Who are we? Really as a whole.

I thought about this for a while and it struck me the other day, why are we here? On this planet? And not any other planet. We could have been easily adapted to live on any planet. I guess this is one of those questions that if you are a religiuos person, you will have to wait unil the end of your life to find the answers to the quetion. Myself, personally, I will be waiting for my death to find the answers. Now for those who are scientific minded, the question goes to you, answer it if you can!!