> Doesn't it intuitively seem like the life by definition would evolve out of any particular niche - say 1,000 Kilometers under the surface - to other areas? O

> Doesn't it intuitively seem like the life by definition would evolve out of any particular niche - say 1,000 Kilometers under the surface - to other areas? Other areas that are similar, sure. But if you're asserting that we can be confident there are no subterranean mantle-creatures because we don't see any wandering about out here, I don't think it's a good argument, for the same reason we can't go down there ourselves and look