| Three of your possibilities are "locations" for the Great Filter, as I read them: > Intelligent life is far more of an aberration than we realise. The filter is between "smart mammal" -> "human-level smarts." So there's lots of planets with lions, tigers and bears, but not talking dinos (or whatever). > Intelligent life is actually very dumb on a macro scale, and falls prey to Malthusian collapse, either by falling into a significant energy gap or by destroying their biosphere. The filter is between "21st century humanity" and "interplanetary/interstellar civilization." The universe is full of ruined planets, noticable because they've got transuranic elements floating around they shouldn't have. > Intelligent life tends to succumb to dysgenic fertility, and ceases to be intelligent. The filter is somewhere between "human-level smarts" and "interplanetary civilization." The universe is full of Morlocks. We want the filter to be behind us. If it's actually "life is nearly impossible" then we're golden. Life on Mars 'pushes' the possible 'locations' of filter further forward (so life is probably common). If it's multicellular life, that pushes the filter further again, etc. |