  In college, a professor once assigned a project for me in which I was to answer the question of what life will be like after humans populate Mars. I finally came down to one conclusion: that colonies on Mars are humans' only chance for peace on Earth because only then would humans have a common other by which they could define themselves and a common enemy against whom they would unite.
Of course, peace on Earth would be rather hallow in light of interplanetary hostilities. Two very smart individuals, Professor Seth Shostak, a senior astronomer at the SETI institute, and Alex Barnett, chief executive office of the Chabot Space Centre, have come together to write a book called urlLink Cosmic Company , which urlLink concludes dramatically that we Earthlings should almost (statistically speaking) certainly come into contact with another planet's civilization by 2025.
Peter Bishop would call this a wild card event, that is, something with a very small probability of occurring, but with amazing, off the chart consequences. It astounds the mind to just consider this happening in our lifetime. But my predictions for the way we humans would interact with Martians, even Martians of our own progeny, carries over to interactions with aliens. For the aliens' sake, I sure hope we don't find them. 
