The risks are twofold: probes sent from Earth may contaminate Mars with terrestrial bacteria, wrecking future studies of Martian life; or, more important, bacteria brought back from Mars may contaminate the Earth with unpredictable effects.
This sentence is a perfect
example of why were going to fuck something up royally if we ever discover extraterrestrial life.
It's not "more
important", you assholes! It's "AS
important"!! The Martian life-forms are just up there doin' there thing.. It's just as important that we don't screw them
over as they don't screw us
over. Of course, I'm not aware of any measures taken to ensure that Earthly bacteria didn't arrive on Mars with one of our probes..
Earthlings need to understand that we're simply not the most important
"I want my lamp back. I'm gonna need it to get out of this slimy mudhole."
I'm not even angry. I'm being so sincere right now, even though you broke my heart and killed me.