body tries to heal by contracting, kind of pulling like a drawstring.” (Mary Roach, 01:56)
  • Modern techniques can culture a patient’s skin off-site or use “spray-on” skin, enabling faster and less painful recovery.
    • “There are ways now to culture the person’s skin off site… you can take a biopsy, and they can grow out these very thin layers of the person’s own skin. There’s spray on skin.” (Mary Roach, 01:56)

Can We Replace the Lungs? The Story of the Iron Lung

[Segment starts at 04:07]

• Mary Roach details the history of the iron lung, which served as a life-saving device during the polio epidemics.

• Comparison: Iron Lung vs. Modern Ventilators

  • Iron lungs use negative pressure (imitating natural breathing), while mechanical ventilators force air into lungs (positive pressure).
    • “The iron lung works the same way [as natural breathing]. It’s called negative pressure ventilation.” (Mary Roach, 04:40)
  • Iron lungs allow for more “natural” breathing, but with limitations—no control over inhale/exhale, and a physically uncomfortable tight seal around the neck.
    • “Your breathing feels the way your breathing does when you're not in an iron lung, except that you have absolutely no control over when you're going to inhale and when you're going to exhale… you have this thing around it... like somebody is choking you.” (Mary Roach, 05:28, 06:20)

• Personal Anecdote:

  • Roach attempted to sleep overnight in an iron lung.
    • “I lasted about seven minutes.” (Mary Roach, 06:51)

• Pros and Cons of Modern Mechanized Breathing

  • Ventilators require intubation (can’t speak or swallow), have risks like lower-lung issues, cognitive decline, and muscle atrophy if used long-term.
    • “If you’re sedated on positive pressure for days and weeks, then you start to get sometimes cognitive issues. Muscle deterioration… you don’t want to be on a positive pressure ventilator for extended period of time.” (Mary Roach, 07:11, 07:59)

Remaking Organs: The Vagina Dialogue

[Segment starts at 08:35]

• Surgeons sometimes use sections of the colon to construct vaginas when the “usual” methods aren’t possible.
  • “The colon… it makes a lot of sense. You know, it’s tubular, it’s moist, it’s pink, it’s stretchy.” (Mary Roach, 09:05)
  • This process is mostly used in gender-affirming surgery or in complex reconstructive cases.

The Penis Rebuild: Middle Finger Transplants

[Segment starts at 10:10]

• Roach tracks down an eyebrow-raising surgery, first heard about via a stem cell researcher: rebuilding a penis using a patient’s middle finger (with modifications).
  • “I… imagined the finger removed and installed pretty much as is, you know, with the nail.” (Mary Roach, 10:45)
  • Travels to Tbilisi, Georgia (the country!) to investigate.
  • Reality: The finger is wrapped in skin, not just transplanted as a finger.
  • Memorable Moment: Amusingly, the reconstructed organ could even support a ceramic water pitcher, as shown in an after-surgery photo.
    • “It looked quite normal, except that it does actually bend at the knuckle… There’s an image of the penis kind of bent upward partway along, and there’s a ceramic water pitcher being held by the penis.” (Mary Roach, 12:02)

The Future: Toward Cyborgs and Bioprinting

[Segment starts at 12:31]

• Roach tempers the excitement for immediate cyborg upgrades:
  • “Not yet, Gina, but it’ll happen. I mean, it’ll happen. All these things are on the way. Same with bioprinting.” (Mary Roach, 12:50)
• Bioprinting is still in its infancy.
  • “We’re kind of at the Wright brothers stage, if you want to compare it to aviation.” (Mary Roach, 13:20)
  • Emphasizes excitement—early-stage scientists achieved flight, but “a long way off from thousands of flights going back and forth every day.”

Notable Quotes & Memorable Moments

• On Artificial Body Parts:
  “Is there anything that we humans have built or designed or cooked up that is 100% perfect or pretty much just does what the original part does?... we can’t really even replace tears.” (Mary Roach, 00:53)

• On Being in an Iron Lung:
  “I will say your breathing feels the way your breathing does when you’re not in an iron lung, except that you have absolutely no control over when you’re going to inhale and when you’re going to exhale. The machine has taken over.” (Mary Roach, 05:28)

• On Human Ingenuity:
  “I can’t think of any other body part that would do double duty as a vagina… it’s tubular, it’s moist, it’s pink, it’s stretchy.” (Mary Roach, 09:05)

• On the Middle-Finger Penis Rebuild:
  “It looked quite normal, except that it does actually bend at the knuckle… there’s a ceramic water pitcher being held by the penis.” (Mary Roach, 12:02)

• On the State of Bioprinting Organs:
  “We’re kind of at the Wright brothers stage, if you want to compare it to aviation.” (Mary Roach, 13:20)

Segment Timestamps

• 00:24 — Regina’s childhood fantasies and the premise of Replaceable You
• 00:53 — Mary Roach on the limits of artificial body parts (tears)
• 01:56 — Burn treatments and skin culture advances
• 04:07 — The history and mechanics of the iron lung
• 05:28 — Personal experience: Trying the iron lung
• 07:11 — Iron lung vs. modern ventilators, pros and cons
• 08:35 — Surgical creation of vaginas using the colon
• 10:10 — Penis reconstruction using middle fingers and a funny aftermath
• 12:31 — The future: Cyborgs and organ bioprinting

Conclusion

This episode serves up a fast-paced, entertaining, and thought-provoking look at just how “replaceable” the human body is—with plenty of surprising historical context and eyebrow-raising medical facts. Roach’s humor and curiosity, paired with Barber’s insightful hosting, make for a compelling listen, whether you hope to be a future cyborg or just marvel at the creativity of medical science.

“Not yet, Gina, but it'll happen.” (Mary Roach, 12:50)