First broadcast June 2005
For some, rats are a disease carrying pest. On the other hand, they have long been used to fight human problems.
And rats are also regarded as a tasty source of protein in some cultures.
Mark Lewis builds up a portrait of the relationship between man and one of our oldest camp followers.
Part 1: New York
New York, city of skyscrapers but also of hundreds of miles of sewers, has been described as "Ratropolis".
Hear from New Yorkers who tell us how, for them, rats are symbols of something dirty and fearful - but are also able to tell them something about themselves as humans.
When they surface in an apartment, people panic and call rat exterminators. Rat extermination is good business in New York - and rat exterminators like Jack Wiler cater to psychological as well as practical needs.
Some, like the journalist Bob Sullivan who spent a year of nights watching rats in an alley in downtown Manhattan, feel the need to face up to the fear of rats, and to look into their own psyche in the process.
But for New Yorkers, the fear remains - symbolized by the link between rats and plague.
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