Our numbers have skyrocketed, from 1 billion in 1800, to 2.3 billion in 1940, 3.7 billion in 1970, and 7.4 billion in 2016.

全球人口數從 1800 年的 10 億人、1940 年的 23 億、1970 年的 37 億，一路飆升到現在的 74 億人。

The world population increased fourfold in the last century, so what can we expect for the next century?

世界人口在僅上世紀就攀升了四倍，那下個世紀又會如何增長呢？

And what does population growth mean for our future?

人口增長對於我們的未來有什麼影響？

Will there be mass-migration?

會有大規模遷移的現象嗎？

Overcrowded slums and megacities covering continents?

爆滿的貧民窟及大城市充滿整個大陸？

Diseases and pollution?

會有疾病或汙染嗎？

Chaos and violence over energy, water, and food?

或是因為能源、水、食物所造成混亂、暴動頻傳？

And the human species focused only on sustaining itself?

而人類只在意自己的生存與否？

Will population growth destroy our way of life?

人口增長會不會因此摧毀了我們的生活方式呢？

Or is this prophecy just ungrounded panic?

或只是會造成不必要的恐慌預言？

In the 1960's population growth reached an unprecedented rate, which leads to apocalyptic prophecies.

在 1960 年人口的增長以前所未見的速度成長，甚至引起了世界末日的預言。

The poor would procreate endlessly and overrun the developed world.

窮人會成為主宰世界的勢力，並超越那些已開發國家。

The legend of overpopulation was born.

這也是人口過剩的原因。

But it turns out high birth rates and the population explosion are not permanent features of some cultures or countries, but rather a part of a four step process the whole world is going through, the demographic transition.

但是事實證明高出生率及人口爆炸並不僅僅是特定國家的永遠專利，而是世界上所有國家都會經歷的四個階段之一，也就是所謂的人口轉型理論。

Most developed countries have already made the transition, while other countries are doing it right now.

大部分的已開發國家都已經成功轉型，其他國家則是正在經歷這個過程。

Let's go back to the 18th century, when the entire world, including Europe, was in the first stage of the demographic transition.

讓我們回到 18 世紀看看，當時全世界，包括歐洲，都正面臨人口轉型的第一階段。

By today's standards, Europe was worse off than a developing region, suffering from poor sanitation, poor diets, and poor medicine.

用現今的標準來看的話，當時的衛生、飲食條件差，且醫療不普及，所以歐洲狀況很糟。

A lot of people were born, but lots of them died just as fast, so the population hardly grew.

出生率很多，但很多新生兒很多就死亡了，所以人口幾乎沒增長。

Women had between 4 and 6 children, but only 2 of them would reach adulthood.

婦女平均生 4 到 6 個小孩，但是只有 2 個能夠長大成人。

Then the industrial revolution happened in the UK and bought the greatest change in human living conditions since the agricultural revolution.

之後，在英國發生的工業革命帶給英國自農業革命以來最大的轉變。

People went from being peasants to workers.

人們從農夫變成工人。

Manufactured goods were mass produced and became widely available.

隨處可見，各種商品以大量生產的方式製造出來。

The sciences flourished and advanced transportation, communication, and medicine.

科學革新，帶來交通運輸、通訊科技、醫療技術的革新。

The role of women in society shifted and created the conditions for their emancipation.

社會中的女性角色轉變，讓女性得以解放。

Slowly this economic progress not only formed a middle class, but also raised standards of living and health care for the poor working population.

慢慢地這種經濟成長不只讓中產階級出現，同時也為勞工階級帶來生存權的保障。

The second transition stage started.

人口轉型的第二階段開始。

Better food supplies, hygiene and medicine, meant people stopped dying all the time, especially so, at a very young age.

糧食供應更加充足、衛生與醫療的進步，都使得人類死亡率下降，特別是年輕人口。

The result was a population explosion.

結果就是人口爆炸。

Doubling the UK's population between 1750 and 1850.

英國在 1750 年到 1850 年間人口成長倍增。

The main reasons families used to have lots of children was that only a few of them were likely to survive.

當初當家庭會有那麼多小孩，是因為只有少數能存活下來。

Now that had changed, so the third stage of transition was set in motion.

然而今非昔比，也就進到人口轉型的第三階段。

Fewer babies were conceived, and population growth slowed down.

出生率降低，而人口成長趨緩。

Eventually a balance emerged, fewer people were dying and fewer children were born, so the death rate and birth rate became stable.

最後就趨近於平衡，更少人死亡、更少孩童出生，所以出生率、死亡率變得穩定。

Britain had reached the fourth stage of the demographic transition.

英國已經達到人口轉型的第四階段。

This didn't only happen in the UK, more and more countries went through the four stages.

