by Hal Herzog
In the 1870s, the war on animal research heated up in England, and advocates on both sides of the issue sought the support of their country’s most renowned scientist. Darwin, however, gave mixed messages. He once referred to physiology as “one of the greatest of sciences.” Yet Darwin complained to a friend that surgery on animals should never be performed “for mere damnable and detestable curiosity.”
Ultimately, however, Darwin sided with his fellow biologists. His views on the value of animal research are reflected by a subtle change he made in the second edition of The Descent of Man. In the first edition, he wrote, “Everyone has heard of the dog suffering under vivisection, who licked the hand of the operator; this man, unless he had a heart of stone, must have felt remorse to the last hour of his life.” Three years later, however, he amended the sentence, adding: “unless the operation was fully justified by the increase in our knowledge.” In 1881, he laid his cards on the table, writing in a letter to the London Times, “I feel the deepest conviction that he who retards the progress of physiology commits a crime against mankind.”
Although Darwin put his weight behind animal research, it was his theory of evolution that muddied the moral waters by undermining the views of the seventeenth-century French philosopher René Descartes. Descartes believed that animals are biological robots and their behaviors mere reflexes. Thus scientists can slash and burn as they wish. This perspective was exemplified by the nineteenth-century French physiologist Claude Bernard, who wrote, “The physiologist is not an ordinary man: he is a scientist, possessed and absorbed by the scientific idea he pursues. He does not hear the cries of animals, he does not see their flowing blood, he sees nothing but his idea, and is aware of nothing but an organism that conceals from him the problem he is trying to resolve.”
Darwin pointed out that if humans and other animals are similar in our anatomy and physiology, we also share similar mental experiences. Most modern ethologists agree. The list of psychological traits that other species share with humans is growing. Scientists have reported that elephants grieve their dead, monkeys perceive injustice, and cockatoos like to dance to the music of the Backstreet Boys. The ethical consequences of Darwin’s notion that the mental capacities of humans and animals differ by degree rather than kind are inescapable. If animals have perceptions, memories, emotions, and intentions, if they can feel pain and suffer, if they dance, how can we justify using chimpanzees or dogs or even mice in experiments? Is it simply a matter of might makes right?
Thus animal researchers face a conundrum. Often, the more similar a species is to humans, the more useful it is as model for our afflictions. Because chimpanzees share about 98% of their genes with humans, they offer a better model for some human disorders than mice do. But because chimps are so similar to us, their use in research is especially problematic. In other words, often the more justified the use of a species is scientifically, the less justified is its use morally. This is the paradox of Darwin’s legacy.
Animal activists sometimes claim that modern scientists are no different than their eighteenth-century counterparts in believing that animals do not feel pain. For example, in his book Dominion: The Power of Man, the Suffering of Animals, and the Call to Mercy, Matthew Scully, who served as special assistant to former president George W. Bush, writes, “It remains the working assumption of many if not most animal researchers that their subjects do not experience conscious pain or, for that matter, conscious anything else.” Scully is wrong. For an article I was writing on animal consciousness, I once asked fourteen animal researchers if they thought mice were capable of experiencing pain and suffering. All of them said yes when it came to pain, and twelve felt that mice could suffer. In a more systematic survey of British scientists, all but two of 155 animal researchers said that animals experienced pain.
Because most animal researchers do not view animals as biological robots, they do not get off the ethical hook as easily as their nineteenth-century predecessors did. My friend Phil is an example. He studies how cells make use of glucose and fatty acids, the fuels they need to do their jobs. Phil is a basic researcher, but he hopes that his studies might someday lead to treatments for metabolic disorders such as diabetes. I asked Phil if he ever felt guilty about using mice for his experiments. Only once, he said.
Phil had been a member of a research team that was using knockout mice to discover how cells use energy. Knockout animals are genetically engineered so that some of their genes are turned off. Phil’s group was using a knockout line of mice to show that a protein called a transporter helped fatty acids and glucose cross into muscle cells, where they could be used as fuel. Because the transporter gene was inactivated in the knockout mice, the researchers predicted that they would tire more quickly than normal animals.
