Read the passage from "For More Wonder, Rewild the World." Isn’t it an amazing thought that every time you wander into a park or down an avenue or through a leafy street, you can see the shadows of these great beasts? Paleoecology, the study of past ecosystems, crucial to an understanding of our own, feels like a portal through which you may pass into an enchanted kingdom. And if we really are looking at areas of land of the sort of sizes I’ve been talking about becoming available, why not reintroduce some of our lost megafauna, or at least species closely related to those which have become extinct everywhere? Why shouldn’t all of us have a Serengeti on our doorsteps?