Population pyramids: Powerful predictors of the future - Kim Preshoff

Transcriber: Jessica Ruby Reviewer: Caroline Cristal

翻译人员: Corrine Yan 校对人员: Jenny Yang

俄罗斯是世界上版图面积最大的国家，

Russia, with the largest territory in the world,

has roughly the same total population as Nigeria,

拥有着几乎与尼日利亚相同的人口数量，

a country 1/16 its size.

而尼日利亚的国土面积仅是俄罗斯的1/16。

But this similarity won't last long.

但在不久的的将来两国人口数量将产生一定的差距

One of the populations is rapidly growing,

其中一个国家的人口数量正在急剧增加，

while the other is slowly declining.

而另一个国家的人口数量在缓慢减少。

What can this tell us about the two countries?

我们能够从中得到关于这两个国家的哪些信息呢？

Population statistics are some of the most important data

人口统计数据是众多的社会科学家以及 政策专家必须研究的重要数据之一。

social scientists and policy experts have to work with.

But understanding a country's situation

然而，要了解一个国家的国情，

and making accurate predictions

并做出准确的预测

requires knowing not just the total size of the population

不仅需要知道其人口总数

but its internal characteristics,

更要知道数据中所隐含的的一些内在特点，

such as age and gender distribution.

比如年龄和性别分布。

So, how can we keep track of all that data

因此，我们如何用一种通俗易懂的 方式来解读所有相关数据呢？

in a way that makes it easy to comprehend?

Complex data is more easily interpreted

将复杂的数据可视化会使其更加简单易懂，

through visualization,

and one of the ways that demographers represent

通常人口学家会用

the internal distribution of a population

人口金字塔的方式来展现人口分布。

is the population pyramid.

Here, the data is divided by gender

在“人口金字塔”中，人口数据会按性别划分开，

with females on one side and males on the other.

男女各占一边。

The population numbers are shown

所显示的人口数量

for each five-year age interval,

以五岁为一个年龄层，

starting from 0-4

始于0-4

and continuing up to 100 and up.

继续至100及以上。

These intervals are grouped together

这些年龄层被分成了：

into pre-reproductive (0-14),

预生殖期（0-14），生殖期（15-44） 以及后生殖期（45及以上）。

reproductive (15-44),

and post-reproductive years (45 and up).

Such a population pyramid can be a powerful predictor

这种人口金字塔可以成为 预测未来人口发展趋势的有力工具。

of future population trends.

For example,

比方说，

Rwanda's population pyramid shows it to be a fast-growing country,

卢旺达的人口金字塔显示 卢旺达是一个人口快速增长的国家。

with most of the population

该国的大多数人口

being in the youngest age groups at the bottom of the pyramid.

为金字塔底端的最年轻的群体。

The number will grow rapidly in the coming years.

在未来的几年里，该国的人口数量将会快速增长。

As today's children reach their reproductive years

随着如今的孩子达到生殖年龄

and have children of their own,

并且有了他们自己的孩子，

the total population is almost certain to double

总人口数量很有可能

within the next few decades.

在将来的几十年里翻一翻。

For our second example,

再举一个例子，

let's look at Canada,

让我们来看看加拿大，

where most of the population is clustered

该国的大多数人口聚集在

around the middle of the graph.

图表的中间部分。

Because there are less people

因为处在预生殖期阶段的人口数量 少于在生殖期阶段的人口数量，

in the pre-reproductive age groups

than there are in the reproductive ones,

the population will grow more slowly,

因此随着未来达到生殖期的人口数量的减少，

该国的人口总数在未来将会增长的比较缓慢。

as the number of people reaching their reproductive years decreases.

Finally, let's look at Japan.

最后，我们来看看日本。

Because the majority of its population

由于其大部分人口都处在后生殖期阶段，

is in its post-reproductive years

and the number of people is smaller

而年龄越小的阶段的人口越少，

at each younger interval,

this means that at current rates of reproduction

这就意味着，按目前的生殖率计算，

the population will begin to decline

将来的人口总量将会下降，

as fewer and fewer people reach reproductive age.

