I have a theory I want to share... What if there is intelligent life capable of coming here? Do you honestly believe that they want to come visit us? I think they'd be afraid we'd either A) Shoot on sight (I mean really, look at our movies), B) Capture them and "probe" them- the government would love to see what makes them tick, or C) Try and fork them (See Captain Kirk). Plus I don't think we'd be invited to the intergalactic assembly when they find out some teenager threw her newborn baby into a dumpster.