The rodents' PR problem helps explain how they came to infest science and medicine in the first place. C.C. Little, the inventor of the modern lab mouse and founder of the Jackson Laboratory, had long used "the age old enmity of woman and the Muridae" as a sales pitch for his model organism. Writing in American Naturalist in 1939, he noted that "it has been difficult to keep at fever heat a sufficient level of sympathy for the rodent similar to that which the dog or cat engenders." Indeed, when controversy erupted over Pepper's death in 1965, Little's company was quietly supplying physiologists with close to 1 million mice every year. (Today, the sales of rats and mice dominate a $1.4 billion global market in laboratory animals.)
For 100 years or more, scientists and activists had traded blows over the ethics and practice of research on dogs and cats. Through all that back-and-forth, lab rodents were always left just across the moral frontier of live-animal experimentation—close enough to humans to remain a meaningful source of knowledge but not so close that we couldn't slaughter them in droves. Yet it's not obvious—to those who might consider the question—that the welfare of a rat or mouse is any less important than that of a dog. Recent research suggests that the health of mice improves when they're given cage toys, running wheels, and crawl tubes to play with. Rats can learn to respond to a name and recognize individual people. We might quarrel over the inner lives of honeybees or river trout, but is the suffering of our fellow mammals really in question?
Meanwhile, rats and mice are subject to some of the most extreme and invasive experiments in biomedicine. By the early 1980s, we were spiking mouse DNA with cancer-causing genes; a few years later, we started to "knock out" specific lines of genetic code. (Scientists mapped out the entire mouse genome in 2002 and the rat genome in 2004.) We regularly subject rodents to pain, starvation, solitary confinement, and grotesque disfigurement. Whatever misery they endure is multiplied across the hundreds of millions of rats and mice used in labs every year.
The animal-welfare groups have failed in their most ambitious efforts to protect laboratory rodents. "We did and do strongly support the inclusion of rats and mice," says Cathy Liss, current president of the Animal Welfare Institute. "But the question is how can we properly address that? At this juncture, it's premature to go forward and rally support." With rodents off the table, though, it's not clear what's left for the activists to do.