pipes, and at an emergency aid station, he nibbled a biscuit and vomited. He slept that night beneath an overturned boat on a beach. His left arm, fully exposed to the great white flash, had turned black.
All the while, beneath his incinerated skin, Yamaguchi’s DNA was nursing even graver injuries. The nuclear bomb at Hiroshima released (among other radioactivity) loads of supercharged x-rays called gamma rays. Like most radioactivity, these rays single out and selectively damage DNA, punching DNA and nearby water molecules and making electrons fly out like uppercut teeth. The sudden loss of electrons forms free radicals,highly reactive atoms that chew on chemical bonds. A chain reaction begins that cleaves DNA and sometimes snaps chromosomes into pieces.
By the mid-1940s, scientists were starting to grasp why the shattering or disruption of DNA could wreak such ruin inside cells. First, scientists based in New York produced strong evidence that genes were made of DNA. This upended the persistent belief in protein inheritance. But as a second study revealed, DNA and proteins still shared a special relationship: DNA
made
proteins, with each DNA gene storing the recipe for one protein. Making proteins, in other words, was what genes did—that’s how genes created traits in the body.
In conjunction, these two ideas explained the harm of radioactivity. Fracturing DNA disrupts genes; disrupting genes halts protein production; halting protein production kills cells. Scientists didn’t work this out instantly—the crucial “one gene/one protein” paper appeared just days before Hiroshima—but they knew enough to cringe at the thought of nuclear weapons. When Hermann Muller won his Nobel Prize in 1946, he prophesied to the
New York Times
that if atomic bomb survivors “could foresee the results 1,000 years from now… they might consider themselves more fortunate if the bomb had killed them.”
Despite Muller’s pessimism, Yamaguchi did want to survive, badly, for his family. He’d had complicated feelings about the war—opposing it at first, supporting it once under way, then shading back toward opposition when Japan began to stumble, because he feared the island being overrun by enemies who might harm his wife and son. (If so, he’d contemplated giving them an overdose of sleeping pills to spare them.) In the hours after Hiroshima, he yearned to get back to them, so when he heard rumors about trains leaving the city, he sucked up his strength and resolved to find one.
Hiroshima is a collection of islands, and Yamaguchi had tocross a river to reach the train station. All the bridges had collapsed or burned, so he steeled himself and began crossing an apocalyptic “bridge of corpses” clogging the river, crawling across melted legs and faces. But an uncrossable gap in the bridge forced him to turn back. Farther upstream, he found a railroad trestle with one steel beam intact, spanning fifty yards. He clambered up, crossed the iron tightrope, and descended. He pushed through the mob at the station and slumped into a train seat. Miraculously the train pulled out soon afterward—he was saved. The train would run all night, but he was finally headed home, to Nagasaki.
A physicist stationed in Hiroshima might have pointed out that the gamma rays finished working over Yamaguchi’s DNA in a millionth of a billionth of a second. To a chemist, the most interesting part—how the free radicals gnawed through DNA—would have ceased after a millisecond. A cell biologist would have needed to wait maybe a few hours to study how cells patch up torn DNA. A doctor could have diagnosed radiation sickness—headaches, vomiting, internal bleeding, peeling skin, anemic blood—within a week. Geneticists needed the most patience. The genetic damage to the survivors didn’t surface for years, even decades. And in an eerie coincidence, scientists began to piece together how exactly genes function, and fail, during those very
All the while, beneath his incinerated skin, Yamaguchi’s DNA was nursing even graver injuries. The nuclear bomb at Hiroshima released (among other radioactivity) loads of supercharged x-rays called gamma rays. Like most radioactivity, these rays single out and selectively damage DNA, punching DNA and nearby water molecules and making electrons fly out like uppercut teeth. The sudden loss of electrons forms free radicals,highly reactive atoms that chew on chemical bonds. A chain reaction begins that cleaves DNA and sometimes snaps chromosomes into pieces.
By the mid-1940s, scientists were starting to grasp why the shattering or disruption of DNA could wreak such ruin inside cells. First, scientists based in New York produced strong evidence that genes were made of DNA. This upended the persistent belief in protein inheritance. But as a second study revealed, DNA and proteins still shared a special relationship: DNA
made
proteins, with each DNA gene storing the recipe for one protein. Making proteins, in other words, was what genes did—that’s how genes created traits in the body.
In conjunction, these two ideas explained the harm of radioactivity. Fracturing DNA disrupts genes; disrupting genes halts protein production; halting protein production kills cells. Scientists didn’t work this out instantly—the crucial “one gene/one protein” paper appeared just days before Hiroshima—but they knew enough to cringe at the thought of nuclear weapons. When Hermann Muller won his Nobel Prize in 1946, he prophesied to the
New York Times
that if atomic bomb survivors “could foresee the results 1,000 years from now… they might consider themselves more fortunate if the bomb had killed them.”
Despite Muller’s pessimism, Yamaguchi did want to survive, badly, for his family. He’d had complicated feelings about the war—opposing it at first, supporting it once under way, then shading back toward opposition when Japan began to stumble, because he feared the island being overrun by enemies who might harm his wife and son. (If so, he’d contemplated giving them an overdose of sleeping pills to spare them.) In the hours after Hiroshima, he yearned to get back to them, so when he heard rumors about trains leaving the city, he sucked up his strength and resolved to find one.
Hiroshima is a collection of islands, and Yamaguchi had tocross a river to reach the train station. All the bridges had collapsed or burned, so he steeled himself and began crossing an apocalyptic “bridge of corpses” clogging the river, crawling across melted legs and faces. But an uncrossable gap in the bridge forced him to turn back. Farther upstream, he found a railroad trestle with one steel beam intact, spanning fifty yards. He clambered up, crossed the iron tightrope, and descended. He pushed through the mob at the station and slumped into a train seat. Miraculously the train pulled out soon afterward—he was saved. The train would run all night, but he was finally headed home, to Nagasaki.
A physicist stationed in Hiroshima might have pointed out that the gamma rays finished working over Yamaguchi’s DNA in a millionth of a billionth of a second. To a chemist, the most interesting part—how the free radicals gnawed through DNA—would have ceased after a millisecond. A cell biologist would have needed to wait maybe a few hours to study how cells patch up torn DNA. A doctor could have diagnosed radiation sickness—headaches, vomiting, internal bleeding, peeling skin, anemic blood—within a week. Geneticists needed the most patience. The genetic damage to the survivors didn’t surface for years, even decades. And in an eerie coincidence, scientists began to piece together how exactly genes function, and fail, during those very
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