1491_ New Revelations of the Americas Before Columbus - Charles C. Mann [61]
In the 1990s Black reviewed thirty-six studies of South American Indians. Not to his surprise, he discovered that overall Indians have fewer HLA types than populations from Europe, Asia, and Africa. European populations have at least thirty-five main HLA classes, whereas Indian groups have no more than seventeen. In addition, Native American HLA profiles are dominated by an unusually small number of types. About one third of South American Indians, Black discovered, have identical or near-identical HLA profiles; for Africans the figure is one in two hundred. In South America, he estimated, the minimum probability that a pathogen in one host will next encounter a host with a similar immune spectrum is about 28 percent; in Europe, the chance is less than 2 percent. As a result, Black argued, “people of the New World are unusually susceptible to diseases of the Old.”*11
Actually, some Old World populations were just as vulnerable as Native Americans to those diseases, and likely for the same reason. Indians’ closest genetic relatives are indigenous Siberians. They did not come into substantial contact with Europeans until the sixteenth century, when Russian fur merchants overturned their governments, established military outposts throughout the region, and demanded furs in tribute. In the train of the Russian fur market came Russian diseases, notably smallpox.
The parallels with the Indian experience are striking. In 1768 the virus struck Siberia’s Pacific coast, apparently for the first time. “No one knows how many have survived,” confessed the governor of Irkutsk, the Russian base on Lake Baikal, apparently because officials were afraid to travel to the affected area. A decade later, in 1779, the round-the-globe expedition of Captain James Cook reached Kamchatka, the long peninsula on the Pacific coast. The shoreline, the British discovered, was a cemetery. “We every where met with the Ruins of large Villages with no Traces left of them but the Foundation of the Houses,” lamented David Samwell, the ship’s surgeon. “The Russians told us that [the villages] were destroyed by the small Pox.” The explorer Martin Sauer, who visited Kamchatka five years after Cook’s expedition, discovered that the Russian government had at last ventured into the former epidemic zone. Scarcely one thousand natives remained on the peninsula, according to official figures; the disease had claimed more than five thousand lives. The tally cannot be taken as exact, but the fact remains: a single epidemic killed more than three of every four indigenous Siberians in that area.
After a few such experiences, the natives tried to fight back. “As soon as [indigenous Siberians] learn that smallpox or other contagious diseases are in town,” the political exile Heinrich von Füch wrote, “they set up sentries along all the roads, armed with bows and arrows, and they will not allow anyone to come into their settlements from town. Likewise, they will not accept Russian flour or other gifts, lest these be contaminated with smallpox.” Their efforts were in vain. Despite extreme precautions, disease cut down native Siberians again and again.
After learning about this sad history I again telephoned Francis Black. Being genetically determined, Indian HLA homogeneity cannot be changed (except by intermarriage with non-Indians). Did that mean that the epidemics were unavoidable? I asked. Suppose that the peoples of the Americas had, in some parallel world, understood the concept of contagion and been prepared to act on it. Could the mass death have been averted?
“There have been lots of cases where individual towns kept out epidemics,” Black said. During plague episodes, “medieval cities would barricade themselves behind their walls and kill people who tried to come in. But whole countries—that’s much harder. England has kept out rabies. That’s the biggest success story that comes to mind, offhand. But rabies is primarily an animal disease, which