Life before life on earth Is there any reference in Buddhism about how our life was before life has appeared on this earth? Were we all in heaven or hell realms?
I suggest you take a look at the Dhammapada which is part of the Pali Canon if you are interested in Buddhism. 

The Buddha taught that such questions weren't important. He rather encouraged people to focus on the life here and now. There are a few dialogs in the Pali Canon in which Buddha answers his apprentice's similar question with a metaphor.