Can you transplant a head to another body? - Max G. Levy

513,881 views ・ 2024-06-04

TED-Ed


Please double-click on the English subtitles below to play the video.

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On March 14th, 1970, Robert White and his team carted two small monkeys
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into an operating room.
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The neurosurgeon lay on the verge of an ambitious experiment,
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decades in the making, which was bizarre,
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if not pulled straight from his own fever dream.
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White’s objective?
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Connect the head of Monkey A to the body of Monkey B,
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in what he considered a whole-body transplant.
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White’s ultimate goal was to one day perform this surgery on humans.
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While disturbing, the idea of a body transplant
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raises ethical, biological, and philosophical questions—
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on the nature of life and the limits of science—
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that are still discussed today.
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But first, is it even medically possible?
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White's surgery faced several technical hurdles.
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For one thing, it guaranteed paralysis
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as no doctor then— or now— could reconnect a severed spinal cord.
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But White, a practicing neurosurgeon,
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thought the surgery could be life-saving
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for his patients with spinal cord injuries or progressive mobility diseases like ALS.
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These patients often face multi-organ failures and paralysis,
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so with a body transplant,
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he hoped to save their lives by replacing all of their organs at once.
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But paralysis wasn't the only challenge.
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Due to their high energy demands,
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brain cells require a constant supply of oxygenated blood to survive.
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Yet the transplant surgery would likely interrupt the brain’s oxygen flow
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for hours.
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But White had an idea.
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When the brain is cold,
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its metabolism slows down and it relies less on oxygen.
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Experimenting on dogs and monkeys,
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White optimized a brain-cooling technique
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where the brain’s blood flow was selectively chilled and halted,
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while the rest of the body’s blood remained warm and circulated.
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Then, in 1964, White successfully cooled the brain of a human patient
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with a life-threatening brain tumor into “suspended animation” at 11°C.
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Whereas normally the surgical team would have just 3 to 5 minutes
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to remove the tumor,
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with this new technique,
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they operated for over an hour without causing damage.
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Brain cooling revolutionized the field of neurosurgery
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and put White one step closer to his body transplant goal.
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But this vision was fraught with serious ethical concerns.
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What conditions would justify such an experimental surgery,
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that could result in debilitating pain and neurological damage?
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And how many animals would have to die to prove it was possible?
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At the time, bioethics was still an emerging field.
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Nevertheless, numerous critics, including many in the scientific community,
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recognized the cruelty of White's research and strongly opposed it.
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Yet White continued to gain approval from agencies like the NIH.
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And by 1970, he was ready to attempt a monkey body transplant.
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First Monkey A was installed with temporary blood vessels—
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coils of plastic tubes that tethered the head to the body.
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Plastic tube by plastic tube, the team connected Body B to Head A,
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and then waited for the subject to awake from anesthesia.
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The monkey did— alive, paralyzed, and extremely distressed.
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According to the team, the monkey could see, smell, hear,
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and even tried to bite off one of the doctors’ fingers.
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White felt this proved that the operation could work.
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The brain appeared to survive a head transplant
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and, with high doses of drugs, could live without immune rejection.
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But had White performed a body transplant on Monkey A?
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Or was it a head transplant on Monkey B?
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The surgery raises questions about the mind-body divide
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that have been debated for millennia.
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While modern neuroscience supports the central role of the brain
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in building out our consciousness,
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discoveries about gut neurons and the microbiome
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suggest that the answer may be more complicated.
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Does part of the “self” reside outside of the mind?
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The body and brain are interconnected by circuits and signaling systems;
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so, what is lost by separating the two?
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As a neurosurgeon, White performed more than 10,000 brain operations
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before retiring in 1998—
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but never the human head transplant he dreamed of.
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Since then, several scientists have expressed interest in picking up
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where White left off, reviving unfinished debates.
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Even if a doctor could successfully connect a patient’s head
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to a donor’s body,
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who of the two would emerge?
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And is extending a life always worth the cost?
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