The human brain is an amazing piece of biological machinery responsible for everything from dreaming up Shakespeare’s sonnets to the muscle coordination of scoring a World Cup-winning goal. Yet, even if our brains remain spry into our old age, our bodies often don’t. What if we replaced them? 

That’s the idea of controversial neurosurgeon Sergio Canavero, who claims in a recent article that it could be “technically feasible” to stave off aging by simply scooping out a person’s brain and plopping it into a younger, more agile body. The article, called “Whole brain transplantation in man: Technically feasible” was published in Surgical Neurology International (SNI), a peer-reviewed journal where Canavero serves as an editor. 

If this procedure is ringing any bells, it may be because Canavero put forward a similar idea in 2015 that proposed a full head transplant. The claim was bombastic, highly controversial, and, when he later said he had found a volunteer to undergo the procedure, became international news. It became such a sensation that it was  part of a Metal Gear Solid–related conspiracy theory. Many doctors disregarded the procedure as not based in current science, and it has not been completed in a live human subject to date. 

Canavero told Motherboard in an email that head transplants “work,” and that his previous work was just a stepping stone to a brain transplant.

“A human head transplant was the intermediate step towards a brain transplant. Since the latter is considered impossible, I decided to focus on HT [head transplant], which is far simpler,” Canavero said. “However, although I can tell you HT works, unfortunately it does not rejuvenate aged head tissues, including the eyes. BT [Brain transplant] is the only option.”

Canavero’s claims regarding head transplants have been difficult to verify. In 2017, SNI published work by Canavero and Chinese colleague Xiaoping Ren—who is also on SNI’s editorial board—reporting a head transplant rehearsal with human cadavers. A live volunteer subject, a Russian man with a genetic degenerative muscle atrophying disease, pulled out of the planned procedure in 2019. Also in that year, SNI published work by Canavero and Ren claiming to report successful spinal cord repair in animals. 

Canavero told Motherboard he’s not free “to talk about the HT project that unfolded in China, other than saying it works.”

In his latest paper—which is co-edited by himself and Ren—Canavero describes how to theoretically remove one person’s brain to place it into the skull of either a clone or a donated and brain-dead “immunoconditioned” body. In addition to describing a “robotic scoop with retractable tines” that would pluck the brains from their skulls, Canavero also provides possible solutions to several outstanding questions surrounding brain transplants, including nerve and vascular reconnection methods.

“The unavailability of technologies that can successfully rejuvenate an aged body suggests that it is time to explore other options,” the paper notes. “Contrary to common lore, a full BT is achievable, at least theoretically. Of course, further extensive cadaveric rehearsals will be necessary, followed by tests in brain-dead organ donors (as e.g., done recently in kidney xenotransplants). New surgical tools will have to be developed. With appropriate funding, a long-held dream may finally come true.”

The ultimate goal of such a procedure would be to extend the number of years a person could enjoy living in a “pristine body,” Canavero writes in his paper. This reasoning is not dissimilar to that used by CRISPR advocates who propose using the technology on embryos to snip out unwanted genetics that may lead to physical or mental disabilities—a goal which some experts have flagged as being a revival of eugenics.

Problematic or not, there is big interest in extending human life, and an entire branch of science and pseudoscience dedicated to “transhumanism” and life extension, including among Silicon Valley elite. These methods include everything from taking specific substances to “young blood” transfusions, cryogenics, and attempts to recreate humans as immortal AI. Thus far, these attempts have not included having one’s brain transplanted into a clone of themselves. 

There are still major questions about whether or not what Canavero proposes would ever actually work in a living human being (especially since part of the solution hinges on developing human clones), but his claims will surely continue to capture the interest—and horror—of the public.