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The Not-So-Mad Science of Head Transplants

by Mark Hay

October 31, 2014
Illustration by Tyler Hoehne and Addision Eaton

Last year, when Sergio Canavero of Italy’s Turin Advanced Neuromodulation Group announced that in the near future he’d be able to transplant a human head onto another body, people didn’t call him mad (MAD!) at the universities. And instead of setting upon Canavero with pitchforks and torches, the medical establishment seemed content to just write him off as idealistic and impractical.

But as radical as splicing heads sounds, we’ve known for decades how to keep a head and brain alive and functional long enough to graft it onto another body. We’ve just never been very good at fusing the spine back together, which would allow the newly transplanted head to communicate with the host body. Last year, scientists demonstrated that substances called fusogens could partially repair severed spines in rats, and Canavero claims his Head Anastomosis Venture with Cord Fusion surgery can use these proteins to solve the spinal problem in humans. But critics point out that the operation would most likely only be effective at repairing clean, surgical cuts to the spinal cord (if that) rather than reliably fixing real-world injuries. And with each surgery requiring 100 surgeons for 36 hours at a potential cost of $12.8 million, even the most optimistic were forced to dismiss Canavero’s vision as a pipe dream. Yet what seemed like a pipe dream just last year seems less mad every day as new discoveries push this kind of surgery from the realm of impossibility to mere ethical quandary.

The modern head transplant dates back to 1970, when an American Dr. Robert J. White grafted a monkey’s head onto another body. By moving swiftly, cauterizing arteries as they were severed to prevent blood loss, putting the donor body into cardiac arrest, and using fast artery-stitching technology, he was able to revive a head that could taste, smell, hear, and see. But the monkey, say those who were present (like Dr. Jerry Silver, whose research to his chagrin has inspired Canavero), had a look of pain, confusion, and anxiety for the short and miserable time it was alive on the paralyzed host body. To many, the surgery seemed like a reckless, horrifying, and inhumane Frankensteinian folly that ought never to be repeated.

Photo by Weiß, Günter/Wikimedia Commons

But even back in 1970, the monkey transplant experiment wasn’t completely novel. We’ve been working on head graft technology since at least 1908, when American Dr. Charles Guthrie managed to attach a dog’s head (after 20 minutes of death) onto the body of another living dog, creating a two-headed beast whose transplanted head could still focus its pupils and twitch its tongue before death. In the 1950s, Soviet Dr. Vladimir Demikhov improved the process, making at least 20 two-headed dogs. The second heads actually functioned normally, staying alive for about a week before the host immune systems rejected them. The experiment was repeated on monkeys in 2001 and rats in 2002.

Since last year, there have been a few optimistic developments for head transfers. Recent work in the United States and Germany has advanced our knowledge on how to fuse and more fully restore function in the spine, meaning those who scoffed at Canavero and his fusogens might have less of a critical leg to stand on. Spine repair is still in its infancy, and there’s still work to be done to make sure a host body doesn’t reject the head transplant. But even without a fully functional spine, the surgery may still have practical uses right now (if we can get the costs down) for quadriplegics suffering organ failure and others who’d rather live with impairment than die.

With many disabled patients who might be willing to take the risk, the hurdle stopping us from seeing human head transplants may be more about ethics than ability. How does one reconcile, for instance, using a whole body whose organs could save many individuals to only save one person? A possible solution could come from a series of mid-1990s experiments in the United States and England, which developed headless mice and frog bodies by manipulating the genes in eggs, potentially creating uncomplicated donor bodies. But creating headless human bodies for transplant is far off in the sci-fi future and certainly carries its own ethical morass. So while for now we’re stuck with the impractical dreams of Dr. Canavero, it would be foolish to write off the possibility that transferring a head may one day be as feasible as transplanting hearts, lungs, or kidneys—all once medical pipe dreams or futuristic fantasies. With each tweak and successful repetition, hopes grow that the procedure could become a common clinical reality within the century.

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The Not-So-Mad Science of Head Transplants