2018年6月大学英语六级听力常考时文：Population Growth

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　　1.What contributed to the first rapid increase in population? The
        　　innovation of ...
        　　2.When did the second jump in population begin from? Perhaps ...
        　　3.What may happen to the present rapid population gronwth if technology
begins to yield fewer innovations? It may ...
        　　The growth of population during the past few centuries is no proof that
population will continue to grow straight upward toward infinity and doom. On
the contrary, demographic history offers evidence that population growth has not
been at all constant. According to paleoecologist Edward Deevey, the past
million years show three momentous changes. The first, a rapid increase in
population around one million B. C., followed the innovations of tool-making and
tool-using. But when the new power from the use of tools has been exploited, the
rate of world population growth fell and became almost stable. The next rapid
jump in population started perhaps 10,000 years ago, when mankind began to keep
herds, plow and plant the earth. Once again when initial productivity gains had
been absorbed, the rate of population growth abated. These two episodes suggest
that the third great change, the present rapid growth, which began in the West
between 250 and 350 years ago, may also slow down when, or if , technology
begins to yield fewer innovations. Of course, the current knowledge revolution
may continue without foreseeable end. Either way — contrary to popular belief in
constant geometric growth — population can be expected in the long run to adjust
to productivity. And when one takes this view, population growth is seen to
represent economic progress and human triumph rather than social failure.