Phil was charged with measuring how long it took the mice to run out of gas. One way to measure fatigue in rodents is to see how long they can swim. The problem is that air gets trapped in a mouse’s fur so they can float around forever, like a kid lying on an air mattress in a pool. “You have to make them swim for their lives,” Phil told me. The solution is to rig up a miniature harness with just enough weight so that the mouse has to swim to keep his head above water.
Phil learned the procedure from a researcher who worked in another lab. First, take a four-inch-diameter graduated cylinder and fill it with water to within a couple of inches from the top. Then strap the mouse in the weighted harness, lower him into the water, and start the timer. After swimming a few minutes, the mouse will begin to tire. He will start to sink but then he will fight his way to the surface for a gulp of air. The trick is to let the test continue until it is clear that the animal is going down for good. Then quickly grab the beaker and dump out the water before the mouse drowns. The guy who taught Phil this procedure admitted that a couple of his animals did not make it.
Phil only tested one mouse.
He told me, “At some point I could tell that the mouse knew the score, that he had said to himself, ‘OK. I know I am going to die, and I just can’t do it anymore.’ I was supposed to let the test continue to the point where the mouse gives up and sinks and does not try to fight anymore. I dumped the water out and the mouse just lay there panting. He was so exhausted.”
Phil had had enough. He told the professor he was working for that he would not take part in the study. The task of administering the swim test was reassigned to one of the new graduate students.
Like most scientists who use mice as models of fundamental biological processes, Phil neither likes nor dislikes them. They just happened to be the best animals for him to use in order to learn how muscle cells operate. Phil has killed a lot of mice over the years with no remorse. Some by cervical dislocation (he holds their heads down with the blunt side of a pair of heavy scissors and breaks their necks by yanking their bodies backward), others by decapitation (there was a mouse guillotine in lab he worked in; it looks like a miniature paper cutter).
But when push came to shove, Phil was no Cartesian. He looked a drowning mouse in the eye and saw a creature with a will to live. “The part that bothered me was that the mouse had given up, that the mouse knew it was going to die. I would have loved to be able to do the experiment, to measure their muscle fatigue. But I could not do it. I didn’t want to test their will.”
THE MORAL STATUS OF SPACE ALIENS
AND HANDICAPPED INFANTS:
THE PROBLEM OF MARGINAL CASES
While most scientists do not deny that mice are sentient beings, I expect that most animal researchers don’t spend much time fretting over the morality of their work. But every now and then, something turns your head around. In my case, it was a space alien.
It happened one rainy afternoon when our five-year-old twin daughters were bored and starting to get whiny. To placate them, I drove to the video store and rented the movie E.T.: The Extraterrestrial, Steven Spielberg’s 1982 film about a space alien who becomes stranded in a California suburb. I figured it was just the ticket
to keep them occupied for a couple of hours so I could finish writing an article about some experiments I had recently completed on snake behavior. They were immediately hooked and so was I. I quit working on my research report and watched the movie with them, not knowing that it would it would change the way I thought about the use of animals in science.
You probably know the plot. For most of the film, E.T., who has huge puppy eyes and a heart that glows, runs around Southern California with his new human pal, a boy named Elliott. The film ends when E.T.’s mom shows up to fetch her errant son. In the final scene, Elliott reaches out to E.T., pleading, “Stay?” E.T. wistfully shakes his monstrous head, looks deeply into Elliott’s eyes and croaks, “Come?” But, alas, they both know it is not to be. As E.T. creeps into the flying saucer for the long ride back to the home planet Zork, Elliott blinks back a tear. So do I.
I could not get the movie out of my head. That evening over dinner, I conjured up a perverse new ending that I tried out on Betsy and Katie. I asked them, What if the movie ended differently? E.T. asks Elliott to come back to the home planet with him, and just like in the film, Elliott says no. The extraterrestrial, however, does not take no for answer. Instead, he grabs Elliott by the arm and drags the boy kicking and screaming into the alien spaceship. The doors close and as the movie ends, you hear Elliott shouting “Mommy, help me!” as the ship zooms off into space.
