Footage released by the animal-rights group Peta reveals, for the first time, filmed experiments at the University of Washington’s National Primate Research Center (WaNPRC), in which newborn monkeys were separated from their mothers and subjected to neurological tests after prenatal exposure to a neurotoxin.
Records show that the infant monkeys, some just two days old, were used in research on domoic acid, a toxin produced by marine algae that accumulates in shellfish and can cause illness in humans. The experiments were part of a project that ran for six years until 2020.
The footage shows monkeys with electrodes attached to their heads, undergoing tests to investigate whether exposure to domoic acid in the womb had damaged their brains. The baby monkeys appear distressed as they clutch blankets, suck their fingers, screech, and jerk as experimenters shave their heads and test their reflexes and memory.
The infant macaques were bred at the University of Washington’s Infant Primate Research Laboratory for the project researching the developmental neurotoxicity of domoic acid in nonhuman primates. Researchers administered doses of domoic acid daily to 32 pregnant macaques. After birth, 28 infants were removed from their mothers, bottle-fed and kept in incubators before being housed individually at three weeks old.
“These monkeys are so young they still have the distinctive black fur of newborn macaques, yet instead of clinging to their mothers, they grasp blankets on metal tables,” says Peta’s chief science adviser on primate issues, Dr Lisa Jones-Engel.
In the wild, macaques live in close social groups. Infants have long-term maternal care needs for their social and behavioral development, says Dr Malene Hansen, a long-tailed macaque expert, and cannot thrive without their mothers. “It is unethical to conduct research that separates infant macaques from their mothers. Period,” she says.
The WaNBRC told the Guardian: “We recognize that research involving infant animals raises important questions about their wellbeing. Maternal relationships and early social development are important considerations in nonhuman primate welfare. Our experienced veterinary and animal care personnel have specialized expertise in primate care, including nursery rearing.”
The project ran from 2014 to 2020 and received more than $4.2m in National Institutes of Health (NIH) funding. Some experiments lasted years. According to Peta, the monkeys were killed after the experiments were concluded.
The NIH says it takes the care and use of laboratory animals very seriously: “All animals used in NIH-supported research are protected by laws, regulations and policies designed to ensure the smallest possible number of animals are used and their welfare is prioritized.”
According to the WaNBRC, there are no current infant studies at its center; however, protocols for such studies are active.
Jones-Engel says: “There is no moral escape hatch. You can’t claim primates are used because they’re so like us, then take an infant away from its mother and experiment on it. You would never do that to a human primate. The cruelty also has biological consequences: maternal separation alters an infant’s physiology, immunity, behavior and development, distorting its response to the very substance or disease being studied.”
Jones-Engel worked as a primate scientist at the University of Washington for 17 years and has spent 35 years working as a primatologist. Her transition from animal researcher to campaigner is documented in a new film, Sentient.
Now one of the University of Washington’s most outspoken critics, Jones-Engel says the footage offers a rare glimpse into experiments involving monkeys: “For decades, the term ‘primate research’ has obscured the reality inside laboratories. These videos expose the suffering and raise a fundamental question: why are these facilities still operating at all?”
Peta is calling for the closure of all seven US National Primate Research Centers.
The footage relates to a research program that has operated at the University of Washington’s Infant Primate Research Laboratory since 1971 and emerges amid a long-running dispute between Peta and the university. In a 2020 lawsuit, Peta challenged the school’s handling of public-records requests. The court ruled that the university violated laws by failing to adequately search for records, in a case that revealed systematic destruction of photos and videos at the school.
The footage was released to Peta in September 2026 in response to a records request. The videos were filmed between 2017 and 2019.
The WaNPRC says the monkey studies have contributed to an understanding how prenatal domoic acid exposure may affect learning and memory: “These findings remain relevant to public health.”
However, there is no clear evidence that the experiments led to changes in public health recommendations.
Although the domoic acid research ended in 2020, records show that the WaNPRC continued to breed, purchase and use monkeys, including infants, to study viruses such as Epstein-Barr and HIV.
In a 2021 study, 25 infant rhesus macaques were infected with SIV, which is closely related to HIV. The study was looking at why some infants develop Aids more rapidly than others. The infected baby monkeys experienced significant distress, chronic diarrhea and body wasting, before they were killed for autopsy. In another study, 10 infant monkeys were separated from their mothers within two days of birth to test an experimental Epstein-Barr vaccine.
While supporters argue that biological similarities between humans and nonhuman primates make monkeys useful for studying human disease, decades of animal research has yet to produce an approved HIV vaccine.
Research scientist Dr Jarrod Bailey argues that biological differences mean monkey experiments often fail to deliver treatments for human diseases, including HIV/Aids, Alzheimer’s and Parkinson’s. “We pay the price in failed treatments; monkeys pay with their lives. A shift away from monkey experiments would benefit all primates – including humans.”
The University of Washington says it is committed to replacing, reducing and refining animal experiments through emerging technologies and improved animal care, but says that “animal studies remain necessary for some complex scientific questions”.
In the US, federal agencies are shifting towards reducing animal testing in favor of new approach methodologies, including organ-on-a-chip technology and computer modeling. The NIH is also investing in human-based alternatives. Yet primate research remains widespread: more than 106,000 monkeys were held in US facilities in 2025, up 1.5% from 2024, and more than 32,000 primates were imported from Asia and Africa for laboratory use from 2025 to 2026.