O beautiful for spacious skies

"The American frontier" - To most, that phrase conjures up Hollywood images of far-reaching plains, covered wagons, and skittery tumbleweeds. But according to a new book by Tim Flannery, this is only one of the most recent incarnations of the North American frontier.

In fact, the "frontier" Flannery describes has been reinventing itself for millenniums, beginning with the Chicxulub asteroid that struck Earth more than 65 million years ago. It's given birth to lineages (horses, dogs, camels) that emigrated either to reappear thousands of years later, or to disappear altogether. More frequently, it has accepted newcomers and given them ample opportunity to flourish.

With a history that personifies the Statue of Liberty's "huddled masses," the North American continent is what Flannery calls, "a land of immigrants."

In "The Eternal Frontier: An Ecological History of North America and Its Peoples," Flannery - a paleontologist and the director of the South Australian Museum - describes a continent that is continually recreating itself.

"As opposed to the situation on most continents," he writes, "the deep past seems to leave a limited legacy in North America. Change, in the form of climatic shifts and massive immigration, has reshaped the continent's ecology continuously. It is as if the continent knows no rest, no equilibrium, no consistent state to which we can point and say, 'Ah, see, that is North America.' "

The reasons behind its inconsistency, he says, are its geography, geological history, and climate, which have conspired to create a continent unequaled in its schizophrenia. Its funnel-like shape and its north-south mountain ranges create what the author calls a "climatic trumpet," which not only magnifies the smallest temperature changes to create exaggerated seasons, but over the longer term promotes a continental shift from greenhouse to icehouse modes.

Flannery argues that North America's inhabitants have also played an integral part in shaping the continent. The "megafauna" - large animals like mammoths, mastodons, bison, and buffalo - while all immigrants, helped foster the continent's great plains and Alaskan tundra.

When these animals decreased, the land again began to change. Humans continued to flood over the continent, and true to Flannery's description of North America as an eternal frontier, "each successive wave of human invaders found their niche in a more marginal part of North America."

Once humans thrust themselves into the picture, the dynamics were forever changed.

When people started interacting with megafauna and climate, a land that had been reinventing itself every few million years began changing at a more observable pace: People began to settle the land, cut down its forests, destroy its inhabitants (passenger pigeons, bison, and humans alike), and disrupt the continent's delicate balance.

From a non-paleontologist perspective, the first 150 pages of "The Eternal Frontier" are anything but gripping, although the facts they provide are important to understanding North America's mutable nature. Unlike Flannery's previous book, "Throwim Way Leg," the subject does not lend itself to an easy narrative. The scope of his story is huge, and his research exhaustive, but even Flannery cannot make a dry subject completely compelling.

The last half of the book, however, makes for a good read. It's here that Flannery drives his point home, and here that the true significance of his frontier theory becomes clear: The history of the land has influenced America's politics. "What is most worrying about this dismal history," he writes, "is that on the frontier, ruthless exploitation, greed and senseless environmental destruction had become an honored tradition. All of the US's defenses, both political and social, were traduced by the vast wealth and influence won by the rapers of the land."

It's enough to make this reader want to trade the safety of her superpower government for the sound of a passenger pigeon flying overhead.

Lauren Gravitz is a freelance science writer living in Cambridge, Mass.

(c) Copyright 2001. The Christian Science Monitor