Maybe this issue had been raised and Mankind was as Tootired suggests, the test to answer the question raised previous to mans creation.
See, I have often wonedred how fortuitous it was, that Satan tempted Adam and Eve before they had any kids, imagine the senario if they had a couple of kids first, then sinned and the kids didnt, we would have half the world as we are now, and the other half consisting of 7000 year old perfect people who wouldnt have been able to talk to us in case they learnt our bad ways.
So it had to have kicked off right from the start, just like a tesy that had been prearranged.
Either that or God moved all the perfect people to live inside a "Hollow Earth" and now they come visit us in their flying saucers?