By 1947, scientists understood the value of inbred mice. That year, the Jackson Laboratory was destroyed in a fire that consumed the town of Bar Harbor, killing 14 people and 90,000 mice. The following day, research institutes and individual geneticists who had acquired mice from the lab began sending back breeding pairs so that Little could re-establish his colonies, says Rader.
Little claimed to have received just one angry letter from an anti-vivisectionist women's club, which suggested it might have been better if he and his scientists had burned instead of the mice. Anti-vivisectionists of the time were largely concerned with cats and dogs. The public's sympathy rarely extended to rodents, which were regarded as vermin and carriers of disease.
The return of the mice paved the way for two important discoveries. George Snell's studies of tumour transplantation and rejection in mice in the late 1940s laid the foundation for modern immunology. Without it, human organ transplants would be impossible. Another of the rebuilt lab's scientists, Leroy Stevens, also made great strides with his own studies of tumour transplantation, which eventually led to the discovery of embryonic stem cells.
The decoding of the mouse genome in 2002 opened up still greater possibilities. We now know that 99 per cent of human genes have a comparable version in mice and many of them are located in the same place on the chromosome. That means scientists can work out the role of any human gene by creating mice lacking the equivalent gene. When the mice exhibit a defect, scientists can pinpoint the gene's function and test treatments.
"Little wouldn't have dreamed about this, but he would have been thrilled," says Rader. Indeed, on his 80th birthday in 1968, Little drew a cartoon of a lab mouse on a pedestal. The drawing shows him looking up at the mouse which says: "You're not so damn smart. You've had 80 years. Look what my family has done in 39 years."