单选题
When the world was a simpler place, the rich were
fat, the poor were thin, and right-thinking people worried about how to feed the
hungry. Now, in much of the world, the rich are thin, the poor are fat, and
right-thinking people are worrying about obesity. Evolution is
mostly to blame. It has designed mankind to cope with deprivation, not plenty.
People are perfectly tuned to store energy in good years to see them through
lean ones. But when bad times never come, they are stuck with that energy,
stored around their expanding bellies. Thanks to rising
agricultural productivity, lean years are rarer all over the globe. Modernday
Malthusians, who used to draw graphs proving that the world was shortly going to
run out of food, have gone rather quiet lately. According to the UN, the number
of people short of food fell from 920m in 1980 to 799m 20 years later, even
though the world's population increased by 1.6 billion over the period. This is
mostly a cause for celebration. Mankind has won what was, for most of his time
on this planet, his biggest battle: to ensure that he and his offspring had
enough to eat. But every silver lining has a cloud, and the consequence of
prosperity is a new plague that brings with it a host of interesting policy
dilemmas. As a scourge of the modern world, obesity has an
image problem. It is easier to associate with Father Christmas than with the
four horses of the apocalypse. But it has a good claim to lumber along beside
them, for it is the world's biggest public-health issue today—the main cause of
heart disease, which kills more people these days than AIDS, malaria, war; the
principal risk factor in diabetes; heavily implicated in cancer and other
diseases. Since the World Health Organisation labelled obesity an "epidemic" in
2000, reports on its fearful consequences have come thick and fast.
Will public-health warnings, combined with media pressure, persuade
people to get thinner, just as they finally put them off tobacco? Possibly. In
the rich world, sales of healthier foods are booming (see survey) and new
figures suggest that over the past year Americans got very slightly thinner for
the first time in recorded history. But even if Americans are losing a few
ounces, it will be many years before the country solves the health problems
caused by half a century's dining to excess. And, everywhere else in the world,
people are still piling on the pounds. That's why there is now a consensus among
doctors that governments should do something to stop them.
单选题
The author write this passage mainly to ______.