But more recently, they’ve also come to be seen in another light: as increasingly valuable test subjects for biomedical experiments, including for COVID-19 vaccines.
Until recently, the so-called “ common monkey of Southeast Asia ” proliferated farther and wider than almost any other nonhuman primate, evolving from what was once considered a sacred animal to a pest in the eyes of many.
“The population size is reducing at an alarming rate,” Malene Friis Hansen told VICE World News. She is a co-author of the IUCN report and a member of the organisation’s Primate Specialist Group, as well as a co-founder of the Long-Tailed Macaque Project. “In several populations over the past 10 years we've seen a reduction from a couple of thousand to a couple of hundred. That's the intensity right now: a tenfold reduction over only 10 years.”
Deforestation, human consumption, and culling have all contributed to the slide. But in the latest assessment, researchers cited the monkeys’ ongoing use as a “biological resource”—that is, the international and domestic trade of specimens for lab experiments, toxicity testing, and medical research—as the main factor behind the diminishment of the species.
Now Asia’s common monkey is in dire straits. On Thursday, the International Union for Conservation of Nature (IUCN)’s Red List of threatened species listed the long-tailed macaque as “ endangered ” for the first time. This marked the continuation of a worrisome trend: in 2020, the long-tailed macaque’s conservation status was escalated from “least concern” to “vulnerable,” skipping the intermediate rank of “near threatened” altogether.
What makes these primates particularly valuable to researchers is their genetic proximity to humans, which makes them ideal stand-ins for trialling potentially dangerous drugs and medicines.
“Demand is very, very high,” Hansen confirmed. “We even as conservationists get contacted by laboratories asking us if we can get some. It's quite intense. People are kind of battling each other to get to the monkeys and to have these monkeys for research.”
Every COVID-19 vaccine has involved preclinical testing on nonhuman primates, adding to existing research on a raft of diseases like HIV, multiple sclerosis, and Parkinson’s. And there is no nonhuman primate as widely used in research as the long-tailed macaque.
Yet not only are such threats and pressures ongoing, they’re increasing. The global demand for live research monkeys is booming, due in no small part to the global pandemic, as worldwide urgency for vaccine development meant the market for test subjects that closely resembled humans—like macaques—went through the roof.
If current trends continue, it’s thought that the global population of the long-tailed macaque could be on track to halve within the next 40 years. “If we don't start acting and start mitigating some of these threats and some of the pressure on the species,” said Hansen, “then it will go extinct.”
On June 30, Air France—one of the few remaining airlines that still ships live primates to research labs around the world—announced that it would stop transporting monkeys, amid mounting pressure from animal rights groups like PETA who have been calling on the carrier to “get out of bed with the animal experimentation industry.”
And supply, it seems, is about to be disrupted even further.
Leech further pointed out that there is currently an “absolute global shortage” of primates in the sector, making it difficult for scientists to pursue the “life-saving research” that depends upon them and necessitating “the increasing reuse of animals.”
“Scientists would probably rather use mice or zebrafish—they're cheaper, for example—but they're not appropriate,” Leech said. “[Primates] are the best available model for science.”
Any new drug must be tested on two animal species before gaining approval for human trials, he explained, and the main criteria for selecting test species is whichever has the best predictive potential for humans.
Kirk Leech, executive director for the European Animal Research Association (EARA), told VICE World News that while primates represent less than 1 percent of all animals used in biomedical research, they’re most commonly studied for drug development, vaccines, and therapeutics.
“In ten years' time, I'd be dismayed at what impact this will have on research,” he said.
Leech is concerned that if the few remaining airlines still transporting live primates follow suit then biomedical research, particularly in the West, could be significantly impeded by the lack of available test subjects. The solution would be for countries to establish their own breeding facilities and stock of research primates. But this would take years, Leech said. In the meantime, he added, the “clock [will] have stopped.”
“The loss of [supply through] Air France is a significant blow—no way of getting around the matter—because you did have an airline which for particular reasons stood out against activists and was prepared to transport [monkeys] to Europe and into the U.S.,” said Leech. “The Air France situation adds to the existential crisis surrounding the use of nonhuman primates.”
Not only did Leech dispute these allegations, defending the high ethical standards of the European research sector, he also raised serious concerns about that sector’s own existential crisis.
PETA celebrated the announcement as a “ massive victory for monkeys ,” claiming that more primates would now “remain in nature with their families instead of being trapped and imprisoned on decrepit breeding farms and inside terrifying laboratories.”
Such unprecedented demand has turned the global monkey trade into a seller’s market, with the going price for a live long-tailed macaque soaring from several thousand dollars a few years ago to upwards of $10,000 today. Leech told VICE World News he’d heard of a U.S. company paying as much as $50,000 for a single breeding primate.
For Leech, this is a worrying outcome. He explains that while groups like PETA might think it’s unethical to use nonhuman primates in biomedical research, he views the situation through a cost-benefit lens, claiming it would be “more cruel and more immoral not to use the best available science” to research “terrible, debilitating diseases.” If the supply of nonhuman primates suddenly dries up, though, scientists won’t have the choice.
“This will take time,” Behie said. “Any reduction in animal availability could slow the development of medical treatments.”
Alison Behie, a primate conservation researcher at the Australian National University, echoed Leech’s prediction, telling VICE World News that if the remaining airlines follow Air France’s lead, then countries like the U.S. will be left with no choice but to increase the number of breeding primates in country.
“Because of a shortage,” he said, “there's been a complete grab for primates anywhere.”
“The most brutal incident involved the killing of one captured male. Beaten down with a pole, the dazed and injured animal was dragged by his tail.”
China, previously the world’s biggest exporter of live primates, stopped trading wildlife internationally in the wake of the COVID-19 outbreak in a bid to prevent the spillover of zoonotic diseases. Cambodia stepped in to feed that demand, dominating the global monkey trade and swiftly overtaking China as the world’s biggest supplier.
While in 2019 the country exported 13,922 live monkeys, that number spiked to nearly 29,500 in 2020. More than two thirds of these were sent to the U.S., hundreds of which were wild-caught, according to data from the Convention on International Trade in Endangered Species, supplied by Sarah Kite, co-founder of advocacy group Action for Primates. Data for 2021 is expected to be released in November of this year.
The problem, according to Hansen, is that Cambodia doesn’t have nearly the same number of captive-bred specimens as China—meaning the Southeast Asian nation, which is a habitat country for the long-tailed macaque, is far more likely to be relying on wild-caught animals to supplement its exports.