Increasingly, historians are blaming diseases imported from the Old World for the staggering disparity between the indigenous population of America in 1492—new estimates of which soar as high as 100 million, or approximately one-sixth of the human race at that time—and the few million full-blooded (full-blooded) Native Americans alive at the end of the nineteenth century. There is no doubt that chronic disease was an important factor in the precipitous decline, and it is highly probable that the greatest killer was epidemic disease (epidemic disease: 流行病), especially as manifested in virgin-soil epidemics.
Virgin-soil epidemics are those in which the populations at risk have had no previous contact with the diseases that strike them and are therefore immunologically almost defenseless. That virgin-soil epidemics were important in American history is strongly indicated by evidence that a number of dangerous maladies—smallpox, measles, malaria, yellow fever, and undoubtedly several more—were unknown in the pre-Columbian New World. The effects of their sudden introduction are demonstrated in the early chronicles of America, which contain reports of horrendous epidemics and steep population declines, confirmed in many cases by recent quantitative analyses of Spanish tribute records and other sources. The evidence provided by the documents of British and French colonies is not as definitive because the conquerors of those areas did not establish permanent settlements and begin to keep continuous records until the seventeenth century, by which time the worst epidemics had probably already taken place. Furthermore, the British tended to drive the native populations away, rather than enslaving them as the Spaniards did, so that the epidemics of British America occurred beyond the range of colonists’ direct observation.
Even so, the surviving records of North America do contain references to deadly epidemics among the indigenous population. In 1616-1619 an epidemic, possibly of bubonic or pneumonic plague, swept coastal New England, killing as many as nine out of ten. During the 1630’s smallpox, the disease most fatal to the Native American people, eliminated half the population of the Huron and Iroquois confederations. In the 1820’s fever devastated the people of the Columbia River area, killing eight out of ten of them.
Unfortunately, the documentation of these and other epidemics is slight and frequently unreliable, and it is necessary to supplement what little we do know with evidence from recent epidemics among Native Americans. For example, in 1952 an outbreak of measles among the Native American inhabitants of Ungava Bay, Quebec, affected 99 percent of the population and killed 7 percent, even though some had the benefit of modern medicine. Cases such as this demonstrate that even diseases that are not normally fatal can have devastating consequences when they strike an immunologically defenseless community.
1. The primary purpose of the passage is to
(A) refute a common misconception
(B) provide support for a hypothesis
(C) analyze an argument
(D) suggest a solution to a dilemma（B）
(E) reconcile opposing viewpoints
2. According to the passage, virgin-soil epidemics can be distinguished from other catastrophic outbreaks of disease in that virgin-soil epidemics
(A) recur more frequently than other chronic diseases
(B) affect a minimum of one-half of a given population
(C) involve populations with no prior exposure to a disease
(D) usually involve a number of interacting diseases（C）
(E) are less responsive to medical treatment than are other diseases
3. According to the passage, the British colonists were unlike the Spanish colonists in that the British colonists
(A) collected tribute from the native population
(B) kept records from a very early date
(C) drove Native Americans off the land
(D) were unable to provide medical care against epidemic disease（C）
(E) enslaved the native populations in America
4. Which of the following can be inferred from the passage concerning Spanish tribute records?
(A) They mention only epidemics of smallpox.
(B) They were instituted in 1492.
(C) They were being kept prior to the seventeenth century.
(D) They provide quantitative and qualitative evidence about Native American populations.（C）
(E) They prove that certain diseases were unknown in the pre-Columbian New World.
5. The author implies which of the following about measles?
(A) It is not usually a fatal disease.
(B) It ceased to be a problem by the seventeenth century.
(C) It is the disease most commonly involved in virgin-soil epidemics.
(D) It was not a significant problem in Spanish colonies.（A）
(E) It affects only those who are immunologically defenseless against it.
6. Which of the following can be inferred from the passage about the Native American inhabitants of Ungava Bay?
(A) They were almost all killed by the 1952 epidemic.
(B) They were immunologically defenseless against measles.
(C) They were the last native people to be struck by a virgin-soil epidemic.
(D) They did not come into frequent contact with white Americans until the twentieth century.（B）
(E) They had been inoculated against measles.
7. The author mentions the 1952 measles outbreak most probably in order to
(A) demonstrate the impact of modern medicine on epidemic disease
(B) corroborate the documentary evidence of epidemic disease in colonial America
(C) refute allegations of unreliability made against the historical record of colonial America
(D) advocate new research into the continuing problem of epidemic disease（B）
(E) challenge assumptions about how the statistical evidence of epidemics should be interpreted
8. Which of the following, if newly discovered, would most seriously weaken the author’s argument concerning the importance of virgin-soil epidemics in the depopulation of Native Americans?
(A) Evidence setting the pre-Columbian population of the New World at only 80 million
(B) Spanish tribute records showing periodic population fluctuations
(C) Documents detailing sophisticated Native American medical procedures
(D) Fossils indicating Native American contact with smallpox prior to 1492（D）
(E) Remains of French settlements dating back to the sixteenth century