The reason for Elliott’s abduction, I explain to the girls, is that a fatal disease is ravishing the population of Zork. Their scientists have come up with a potential cure, and humans, while not as intelligent as the Zorkians, are so biologically similar that they are good subjects for testing potential treatments. The real reason E.T. was in California was to collect humans for these important studies.
“Betsy, what do you think? Should E.T. use Elliott in painful experiments which could help save millions of Zorkians?”
“No, Daddy, no!!”
“But think about it. Zorkians are a lot smarter than humans. After all, E.T. made a space telephone out of junk, and he has special powers that we humans don’t have. He could even make a dead plant bloom.”
Katie chimed in, “I don’t care, Daddy. It would be wrong for E.T. to put Elliott in a cage and use him for some stupid experiments.”
I was not so sure. Like my daughters, I was repulsed by the specter of Elliott sitting forlornly in the alien animal colony where he is injected with an experimental drug that might save the super-smart Zorkians. But as an animal researcher, I had a problem my daughters did not share. The movie made me realize that the justification for animal experimentation, including my own research, ultimately rests on the premise that organisms with bigger brains have the right to conduct research on creatures with less developed mental capacities. Ergo, E.T. has a perfect right to haul Elliott off to Zork.
Philosophers have a different version of the E.T. dilemma that raises a similar issue. It is called the argument from marginal cases. Our use of animals in research is predicated on the assumption that nonhuman species lack certain abilities that humans possess—complex emotions, or abstract thinking, or the ability to learn language. But what about humans who do not possess these traits? Thousands of children are born each year with severe intellectual impairments that render them permanently incapable of ever saying a sentence or thinking about the moral status of mice. The unfortunate truth is that some people are not nearly as smart as the average chimpanzee and some humans don’t have the mental capacities of a mouse. I cannot see any way to set the moral bar so it is high enough to exclude all nonhuman animals, low enough to include all human beings, and be based on morally relevant traits—the ability to feel pain counts; having two legs does not.
Would it be better to test a drug on an anencephalic infant born with no cerebral cortex, a human infant who is blind, deaf, and incapable of experiencing pain, than on a perfectly healthy mouse? My gut tells me that we should not conduct research on profoundly impaired humans in lieu of animals. But when I posed this question to the philosopher Rob Bass, he wrote back: “My gut delivers a different verdict. It seems obvious to me that research on never-to-be conscious anencephalic children is preferable to making mice suffer.” Many of my students also disagree with me: They want to save the mice and conduct our biomedical experiments on death-row prisoners. That’s the problem with moral intuition.
WHAT CAN WE LEARN FROM MOUSE RESEARCH?
While a few philosophers have actually argued that scientists should conduct research on severely handicapped children, most people would prefer that we use animals like mice. But supporters and opponents of animal research disagree on how much we can learn from mouse research. Geneticists say that mouse research has led to breakthroughs in organ transplantation, immunology, and our understanding of cancer and cardiovascular disorders and the causes of birth defects. They want you to know that fourteen Nobel Prizes in physiology and medicine have been awarded for studies conducted on mice. On the other hand, groups like the National Anti-Vivisection Society and the Physicians Committee for Responsible Medicine claim that studies on mice are worthless because they are hopelessly flawed and are even detrimental to human health.
Like it or not, modern biomedical research is built on the backs of mice—millions of them. As lab animals, mice have a lot going for them. They are fertile, docile, and have fast generation times (one mouse year equals thirty human years). Females become sexually mature when they are only a couple of months old and go into estrus every four or five days. They produce litters of six to eight pups after three weeks of pregnancy and will happily copulate again just two days after they give birth.
