I've seen someone post this before. Again, it doesn't completely dismiss the notion of alien life. It suggests that there might not be, but it also offers explanations as to why we are yet to find any if they are out there somewhere. And remember, it doesn't have to be an advanced form of life. Alien life classifies as any form of life not originally from this planet, whether it be an advanced race beyond our comprehension, or a simplistic species of basic bacterial cells.