For millennia, lions, tigers, and their man-eating kin have kept our dark, scary forests dark and scary, and their predatory majesty has been the stuff of folklore. But by the year 2150 big predators may only exist on the other side of glass barriers and chain-link fences. Their gradual disappearance is changing the very nature of our existence. We no longer occupy an intermediate position on the food chain; instead we survey it invulnerably from...