Thursday, November 25, 2004

Conflagration -- the european invasion of the americas

The New York Times > Opinion > Charles Mann: Unnatural Abundance is an astounding NYT essay by Charles C. Mann, author of the forthcoming "1491: New Revelations of the Americas Before Columbus." The key observations are that, from an ecological perspective, the native american peoples were but one of large number of native "species" annihilated by the european invaders, and that those invaders that as much microbe and plant as human.

He doesn't mention dogs. There were dogs in the americas before the european invasion, but we know from recent gene studies that none survived. It would be interesting to know what killed them all. I suspect it was a pathogen that european dogs had adapted to.

Why were the microbial attacks so one sided? Europeans has spent hundreds of years in cesspools of festering disease -- cities. Plagues were commonplace. European immune systems were well tuned to the a wide range of pathogens. Native americans, living in a far healthier environment, had none of these adaptations. (I wonder how the anti-evolutionists explain the death of the native americans -- do they thing God did it?) Even to this day, euros are relatively resistant to HIV.

The essay sheds new light on how the Pilgrims survived. It had always seemed strange that such an ill-planned expedition should survive a northern winter. It turns out the plague had prepared their rations. I doubt Mrs. Cheney (famed for her campaign to teach mythology in place of history) would approve.
November 25, 2004
Unnatural Abundance

... Until the arrival of the Mayflower, continental drift had kept apart North America and Europe for hundreds of millions of years. Plymouth Colony (and its less successful predecessor in Jamestown) reunited the continents. Ecosystems that had evolved separately for millennia collided. The ensuing biological tumult - plants exploding over the landscape, animal species spiking in population or going extinct...

In a phenomenon known as "ecological release," imported species can run wild because their natural predators have not come along with them. Clover and bluegrass, tame as accountants at home, transformed themselves into biological Attilas in the Americas, sweeping through vast areas so fast that the first English colonists who pushed into Kentucky found both species waiting for them. The peach proliferated in the Southeast with such fervor that by the 18th century, the historian Alfred Crosby writes, farmers feared that the Carolinas would become a wilderness of peach trees.

South America was just as badly hit. Endive and spinach escaped from colonial gardens and grew into impassable, six-foot thickets on the Peruvian coast; thousands of feet higher, mint overwhelmed Andean valleys. In the pampas of Argentina and Uruguay, the voyaging Charles Darwin discovered hundreds of square miles strangled by feral artichoke. "Over the undulating plains, where these great beds occur, nothing else can live," he observed.

... Wheat, following bluegrass and clover, occupied huge swathes of the Midwestern savanna. Meanwhile, corn conquered Africa, Asia and central Europe. Corn so thrived in 16th- and 17th-century Africa, Dr. Crosby has argued, that it sustained a population explosion that let Europeans take millions of Africans for slaves without emptying the continent.

... Soon after Europeans arrived, European diseases killed 90 percent or more of the hemisphere's original inhabitants - at least 30 million people, and possibly 100 million, according to most recent estimates.

Four years before the Pilgrims' arrival, shipwrecked French sailors accidentally unleashed an epidemic, possibly viral hepatitis, on Cape Cod, which then swept through New England. The Pilgrims moved into an Indian village, Patuxet, that had been emptied by disease; they survived the first winter only after digging up food caches in victims' houses and graves...

... American Indians were ambitious, sophisticated landscape managers. In South America, they drained vast areas of wetland; scattered networks of raised agricultural fields in Bolivia, Colombia and the Guianas; and converted much of Amazonia into an "anthropogenic" forest - a mix of gardens, orchards and agricultural forests. Visitors to the Andes still gawp at the Indian terraces that carpet the highlands - more than 2,000 square miles of them in Peru alone, according to the geographer William M. Denevan, most of them at more than 9,000 feet.

Above the Rio Grande, Indians' principal land-management tool was fire, used to create and maintain open, game-friendly forests and grazing lands. Native pyromania created a third or more of the Midwestern prairie; fire kept Eastern forests so open that the first European colonists reported being able to ride through the woods in carriages. In California, Oregon, Texas and a hundred other places, Indian burning governed the conditions under which other species thrived or failed.

When disease carried away native societies, the torches went out. Trees and underbrush erupted in ways that had not been seen for millennia, filling in areas kept open by Indian axes and Indian fire. "Almost wherever the European went, forests followed," wrote the ecological historian Stephen Pyne. Far from destroying wilderness, in other words, European settlers created it - only it was a peculiar, unprecedented kind of wilderness, shot through with European invaders and characterized by population outbreaks from species that had formerly been uncommon...

...Other researchers have made similar arguments for bison, elk and moose. All were kept down by Indians - the big mammals by hunting, the pigeon because Indians both ate it and competed with it for the nuts on which it depended. The huge herds and flocks seen by Europeans were evidence not of American bounty but of Indian absence...

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