What happens when our thirst for knowledge drains some animal populations dry?
by Katie Law
The use of animals in scientific research has a long and checkered history. Animals have been invaluable in developing lifesaving cures such as penicillin (mice), in finding vaccines against diseases such as polio (monkeys), and in pioneering techniques such as organ donation (pigs). Dogs and frogs have been sent into space, sheep have been cloned and countless fruit flies, rats and mice have given their lives to scientific discovery. We just couldn’t have done it without them.
The vast majority of animals used in scientific research are specifically bred for their purpose, so the native population of Drosophila melanogaster is in no danger in the wild. But where captive breeding is too difficult or costly, the animals may be caught from the wild. Over enthusiasm for certain particularly useful species has in the past been seriously problematic, and some animals have been hunted to dangerous levels in the name of science.
Take for example the medicinal leech, Hirudo medicinalis. Thanks to their popularity in nineteenth century Europe as the cure du jour for a wide range of ailments, demand outstripped supply and the leech was hunted to near extinction. Any enterprising individual with a low squeamishness threshold could obtain a valuable stash of leeches merely by wading through a nearby marsh with no trousers on. They fell out of favor when it became clear that leeched patients didn’t necessarily fare better than non-leeched patients. Today, the medicinal leech sits on the IUCN Red List, bearing the warning flag of “near threatened.” Pretty impressive for a species that few would want to touch with a ten-foot pole.
These days leeches are experiencing a return to favor in medicine. They can reduce swelling and promote circulation by draining areas of excess blood, thanks to their anticoagulant saliva and thirst for the red stuff. So useful are they that they have just been given Food and Drug Administration approval as an official medicinal device. Luckily, it’s relatively easy to farm leeches for medical purposes, so they’re less at risk from extinction this time around. You can still find them in mulchy bogs in Kent and Scotland (among other places), should you feel the need to visit them in their natural habitat.
But leeches are the lucky ones. The humble leopard frog and bullfrog – whose dissections are staple of the U.S. biology curriculum – are still collected from the wild, often along the border between the U.S. and Mexico. The Humane Society of the U.S. estimates that about 3 million frogs are dissected in classrooms each year. A 1971 study estimated that 9 million frogs were collected from wild U.S. populations and used in dissection and medical research.
Not surprisingly, numbers of leopard and bullfrogs are decreasing. While harvesting of frogs is just one among their many ecological problems, which include disease, climate change and habitat loss, collections certainly don’t help. The IUCN does not consider bullfrogs endangered – they carry the IUCN label of least concern – but mainly because they are tolerant to a range of habitats. Northern leopard frogs are considered of special concern or endangered in some Canadian provinces. Seven leopard frog species in the U.S. are protected or endangered under local classifications.
In the case of rhesus macaques, it was actually the ease with which researchers could house the animals in captivity that led to their demise in the wild. Macaques are often used in biomedical and behavioral research because they resemble humans reasonably closely in terms of anatomy and physiology, cognition and behavior. Throughout the early twentieth century, these wee little primates were available by the bagful from their native northern India for cheap, cheap, cheap. But by the time export of these animals from India came under scrutiny in the late 1970s, it is estimated that some easily accessible populations had been reduced by up to 90%. At the moment, these animals are on the IUCN Red List, but have the same relatively low conservation status as leeches (low risk, near threatened). Captive breeding institutions struggle to keep up with demands.
In our modern, ecologically minded world, these are mistakes that should not be repeated. Above all, the scientists should know better. But they don’t. Even now Japanese researchers are fighting to be able to conduct studies on Japanese macaques (yes, those ones who like to hot tub in geothermal pools). When macaques were listed as endangered in 1996 by the IUCN, the Japanese medical research community protested, saying that access to crops had allowed macaque populations to boom and become pests. The Japanese environmental agency said that allowing wild macaques to be captured for lab tests fueled illegal and overzealous harvesting. Today Japanese macaques are listed as DD – data deficient. If there is one thing that a scientist perpetually is, it’s data deficient. Looks like we’ll never learn.
This article reprinetd under special arrangement with Inkling Magazine
