"The fact is that what scientists call zoonotic disease was little known in the Americas. By contrast, swine, mainstays of European agriculture, transmit anthrax, brucellosis, leptospirosis, trichinosis, and tuberculosis. Pigs breed exuberantly and can pass diseases to deer and turkeys, which then can infect people. Only a few of De Soto's pigs would have had to wander off to contaminate the forest. The calamity wreaked by the De Soto expedition, Ramenofsky and Galloway argued, extended across the whole Southeast. The societies of the Caddo, on the Texas-Arkansas border, and the Coosa, in western Georgia, both disintegrated soon after. The Caddo had a taste for monumental architecture: public plazas, ceremonial platforms, mausoleums. After De Soto's army left the Caddo stopped erecting community centers and began digging community cemeteries. Between the visits of De Soto and La Salle, according to Timothy K. Perttula, an archaeological consultant in Austin, Texas, the Caddoan population fell from about 200,000 to about 8,500--a drop of nearly 96 percent. In the eighteenth century, the tally shrank further, to 1,400. An equivalent loss today would reduce the population of New York City to 56,000, not enough to fill Yankee Stadium. "That's one reason whites think of Indians as nomadic hunters," Russell Thornton, an anthropologist at the University of California at Los Angeles, said to me. "Everything else--all the heavily populated urbanized societies--was wiped out."