A "maverick surgeon" claims to have successfully put one monkey's head on another monkey's body, bringing the doctor one step closer to the first human head transplant, New Scientist reports.

Sergio Canavero announced his plans for a human head transplant as a treatment for paralysis last year. Since then, he's been working with scientists in China and South Korea on mice, monkeys, and human cadavers.

"It’s important that people stop thinking this is impossible," he says. According to Discovery, the head transplant surgery involves cooling both bodies to "a very low temperature" and cutting the neck and spinal cord with an "exceptionally sharp knife" before attaching the patient's head to the donor body.

The patient would recover during a four-month drug-induced coma. As for the supposedly successful monkey head transplant, New Scientist reports details are few. Canavero provided a photo of the monkey post-surgery and claims it "fully survived the procedure without any neurological injury." But his team says it only reattached the blood supply to the head—not the spinal cord—and euthanized the monkey after 20 hours for ethical reasons.

Fellow scientists are skeptical because Canavero has yet to publish any of his results. “When it gets published in a peer-reviewed journal I’ll be interested," one bioethicist says. "I think the rest of it is BS.” Another scientist says Canavero is seeking "publicity" at the expense of "good science." Canavero already has his first human head transplant patient lined up and plans to perform the operation in December 2017.

This article originally appeared on Newser: Surgeon Says Monkey Head Transplant Was Success

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