Charles C. Mann
1491: New revelations of the America’s before Columbus
Adapted from pages 342-343
What happened after Columbus’s arrival was like a thousand kudzus everywhere.
Throughout the hemisphere ecosystems cracked and heaved like winter ice. Echoes of the
biological tumult resound through colonial manuscripts. Colonists in Jamestown broke
off from complaining about the depredations of the rats they accidentally imported. Not
all the invaders were such obvious pests, though. Clover and bluegrass, in Europe as tame
and respectable as accountants, in the Americas transformed themselves into biological
Attilas, sweeping through vast areas so quickly that the first English colonists who
pushed into Kentucky found both species waiting for them. Peaches, not usually regarded
as a weed, proliferated in the southeast with such fervor that by the eighteenth century
farmers feared that the Carolinas would become “a wilderness of peach trees.”
South America was hit especially hard. Endive and spinach escaped from colonial
gardens and grew into impassible, 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
now live,” he observed.
A phenomenon much like ecological release can occur when a species suddenly
loses its burden of predators. The advent of mechanized fishing in the 1920s drastically
reduced the number of cod from the Gulf of Maine to the Grand Banks. With cod gone,
the urchins on which they fed had no enemies left. Soon a spiny carpet covered the
bottom of the gulf. Sea urchins feed on kelp. As their population boomed, they destroyed
the area’s kelp beds, creating what icthyologists call “sea urchin barrens.”
In this region, cod was the species that governed the overall composition of the
ecosystem. The fish was a “keystone” species: one “that affects the survival and
abundance of many other species,” in the definition of Harvard biologist Edward O.
Wilson. Keystone species have disproportionate impact on their ecosystems. Removing
them, Wilson explained “results in a relatively significant shift in the composition of the
[ecological] community.”
Until Columbus, Indians were a keystone species in most of the hemisphere.
Annually burning undergrowth, clearing and replanting forests, building canals and
raising fields, hunting bison and netting salmon, growing maize, manioc, and the Eastern
Agriculture Complex, Native Americans had been managing their environment for
thousands of years. While they occasionally made mistakes they were able to modify
their landscapes in stable, supple, resilient ways. Some areas have been farmed
successfully for thousands of years. Even the wholesale transformation, as seen in places
like Peru, where irrigated terraces cover huge areas, were exceptionally well done. But all
these efforts required close, continual oversight. In the sixteenth century, epidemics
removed the boss.
American landscapes after 1492 were emptied. Suddenly deregulated, ecosystems
shook and sloshed like a cup of tea in an earthquake. Not only did invading endive and
rats beset them, but native species too, burst and blasted, freed from constraints by the
disappearance of Native Americans. The forest that the first New England colonists
thought was primeval and enduring was actually in the midst of a violent change and
demographic collapse. So catastrophic and irrevocable were the changes that it is
tempting to think that almost nothing survived from the past. This is wrong: landscape
and people remain, though greatly altered. And they have lessons to heed, both about the
earth on which we all live, and about the mental frames we bring to it.