When Anton van Leeuwenhoek made the first recorded estimation of global population in the latter third of the 17th century, he reported the number at 13.85 billion people. Despite this grandiose guess, which was based on Leeuwenhoek's estimation of the amount of inhabitable land worldwide, a number of factors, including drought, disease, famine, high infant mortality, natural disasters, and war, had been keeping the world population far more in check. In fact, Leeuwenhoek was off by several orders of magnitude; the actual population figure for his time is now estimated at about half a billion. Although this number is relatively small compared to the nearly 7 billion people inhabiting the planet today, Leeuwenhoek made his prediction at a time when the population was rapidly expanding.

By 1830, the number of people increased twofold to a billion, and over the next century, the global population doubled again to 2 billion. Since 1930, a tripling of the human population has occurred, thanks to the scientific and technological advancements that have significantly improved life expectancy rates around the world. The developments of modern sanitation and health care practices have been particularly influential in enhancing the average quality and length of human life. Enhanced agricultural techniques provide greater crop yields from even marginal soil, making devastating food shortages a rarity around the globe. Particularly benefitting from these advances are large families in third-world communities, who once suffered high child mortality rates but now see the majority of their children reach adulthood. With each successive generation, the global population grows at a rapid pace.

According to the United Nations, Earth's current population of approximately 7 billion could swell to 10.5 billion by the year 2045; the consequences of such an increase are yet unknown, although some experts predict they are dire. In 1798, English economist Thomas Malthus postulated that the population grows faster than the food supply until war and pestilence balance the numbers, but the only time the world's population actually declined was when the bubonic plague struck Europe in the mid-14th century. Thus far, technology has managed to keep pace with the ever-expanding populace, but whether innovations will continue to keep us ahead of the demands of an enormous global population remains to be seen.

1. It can be inferred from this passage that

A. Anton van Leeuwenhoek was incompetent as a scientist.
B. someone born today will witness a tripling of the world's population.
C. the United Nations only recently began keeping population statistics.
D. the theories of Thomas Malthus will ultimately be proved correct.
E. an ever-expanding population could put a strain on world resources.


2. The author mentions Thomas Malthus's theory in order to

A. provide support for the argument that population expansion is unsustainable.
B. demonstrate that science has kept a predicted population collapse at bay.
C. divert the reader with an improbable but fascinating scientific assertion.
D. illustrate the evolution of thinking on the subject of population expansion.
E. highlight the weaknesses of 18th-century scientific understanding.


3. According to the passage, the factor that has had the greatest impact on population growth since Anton van Leeuwenhoek's time has been

A. plagues and other instances of disease.
B. war and natural disasters.
C. scientific and technological innovation.
D. high infant mortality.
E. the tradition of raising large families in the third world.