Rats - should we like them? Some people hate and despise these rodents. As the Chinese Year of the Rat draws to a close, down on the farm the rats' year goes on. Resourceful and adaptable, these successful invaders have enjoyed our unwitting hospitality for over two centuries.

But this Jekyll and Hyde of animals challenges our prejudices. Is it not also an attractive pet, and a clever animal; and don't we all owe our lives to the rat as a tool of research into good health? This animal opportunist should be watched - even from behind your chair....