Rat-catching, Mumbai, India

Keeping the rat population under control was practiced in Europe to prevent the spread of diseases to man, most notoriously the Black Plague and to prevent damage to food supplies.
Anecdotal reports suggest that some rat-catchers in Europe would raise rats instead of catching them in order to increase their eventual payment from the town or city they were employed by. This, and the practice of rat-fights, could have led to rat-breeding and the adoption of the rat as a pet - the fancy rat.
A famous rat-catcher from Victorian England was Jack Black, who is known through Henry Mayhew's interview for London Labour and the London Poor.