As wikipedia instructs, ferrets have probably been domesticated for at least 2,500 years, although ferrets are still illegal in California.
Ferrets have been used in scientific research for years. In 1971, Felicia the Ferret saved the day at the National Accelerator Laboratory, soon to be known as Fermilab, paving the way for discovery of the bottom quark in 1977. Bottomonium, anyone?
At the University of Washington's Institute for Protein Design, ferrets handle many of the administrative tasks related to Foldit. Ferrets are responsible for dragging off the carcasses of old, dead puzzles, and replacing them new ones. (Sometimes new puzzles are slightly gnawed on when they appear.) Ferrets also distribute points for each puzzle, tracking soloist, evolver, and group scores and the associated rankings.
Ferrets are preferred for these tasks since they are able to navigate the miles of pipes that make up the backbone of the Foldit system without getting stuck. Graduate students tend to get wedged, and many of them are afraid of the dark.