I just don't think the word "purpose" is used correctly when we speak of reproduction as atheists. Who's purpose? We have no "purpose" other than the one we choose. Saying that our purpose is to reproduce can be interpreted as: we were put here for something. We survive, because we reproduce. This happens naturally. No purpose. I hope that I'm explaining myself well.
"Hipster is what happens when young hot people do what old ladies do." -Exian