How it Began

Out of Eden sprouted from an obsession, and blossomed into a global odyssey.

For years I’d been collecting news clippings about various alien species; I was fascinated both by the guileless initiative of these organisms and by the ecological havoc that often followed their arrival. Scientists spoke of “the homogenization of the world” as native species, residents of the world’s ecological backwaters, gave way to cosmopolitan organisms; the pressing threat to biological diversity was no longer just bulldozers and pesticides but, in a sense, nature itself. I was also intrigued by the research. A new science, a sort of chaos theory of ecology, was congealing around the study of alien species, with biologists re-examining many longstanding theories about ecosystems; think of the invasion biologist as ecology’s emergency-room physician, deciphering how nature works by watching how it falls apart. Finally, I liked the central paradox: that it was precisely my ability to travel to such far-flung places as Hawaii and Tasmania that makes the spread of alien species possible. The writer Christopher Isherwood once said that “the ideal travel book should perhaps be a little like a crime story in which you’re in search of something.” In Out of Eden even the narrator is complicit.

Notes in hand, I pitched a story about the brown tree snake to The New York Times Magazine and was soon on my way to Hawaii and Guam. Originally from Australia, the snake arrived in Guam fifty years ago and has since eaten virtually every bird on that remote island. Now it has begun appearing in Hawaii — home to 40 percent of the nation’s endangered birds — by hitchhiking in the wheel wells of airplanes. The snake has become the iconic invader, emblematic of the harm that alien species can inflict. It is also a sublimely elegant creature, as I learned one day when my guide handed me a live one. While I held the snake’s pebbly head between my thumb and forefinger, clamping the jaw safely shut, the rest of the snake — all six feet of it — wrapped itself around me and gently, clinically began to squeeze. I lifted its head for a better look into those impassive beady eyes, and we stayed like that for a while, sizing each other up.

At that moment, what I’d imagined would be a straightforward book about harmful alien species blossomed into something far more rich, subtle, and, to my own surprise, personal. For starters, I had some questions. Some years ago, the environmental writer Bill McKibben argued that, with the most far-flung wildernesses now tainted by human-induced global warming, nature, that “separate and eternal” realm untouched by our existence, had ended. But if nature was finished, what now was this thing wrapped around me, doing its best to finish me? Was is it not nature? Was I not nature? What, in this rapidly changing world, is nature? Between the realms of pure nature and of pure people, there lies a vast, edifying gray zone — filled, it seemed to me, with alien species.

Most books about ecological invasion paint the subject in black-and-white terms, as a stark choice between bad species (invaders) and good ones (natives). That seemed unfair to me, and inaccurate. After all, alien species are biogeographical winners; they represent nature at its fittest, spreading and succeeding — even if we don’t always appreciate the outcome. Instead of demonizing these globe-trotting organisms, I wanted to present them in a more neutral light. I wanted to give myself, and by extension the reader, permission to be impressed by them, to admire their victories — to sympathize with them, even.

For the fact is, alien species do not come from Mars; they are not “other.” They are very much of us, by us; humans are the main agent of their spread. Some organisms, like the brown tree snake, are accidental travelers, incidental to our own movements around the world. But many more — from kudzu to starlings, not to mention our lawn grasses and our food system, which is made up almost entirely of alien species — come expressly at our invitation. We like aliens. We may not like what they do when they escape our immediate control. But only by appreciating alien species — acknowledging their appeal, which is what draws them into our company in the first place — can we begin to understand the true nature of the threat they pose.

I like to think of my book as a kind of parable, simultaneously cautionary and celebratory — a travel book about the natural consequences of travel. It is a search both for scientific answers and for ecological identity. Put another way, Out of Eden is about what the best journeys are ultimately about: our native origins, or rather, our home — the struggle to find it, to attain it and, finally, to go about beginning to live in it. I hope you enjoy the story.