问答题
What is making the world so much older? There are two
long-term causes and a temporary blip that will continue to show up in the
figures for the next few decades. {{U}} {{U}} 11 {{/U}}
{{/U}}{{U}}The first of the big causes is that people everywhere are living far
longer than they used to, and this trend started with the industrial revolution
and has been slowly gathering pace{{/U}}. In 1900 average life expectancy at birth
for the world as a whole was only around 30 years, and in rich cotmtries under
50. The figures now are 67 and 78 respectively, and still rising. For all the
talk about the coming old-age crisis, that is surely something to be grateful
for-especially since older people these days also seem to remain healthy, fit
and active for much longer. {{U}} {{U}} 12
{{/U}} {{/U}}{{U}}A second, and bigger, cause of the ageing of societies is that
people everywhere are hang far fewer children, so the younger age groups are
much too small to counterbalance the growing number of older people.{{/U}} This
trend emerged later than the one for longer lives, first in developed countries
and now in poor countries too. In the early 1970s women across the world were
still, on average, having 4.3 children each. The current global average is 2.6,
and in rich countries only 1.6. {{U}} {{U}} 13 {{/U}}
{{/U}}{{U}}The UN predicts that by 2050 the global figure will have dropped to just
two, so by mid-century the world's population will begin to level out{{/U}}. The
numbers in some developed countries have already started shrinking. Depending on
your point of view, that may or may not be a good thing, but it will certainly
turn the world into a different place. The temporary blip that
has magnified the effects of lower fertility and greater longevity is the
babyboom that arrived in most rich countries after the Second World War.
{{U}} {{U}} 14 {{/U}} {{/U}}{{U}}The tinting varied slightly from
place to place, but in America-where the effect was strongest-it covered roughly
the 20 years from 1945, a period when nearly 80 million Americans were born{{/U}}.
The first of them are now coming up to retirement. For the next 20 years those
baby-boomers will be swelling the ranks of pensioners, which will lead to a
rapid drop in the working population all over the rich world.
As always, the averages mask considerable diversity. {{U}} {{U}}
15 {{/U}} {{/U}}{{U}}Most developing countries do not have to worry about
ageing-yet, in the longer term, however, the same factors as in the rich
world-fewer births, longer lives-will cause poorer countries to age
too.{{/U}}