但其實不僅僅是在英國，越來越多的國家也進展到人口轉型的第四階段。

First, many births and many deaths due to bad living conditions.

首先，由於生活條件不佳，導致高出生率、高死亡率。

Second, better living conditions leading to fewer deaths and a population explosion.

第二，生活條件改善，死亡人數下降，人口數激增。

Third, fewer deaths resulting in fewer births, and population growth came to an end.

第三，低死亡率造成出生率也下降，而人口數則不再增長。

But if birth rates have dropped so much, why is the population still growing so fast?

但是如果出生率已經大幅的下降，為什麼人口還是快速增長呢？

Well, the children born in the population explosion of the 70's and 80's are having kids themselves now, leading to a noticeable spike in overall population.

那是因為在 1970 至 1980 年代人口爆炸時期出生的孩子，現在都也生了自己的孩子，導致總人口數明顯的增長。

But they are having far fewer children on average than their parents.

但是，他們已經比他們的父母生得要少。

The average today is 2.5, it was 5, 40 years ago.

相較於 40 年前平均值是 5，現在則只剩 2.5。

So as this generation gets older, and fertility declines further, the rate of population growth will keep on slowing.

所以當這一代的人變老，而生育率也隨之下降，人口增長的速度就漸漸趨緩。

This is true for every country.

每個國家都會遇到這個狀況。

In the west, we tend to overlook progress in other regions of the world.

在西方國家，我們往往忽略了世界上其他地區的發展。

But actually most of the world's countries have made it to the fourth stage.

但其實世界上大部分的國家都已經到達第四階段。

Just look at Bangladesh. In 1971, the average woman had 7 kids, but 25% of them would die before the age of 5.

以孟加拉為例，在 1971 年平均每個婦女都會有 7 個小孩，但是有四分之一的小孩活不過 5 歲。

In 2015, the mortality rate was down to 3.8% and women had only 2.2 kids on average.

2015 年時，死亡率則降到只剩 3.8%，婦女平均孩童也只剩 2.2 位。

This is the rule, not an exception, we're not special, we just had a head start.

這是必然的，並不是特例，我們並沒有比較特別，我們只是出發得比較早。

It took developed countries about 80 years to reduce fertility from more than 6 children, to less than 3.

已開發國家花了大約 80 年的時間才將生育率從 6 位小孩降低到不到 3 位。

Others are catching up fast. Malaysia and South Africa did it in only 34 years; Bangladesh took just 20.

而其他國家正迎頭趕上。馬來西亞和南非只花了 34 年，而孟加拉更是只花了 20 年。

Iran managed it in 10 years.

伊朗則是在 10 年內就辦到了。

All these countries that are catching up didn't have to start from scratch and the more support they get, the faster they catch up.

那些正在趕上的國家並不是從零開始，它們有許多的幫助，使得他們能夠迎頭趕上。

This is why programs that help lower child mortality or help poor nations develop, are so important.

這就是為什麼，幫助降低死亡率或幫助貧窮國家開發是很重要的。

No matter what your motivation is, whether you dream of a world where all people live in freedom and wealth, or you just want fewer refugees coming into your country, the simple truth is, that it's beneficial to you personally if people on the other side of the globe can live a good life.

不管你的動機是什麼，不管你是不是夢想全世界人都能活得更自由、更富裕，或只是希望減少進入你們國家的難民，簡單而言就是，如果地球另一端的人擁有美好的生活，對你也有好處。

And we are getting there, the percentage of people living in extreme poverty has never been as low as today.

而且就快到達了，現在生活在赤貧中的人口已經越來越少。

So the future of global population growth is actually not an apocalyptic prophecy at all, it's a promise!

所以人口成長所帶來的未來不是世界末日的預言，而是承諾。

Population growth will come to an end.

人口增長即將邁入句點。

The UN forecasts that the 12th billionth human will never be born at all.

根據聯合國預測，地球人口不會超過 120 億人。

And as the development level of the world rises, the number of people with a higher education will increase tenfold.

隨著世界發展水平的提升，受過高等教育的人數將會是原本的 10 倍。

Countries who used to be in need, will help advance development instead.

曾經是需要幫助的國家，也能夠幫助世界的發展。

More people is going to mean more people able to advance our species.

更多的人口，代表能夠幫助人類進步的的人變得更多。

This video was a collaboration with Max Roser and ourworldindata, where he explores the progress of humanity through research and data visualisation.

此影片是由 Max Roser 和 ourworldindata 共同製作，透過研究及數據分析人類的進步。

Make sure to check it out!

一定要來看看唷！

In 2016 we were able to make more and better content than ever before, because of your support on Patreon.com.

感謝你們在Patreon.com的支持，所以我們2016年能夠比之前做出更好的內容

Thank you so much and we will be back in the year 12,017.

感謝觀賞，我們12017年再見