It's not about intelligent life per se; rather the more advanced life we find, the more concerning for the future it would be, as the likelihood of a great filt

It's not about intelligent life per se; rather the more advanced life we find, the more concerning for the future it would be, as the likelihood of a great filter being located ahead of us increases, precisely because we haven't been able to detect more advanced life forms than us. Another interesting consideration is the Dark Forest, of course. I dug out the section in Bostrom's paper: "What has all this got to do with finding life on Mars? Consider the implications of discovering that life had evolved independently on Mars (or some other planet in our solar system). That discovery would suggest that the emergence of life is not a very improbable event. If it happened independently twice here in our own back yard, it must surely have happened millions times across the galaxy. This would mean that the Great Filter is less likely to occur in the early life of planets and is therefore more likely still to come. If we discovered some very simple life forms on Mars in its soil or under the ice at the polar caps, it would show that the Great Filter must exist somewhere after that period in evolution. This would be disturbing, but we might still hope that the Great Filter was located in our past. If we discovered a more advanced life‐form, such as some kind of multi‐cellular organism, that would eliminate a much larger stretch of potential locations where the Great Filter could be. The effect would be to shift the probability more strongly to the hypothesis that the Great Filter is ahead of us, not behind us. And if we discovered the fossils of some very complex life form, such as of some vertebrate‐like creature, we would have to conclude that the probability is very great that the bulk of the Great Filter is ahead of us. Such a discovery would be a crushing blow. It would be by far the worst news ever printed on a newspaper cover."