I agree. But here's the conundrum: how you can you ever be sure there isn't life somewhere? From a logistics and logical standpoint, it's impossible. All you can say is "We haven't found life so far" ADD: And are we saying that separately-evolved strains of life should never have interaction with each other unless we can be sure of all of the consequences? Sure, many of the consequences will be catastrophic, but is it better never to leave home or explore? It makes me very sad to realize than many would say yes, it is.

sigh