Radiolab: "Double Blasted" (July 16, 2012)

Podcast: Radiolab
Host(s): Jad Abumrad, Robert Krulwich
Guest: Sam Kean (author, "The Violinist's Thumb")
Theme: Exploration of survival, genetic inheritance, and the resilience of DNA through the extraordinary true story of Tsutomu Yamaguchi, the man who survived both atomic bombings in Japan in 1945.

Episode Overview

This episode tells the incredible story of Tsutomu Yamaguchi, a Japanese ship engineer who survived both the Hiroshima and Nagasaki atomic bombings. The conversation dives into the immediate and long-term effects of radiation on the human body, especially DNA. The discussion is richly scientific, yet deeply human, exploring whether radiation-induced genetic damage truly persists across generations—a question loaded with fear, myth, and scientific insight.

Key Discussion Points & Insights

1. The Story of Tsutomu Yamaguchi

• Yamaguchi's Background (00:53)
  • Japanese ship engineer working for Mitsubishi.
• First Bombing: Hiroshima (01:02 – 05:48)
  • On August 6, 1945, while commuting to work, remembers forgetting his "incon" (official seal), returns to fetch it, delays his walk.
    • “He sits down for tea for a while with them. Then finally they let him go. He grabs his ink on, hops back on the bus...” (01:40)
  • At 8:15 AM, bomb detonates about a mile away; he sees a flash, hears a roar, is blasted unconscious.
    • “He drops to the ground, covers his head, and he plugs his thumbs into his ears and he waits for the big bang to go off.” (02:32)
    • “There was a very hot flash of very bright white light that sort of bathed over him. Then after that came the roar.” (02:46)
  • He regains consciousness, sees devastation and burning injuries on himself and others.
    • “It looked like he had this horrendous sunburn on both of his forearms, especially his left forearm, which was closer to the bomb.” (05:25)
• Desperate Journey Home (06:12 – 07:30)
  • Faced with destroyed infrastructure, crosses rivers filled with bodies, barely manages to catch a southbound train to his hometown, Nagasaki.
    • “He actually starts crawling over this bridge of bodies in the river because he had no other way of getting across.” (06:40)
• Second Bombing: Nagasaki (07:35 – 09:02)
  • Arrives in Nagasaki, reunites with family, is at Mitsubishi headquarters describing Hiroshima just as the second bomb detonates on August 9, 1945.
    • “His boss cuts him off and he says that this is complete baloney...as soon as he finished saying that, Yamaguchi felt the same flash that he'd felt in Hiroshima..." (08:19)
  • Survives the second blast, finds his family in an air raid shelter, but his health soon deteriorates.
    • “His hair fell out. He had boils erupting on his body. He kept throwing up. His face swelled. He lost hearing in one ear. His arm, he reported, looked like whale meat.” (09:27)

2. The DNA Damage and the Fears of a “Thousand Year Curse”

• Gamma Ray Impact (03:20 – 04:32)
  • Gamma rays from the bomb produce “free radicals” that rip apart DNA.
    • “DNA is a very thirsty molecule...gamma rays...form these very reactive molecules called free radicals...and they start to go after DNA.” (03:52)
• Extending Fear to Future Generations (09:52 – 11:10)
  • Scientists feared the radiation would cause heritable genetic mutations—a “biblical curse.”
    • “If the bomb survivors could foresee the results a thousand years from now, they might consider themselves more fortunate if the bomb had killed them.” - Herman Muller quote (10:20)
    • Damage to DNA occurs “in a millionth of a billionth of a second” but was imagined to have lasting effects. (10:54)

3. The Genetic Reality: What Actually Happened?

• Yamaguchi’s Family After the Bombings (12:05 – 13:39)
  • Despite fears, he and his wife decided to have more children. Daughters suffered some health issues but showed no severe birth defects or cancer.
    • “They had two daughters...the two daughters initially are fine...in their teenage years and especially as adults, having a lot of health problems...but still no cancer, no birth defects.” (13:11 – 13:39)
• Population Studies on Survivors’ Children (13:51 – 14:09)
  • No significant increase in birth defects or cancer among children of bomb survivors in Japan.
    • “The children of atomic bomb survivors in Japan...really didn't have a higher incidence of birth defects or cancer or anything like that.” (13:51)
• Why Didn’t the Genes “Stay Broken”? (14:45 – 16:24)
  • DNA in sex cells possibly more resilient; p53 “guardian of the genome” gene repairs DNA damage effectively.
    • “After 4 billion years, DNA can do a pretty good job of repairing itself...the p53 gene, that's sometimes called the guardian of the genome." (15:09)
    • Explanation of DNA’s double-strand structure and repair process.
• Cautions & Contrasts with Other Radioactive Events (16:41 – 17:09)
  • Not all radiation is equal—Chernobyl saw different, more deleterious hereditary effects; food-borne contamination more dangerous.

4. The Resilience of Life and DNA

• “Something that seems so unbelievably intricate and fragile, like a strand of DNA...can be so surprisingly resilient, that we can be so resilient.” (17:24)

5. Yamaguchi’s Life Story and Legacy

• Extraordinary Longevity (17:38 – 17:58)
  • Survived both bombs, lived until 2010 (age 93), 65 years after the events.
    • “He lived 65 years after [the bombings]... He was 93 years old when he finally died.” (17:49)

Notable Quotes & Memorable Moments

• On Yamaguchi watching the bomb drop:
  • “He looks up in the sky and...sees a plane way, way up above him…just see a very tiny speck descending from the belly of the plane...drops to the ground, covers his head...” (02:16–02:34)
• On instant DNA damage:
  • “The moment the light hit him, Tsutomu Yamaguchi's DNA got shredded.” (04:32)
• On the myth of the ‘Thousand Year Curse’:
  • “If the bomb survivors could foresee the results a thousand years from now, they might consider themselves more fortunate if the bomb had killed them.” – Herman Muller, quoted by Sam Kean (10:20)
• On the resilience of DNA:
  • “Turns out, after 4 billion years, DNA can do a pretty good job of repairing itself.” (15:09)
• On the broader meaning:
  • “That little tiny flame that we pass into the future...can be so surprisingly resilient, that we can be so resilient.” (17:24)
• On the man at the center of it all:
  • “He was 93 years old when he finally died.” (17:49)
  • “Oh, my God.” (17:58)

Key Timestamps

• 00:53 – 09:02: Tsutomu Yamaguchi's story of survival, including details of both bombings
• 09:52 – 11:10: Fear of heritable radiation damage ("Thousand Year Curse")
• 12:05 – 14:09: Outcomes for survivors’ children and observations from genetic studies
• 14:45 – 16:24: Explanation of DNA repair mechanisms, p53 gene, and why the apocalypse never came true
• 17:38 – 17:58: Yamaguchi’s ultimate legacy—he lived to 93

Tone

The episode weaves scientific explanation with emotional storytelling, maintaining Radiolab’s signature curiosity and mix of awe, humility, and hope. The scientists’ explanations are technical but always brought back to the human level, especially through Sam Kean’s gentle, narrative delivery.

Conclusion

Radiolab’s “Double Blasted” offers a gripping narrative blending history, human resilience, and modern genetics. Through Tsutomu Yamaguchi’s harrowing yet inspiring story, the episode challenges assumptions about radiation’s generational impact and celebrates the hidden strength and reparative power of DNA. As Sam Kean notes, life—and the genetic code that underlies it—is tougher and more adaptable than we may fear, providing a rare story of hope rooted in science and human endurance.