I hope I'm not committing some faux pas replying to such an old thread... There are a bunch of hypotheses about why we have yet to encounter or discover other

I hope I'm not committing some faux pas replying to such an old thread... There are a bunch of hypotheses about why we have yet to encounter or discover other intelligent life in our galaxy/universe (or, more specifically, the Fermi Paradox). Two seem particularly relevant here: (a) 'It is the nature of intelligent life to destroy itself': There is some period of technological development where the odds of self-extinction become extremely high (e.g. the relatively recent development of nuclear weapons... for example...). (b) 'It is the nature of super intelligent life to destroy others': Intelligent species past a certain point of technological capability will destroy other intelligent species as they emerge. A species might undertake such extermination out of expansionist motives or even just rational and prudent self-interest: an intelligent species that has overcome its own self-destructive tendencies might view other advanced species as a potential threat. A highly advanced alien species would also likely be a super-predator (as are humans).