Jared Diamond, in Discover (Oct.One-Way Plagues 1992), 500 S. Buena Vista St., Burbank, Calif. 91521.
Less than 200 years after Christopher Colum- rise of agriculture and then of cities, in both the bus set foot in the New World, the native Amer- Old World and the New, provided the "crowd ican population of some 20 million had de- diseases" with a welcome mat. The rise of farm- clined perhaps 95 percent. The main killers ing and cities also put humans in close contact were not swords...