Here are the details on the grisly deaths of Elon Musk’s Neuralink monkeys

Illustration by Lille Allen / The Verge

Elon Musk said earlier this month that “no monkey has died as a result of a Neuralink implant,” but an alarming new report from Wired seems to contradict Musk’s statement. Public documents obtained by the Physicians Committee for Responsible Medicine (PCRM) and seen by Wired indicate that Neuralink’s macaque subjects were euthanized after suffering various complications, including “bloody diarrhea, partial paralysis, and cerebral edema.”

Wired writes that the documents show a male monkey was euthanized in March 2020 “after his cranial implant became loose,” with the necropsy revealing “the failure of this implant can be considered purely mechanical and not exacerbated by infection.”

On Tuesday, Neuralink announced it’s starting in-human trials for people with quadriplegia.

The PCRM is a nonprofit that advocates against using live animals in testing that sued UC Davis to get the documents from the California National Primate Research Center (CNPRC), a bioresearch facility at the school where testing took place. Those are now posted on its website and cited in the letters it sent to the Securities and Exchange Commission on Wednesday accusing Musk of securities fraud, referencing the reported $280 million Neuralink has raised from investors to create a brain computer interface. A spokesperson for UC Davis declined to comment to Wired.

Wired notes a December 2019 experiment outlined in one of the documents saying one monkey had to be euthanized after a piece of Neuralink’s brain implant broke off during the surgical process, leading to infection. Another macaque mentioned — known as Animal 15 — “began to press her head against the floor for no apparent reason” days after receiving the implant, and her condition only went downhill from there:

Animal 15 began to lose coordination and staff observed that she would shake uncontrollably when she saw lab workers. Her condition deteriorated for months until the staff finally euthanized her. A necropsy report indicates that she had bleeding in her brain and that the Neuralink implants left parts of her cerebral cortex “focally tattered.”

Along with claiming that no monkeys have died because of a Neuralink implant, Musk has said the startup “chose terminal mon[k]eys (close to death already)” as test subjects to “minimize risk to healthy monkeys.” However, Wired cites an anonymous former employee saying that is not true:

Shown a copy of Musk’s remarks on X about Neuralink’s animal subjects being “close to death already,” a former Neuralink employee alleges to WIRED the claim is “ridiculous” if not a “straight fabrication.” “We had these monkeys for a year or so before any surgery was performed,” they say. The ex-employee, who requested anonymity for fear of retaliation, says up to a year’s worth of behavioral training was necessary for the program, a time frame that would exempt subjects already close to death’s door.

Last year, the PCRM filed a complaint with the US Department of Agriculture (USDA) alleging that Neuralink’s practices violate the Animal Welfare Act. Neuralink also faces an investigation from the US Department of Transportation over allegations it illegally transported contaminated devices that were removed from monkeys’ brains.

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