fascinating” exploration (Elizabeth Kolbert) of how ecosystems are sculpted and sustained by animals eating, pooping, and dying—and how these fundamental functions could help save us from climate catastrophe.If forests are the lungs of the planet, then animals migrating across oceans, streams, and mountains—eating, pooping, and dying along the way—are its heart and arteries, pumping nitrogen and phosphorus from deep-sea gorges up to mountain peaks, from the Arctic to the Caribbean. Without this conveyor belt of crucial, life-sustaining nutrients, the world would look very different.The dynamics that shape our physical world—atmospheric chemistry, geothermal forces, plate tectonics, and erosion through wind and rain—have been explored for decades. But the effects on local ecosystems of less glamorous forces—rotting carcasses and deposited feces—as well as their impact on the global climate cycle,...