因为达到生殖年龄的人口将越来越少。

Comparing these three population pyramids

依次比较三种人口金字塔模型，

side by side

shows us three different stages

表现出了一个国家从前工业化阶段 进入到工业化或后工业化时期

in a demographic transition,

as a country moves from a pre-industrial society

to one with an industrial

人口数量变化将要经历的三种不同阶段。

or post-industrial economy.

Countries that have only recently begun

刚开始工业化进程的国家

the process of industrialization

通常会伴随着人口平均寿命的增长和儿童死亡率的下降

typically see an increase in life expectancy

and a fall in child mortality rates

as a result of improvements

这是由于在医药、卫生和食物供给方面的改善。

in medicine, sanitation, and food supply.

While birth rates remain constant,

当出生率的达到稳定时，

leading to a population boom.

人口数量将迎来爆炸性增长。

Developing countries that are farther along

那些工业化更加发达的的发展中国家将出现生育率下降，

in the industrialization process

begin to see a fall in birth rates,

due to factors such as

原因在于其妇女在除了抚养孩子以外， 受教育的程度和就业机会得到改善，

increased education and opportunities for women outside of child-rearing

and a move from rural to urban living

以及从农村到城市的生活变迁 使得孩子多的大家庭的生活经济成本增加。

that makes having large families

less economically advantageous.

Finally, countries in advanced stages of industrialization

最后，那些处在工业化鼎盛时期的国家，

reach a point

其出生率和死亡率都比较小，

where both birth and death rates are low,

and the population remains stable

人口数量较稳定，甚至开始下降。

or even begins to decline.

Now, let's take a look at the projected population pyramids

现在，让我们来预测以上三个国家 在2050年的人口金字塔模型。

for the same three countries in 2050.

What do these tell us

这些能够告诉我们每个国家 将来人口数量变化的什么信息呢？

about the expected changes

in each country's population,

and what kinds of factors

以及哪些因素能够改变这些预测模型的形状？

can alter the shape of these future pyramids?

A population pyramid can be useful

人口金字塔模型不仅可以用来预测一个国家的未来，

not only as a predictor of a country's future

but as a record of its past.

同时也反映着她的历史。

Russia's population pyramid

从俄罗斯的人口金字塔中，

still bears the scars of World War II,

我们仍然能够看到第二次世界大战的伤痕。

which explains both the fewer numbers of elderly men

一方面因为老人中男性的数量少于女性，

compared to elderly women

另一方面可以看到男性的数量在之后突然猛增，

and the relatively sudden population increase

as soldiers returned from the war

这是因为士兵从战场上回来，回复到正常生活中。

and normal life resumed.

China's population pyramid

中国的人口金字塔

reflects the establishment of the one child policy

反映了其计划生育政策实行了35年的效果。

35 years before,

which prevented a population boom

该政策避免了像卢旺达那样的人口爆发，

such as that of Rwanda

but also led to sex-selective abortions,

但也导致了因人为选择性别而引发的堕胎，

resulting in more male children than female children.

其结果是男孩的数量多于女孩。

Finally, the pyramid for the United States

最后，美国的人口金字塔

shows the baby boom that followed World War II.

反映了第二次世界大战之后的生育高峰。

As you can see,

由此可见，人口金字塔能告诉 我们的信息远不止一套数字。

population pyramids tell us far more

about a country

than just a set of numbers,

by showing both where it's been

仅仅通过一个图表，它能够 告诉我们一个国家的过去和未来。

and where it's headed

within a single image.

And in today's increasingly interconnected world,

在如今越来越紧密联系的世界中，

facing issues such as food shortages,

面对像食物短缺、生态系统威胁 和经济不平等诸多问题，

ecological threats, and economic disparities,

it is increasingly important

越来越重要的一点是，

for both scientists and policy makers

科学家和决策者们能够认真和密切地 认识到人口数量及其影响因素。

to have a rich and complex understanding

of populations and the factors affecting them.