Curiosity and Human Instincts

Just a few days back I was reading a book called "GENOME--An autobiography of species". The one thing that got me thinking was a relatively simple question --"Why are humans curious?". Why do we just have to know? From the ancient times our forefathers have been trying to know the unknown, delve into the deespest mysteries of the universe and making efforts to come up with the reasons. Sometimes logical, scientific, backed up with theory and experiments. Sometimes not so logical, based entirely on faith, belief and trust.

Some people have gone to the extent of claiming thaat this Quest of Knowledge is what actually differentiates us from the lower beings, and makes us superior. I have few things to say about this superiority business (in genetic terms) below, but first lets finish what I started. So is Curiosity just another human instinct, in addition to the usual sex and hunger thingies? If this is true then what is it that drives it? Sex is for reproduction, hunger is for survival, what is curiosity for?

You tell a child not to go to a certain place, not to do this, not to do that. The child out of his own curiosity just does the opposite and may even kill himself in doing so. Is this behaviour true of other animals, say puppies, kittens, etc.? Are they as curious?

Ok I have run out of the ennergy to write further. Will complete this very soon. By the way, genetically Bacteria are superior to Humans. Will touch this too, but later.
Its F1 time!!