The recovery of the Passenger Pigeon, Carolina Parakeet, and Ivory Billed Woodpecker would seem harmless and likely beneficial to the environment. Maybe not Sabre-Toothed Tigers — at least not in my neighborhood.
I don’t know. Things happen, and then other things happen as a consequence. I think we should just let things be, and when we make a big mistake we should just resolve not to make it again instead of playing around that way. We might make another huge mistake trying to ‘fix’ the past one.