Further possible evidence for a Great Filter: A recent paper suggests that as long as the probability of an intelligent species arising on a habitable planet is not tiny, at least about 10^-24 then with very high probability humans are not the only civilization to have ever been in the observable universe, and a similar result holds for the Milky Way with around 10^-10 as the relevant probability. Article about paper is here and paper is here.
Further possible evidence for a Great Filter: A recent paper suggests that as long as the probability of an intelligent species arising on a habitable planet is not tiny, at least about 10^-24 then with very high probability humans are not the only civilization to have ever been in the observable universe, and a similar result holds for the Milky Way with around 10^-10 as the relevant probability. Article about paper is here and paper is here.