Michael Soule explains that fragmentation also means the end of evolution for large vertebrates and plants (read trees). There is not enough room for existing species to split into new ones. So as existing species go extinct, from even the most natural of causes, none will be replaced. Earth itself is an island with no immigration.
Terminology has changed over the years. What was once "island biogeography" is now "population viability." Today there are scientists who call themselves "conservation biologists," who are being sought out by managers of public lands to solve Solomonic problems. The ultimate goal for conservation, Lovejoy says, is "intact, fully diverse ecosystems persisting in reserves." Whether any reserve in the world is actually large enough is not now known.
Nothing is perfect. One or two sections of the book are extraneous. Occasional coarse language jars by its contrast with the rest. The author can be coy, as when he bids us to close our eyes while he uses an equation, or when he tells us to relax because he is not going to burden us with pages and pages of details about a list he has just given. But on the whole it's a book that's going to be read for many years to come, even though it's too big to carry around as Quammen has toted Wallace's The Malay Archipelago for so many years.
The book ends back in Indonesia. Quammen has come to the remote islands of Aru, where Wallace once spent miserable weeks, feet rotting in the rain, trying to collect enough specimens, and thereby earn enough money, to keep going. Have the Aru islands been ecologically destroyed? Not yet. "There's still time," he writes. "If time is hope, there's still hope."
Whatever you do, don't skip to the end. Unless you have read all that leads up to it, you won't feel the full surge of joy in discovering what Quammen finds on Aru, the surge that brought me to my feet.
John P. Wiley jr. is a member of Smithsonian's Board of Editors.