There is another reason that mice make good research animals—most people do not get in a twit about their rights. In her book Caring: A Feminine Approach to Ethics and Moral Education, the philosopher Nel Noddings, who believes that ethics are based on interpersonal relationships, explains why she feels no moral obligation to rodents. She writes, “I have not established, nor am I likely ever to establish, a relationship with a rat…I am not prepared to care for it. I feel no relation to it. I would not torture it, and I hesitate to use poisons on it for that reason, but I would shoot it cleanly if the opportunity arose.” Most people feel the same way about mice. A 2009 Zogby survey found that 75% of Americans would gladly kill a mouse that showed up in their house. Only 10% indicated they would try to catch the mouse and release it outside, and no one said they would just let the mouse coexist in their home.
The transformation of the mouse from pest to model organism began in 1902 when a Harvard biologist named William Castle obtained inbred mice from a retired Boston schoolteacher for his studies of animal genetics. Castle was not the first scientist to use mice as subjects. The Austrian monk Gregor Mendel bred mice for his first tentative foray into genetics, only shifting to garden peas after his bishop deemed it unseemly for a man of God to share his living quarters with copulating animals. The laboratory mouse was officially born in 1909 when a student of Castle’s named Clarence Little developed the first purebred line of lab mice. Named DBA for their coat color (dilute brown non-agouti), DBA mice are still used in biomedical research.
Mouse research mecca is the Jackson Laboratory, located in Bar Harbor, Maine. Founded in 1929 by Clarence Little with help from Edsel Ford (son of Henry Ford), it is a rodent factory that produces 2.5 million mice a year—nearly 40 tons of inbred, mutant, and genetically engineered mice. Scientists have their pick of over 4,000 strains of Jax mice, and, if none of them suit your needs, Jackson scientists will genetically engineer a new strain to your specifications. Making mice can be expensive, however. Developing a new strain can take a year and run $100,000. While most Jax mice are shipped out as live animals, researchers with space limitations can order their mice as flash-frozen embryos to be thawed out as needed. The names of the colors of Jax mice remind me of the muted tones on the paint-chip samples at Lowe’s—“misty grey,” “light chinchilla,” “gunmetal.”
The variety
of Jax mouse infirmities is even more impressive than the colors of their fur. Hundreds of strains are afflicted with rare cancers, others are prone to facial deformities, and some are born with malfunctioning immune systems. There are Jax mouse models for defects of vision, hearing, taste, and balance. Jax mice come with high blood pressure, low blood pressure, sleep apnea, and Parkinson’s, Alzheimer’s, and Lou Gehrig’s diseases. Researchers trying to cure infertility have their pick of eighty-eight strains of Jax mice with defective reproductive organs. Then there are the mice that just don’t fit in—obsessive-compulsive, chronically depressed, addiction-prone, hyperactive, and schizophrenic mice.
Animal research advocates emphasize the successes. Liz Hodge of the Foundation of Biomedical Research tells me that without animal research we would not have immunizations for polio, mumps, measles, rubella, or hepatitis. Nor would there be antibiotics, anesthetics, blood transfusions, radiation therapy, open-heart surgery, organ transplants, insulin, cataract surgery, and medications for epilepsy, ulcers, schizophrenia, depression, bipolar disorder, or hypertension. Your pets, she says, would also suffer. We would not have immunizations against rabies, distemper, parvo, or feline leukemia, nor treatments for heartworm, brucellosis, cancer, or canine arthritis.
Mouse researchers claim that almost everything we know about the operation of mammalian genes, including human genes, is rooted in mouse studies. True, the evolutionary paths that led to mice and to men diverged 60 million years ago. My brain weighs 1,500 times more than the brain of the little fellow that lives behind the filing cabinet in my basement office. But while we have different numbers of chromosomes (he has 40; I have 46), we have roughly the same number of genes—22,000, more or less. More important, 99.9% of mouse genes have a known human counterpart.
According to Rick Woychik, president and CEO of the Jackson Laboratory, this makes mice the organism that will allow scientists to develop treatments for killers such as juvenile diabetes, breast cancer, and Alzheimer’s disease. “It is,” says Woychick, “a bench-to-bedside continuum. You start with basic concepts, and then these concepts mature and get translated into clinical concepts and ultimately get delivered as innovative new therapies at the bedside.”
