Catastrophic Depopulation and the Columbian Exchange: A Selection from Charles C. Mann’s 1491 (2005)

“If time travelers from today were to visit North America in the late Pleistocene, they would see in the forests and plains an impossible bestiary of lumbering mastodon, armored rhinos, great dire wolves, sabertooth cats, and ten-foot-long glyptodonts like enormous armadillos. Beavers the size of armchairs; turtles that weighed almost as much as cars; sloths able to reach tree branches twenty feet high; huge, flightless, predatory birds like rapacious ostriches—the tally of Pleistocene monsters is long and alluring.

At about the time of Clovis almost every one of these species vanished. So complete was the disaster that most of today’s big American mammals, such as caribou, moose, and brown bear, are immigrants from Asia. The die-off happened amazingly fast, much of it in the few centuries between 11,500 and 10,900 B.C. And when it was complete, naturalist Alfred Russell Wallace wrote, the Americas had become ‘a zoologically impoverished world, from which all of the hugest, and fiercest, and strangest forms [had] recently disappeared.’

The extinctions permanently changed American landscapes and American history. Before the Pleistocene, the Americas had three species of horse and at least two camels that might have been ridden; other mammals could have been domesticated for meat and milk. Had they survived, the consequences would have been huge. Not only would domesticated animals have changed Indian societies, they might have created new zoonotic diseases. Absent the extinctions, the encounter between Europe and the Americas might have been equally deadly for both sides—a world in which both hemispheres experienced catastrophic depopulation.”—Charles C. Mann, 1491: New Revelations of the Americas Before Columbus (2005)