Stephen Hawking recently stated that the human race should refrain from trying to make contact with any alien life out there. Why? Because they just might run us over and take our 'resources', that's why. I think Neil deGrasse Tyson makes a very important observation in this interview:
The assumption that an intelligent, alien race would be as primitively hostile as we have been is based entirely on us looking at ourselves in retrospect, not on tangible, scientific data. Urging us to just hide—at this point—doesn’t seem very constructive. We just won’t know before we’ve made contact, and trying to hide is only going to delay that a little.