UC Davis veterinary records cited by the Physicians Committee—which WIRED also obtained through a subsequent California public records request—chronicle a battery of complications that developed following procedures involving electrodes being surgically implanted into monkeys’ brains. The complications include bloody diarrhea, partial paralysis, and cerebral edema, a conditional colloquially known as “brain swelling.”
For example, in an experimental surgery that took place in December 2019, performed to determine the “survivability” of receiving an implant, an internal part of the device “broke off” while being implanted. Overnight, researchers observed the monkey, identified only as “Animal 20” by UC Davis, scratching at the surgical site, which emitted a bloody discharge, and yanking on a connector that eventually dislodged part of the device. A surgery to repair the issue was carried out the following day, yet fungal and bacterial infections took root. Vet records note that neither infection was likely to be cleared, in part because the implant was covering the infected area. The monkey was euthanized on January 6, 2020.
Additional veterinary reports show the condition of a female monkey called “Animal 15” during the months leading up to her death in March 2019. Days after her implant surgery, she began to press her head against the floor for no apparent reason; a symptom of pain or infection, the records say. Staff observed that though she was uncomfortable, picking and pulling at her implant until it bled, she would often lay at the foot of her cage and spend time holding hands with her roommate.
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.”
Yet another monkey, Animal 22, was euthanized in March 2020 after his cranial implant became loose. A necropsy report revealed that two of the screws securing the implant to the skull loosened to the extent they “could easily be lifted out.” The necropsy for Animal 22 clearly states that “the failure of this implant can be considered purely mechanical and not exacerbated by infection.” If true, this would appear to directly contradict Musk’s statement that no monkeys died as a result of Neuralink’s chips.
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.
A doctoral candidate currently conducting research at the CNPRC, granted anonymity due to a fear of professional retaliation, likewise questions Musk’s claim regarding the baseline health of Neutralink’s monkeys. “These are pretty young monkeys,” they tell WIRED. “It’s hard to imagine these monkeys, who were not adults, were terminal for some reason.”
“We have no comment to make regarding Elon Musk’s statements,” Andy Fell, a spokesperson for the Davis campus, tells WIRED.
If the SEC does investigate Musk’s comments, it would mark at least the third federal probe linked to Neuralink’s animal testing. In December 2022, Reuters reported that the US Department of Agriculture’s Office of Inspector General had launched a probe into Neuralink’s treatment of some animal test subjects. In February 2023, the US Department of Transportation opened an investigation into Neuralink over allegations of unsafe transport of antibiotic-resistant pathogens.
These investigations followed the US Food and Drug Administration (FDA) initially rejecting Neuralink’s application, in early 2022, for approval to conduct in-human clinical trials. According to Reuters, the agency’s major concerns involved the device’s lithium battery as well the possibility that the implant’s wires might migrate to other parts of the brain. This May, the FDA gave the company approval for human trials.
Those human trials could soon begin. Yesterday, Neuralink announced it had received approval from an independent review board to begin a study aiming to enable people with paralysis to control a computer keyboard or cursor with their thoughts.