They don't necessarily live longer. They can - but it's only about 3 or 4 years. Just enough time to get MORE attached to them when they die. And then, when they're ready to die, they stand in the corner of their cages facing the corner. It's really strange. Also, if you put guinea pigs in a cage together they hump each other. All the time. And if they're male/female they produce many offspring. And if they're male/male they fight. And if they're female/female they hump each other anyway.

I loved our guinea pigs, but it's still painful. And man, I'm going to cry like a baby whenever either Lucy or George dies.