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.

今ほど人がいたことはなかった

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

世界人口は急上昇し

And what does population growth mean for our future?

1800年 10億人

Will there be mass-migration?

1940年 23億人

Overcrowded slums and megacities covering continents?

1970年 37億人

Diseases and pollution?

そして2016年には 74億人になった

Chaos and violence over energy, water, and food?

１世紀で４倍になるなら

And the human species focused only on sustaining itself?

次の世紀はどうなるのか？

Will population growth destroy our way of life?

人口増加の行く先はどこか？

Or is this prophecy just ungrounded panic?

大規模移民

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

スラム街が大陸を覆い尽くし

The poor would procreate endlessly and overrun the developed world.

汚染が蔓延

The legend of overpopulation was born.

水や食料を奪い合うカオス

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.

人類の未来はそんな世界なのか？

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

人口増加は破滅への道か

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

それともこれはただの思い過ごしか

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

1960年 人口増加がかつてなく上昇し

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

終末予測をもたらした

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

貧困が拡大し 国家は破綻するのだと

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

人口過剰問題の誕生だ

People went from being peasants to workers.

しかし実際 高い人口増加率は

Manufactured goods were mass produced and became widely available.

永続的なものではなく

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

人口の４段階の一つにすぎなかった

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

人口転換である

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

先進国では転換は完了し

The second transition stage started.

今は他の国で進行中だ

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

ここで人口転換の最初の段階

The result was a population explosion.

18世紀のイギリスに戻ろう

Doubling the UK's population between 1750 and 1850.

当時 ヨーロッパの環境は劣悪で

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

衛生 食品 医療の問題に悩んでいた

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

出生数は多かったが早死にも多く

Fewer babies were conceived, and population growth slowed down.

人口は増えなかった

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

６人産んでも

Britain had reached the fourth stage of the demographic transition.

大人になるのは２人だった

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

しかしその後 産業革命が起き

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

農業革命により

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

人々の生活状況が一変した

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

農民は工場労働者になり

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

工業製品が大量生産されて普及した

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.

科学が進み

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

交通 通信 医薬品を発達させた

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

女性の役割が変わり

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

権利を持てるようになった

This is true for every country.

経済発展は中流階級を生み出し

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

国民全体の生活水準を向上させた

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

そして第２段階に入る

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

栄養と衛生の改善で

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

特に幼い子どもの死亡率が下がると

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

人口爆発が起きた

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

イギリスの人口は100年で倍増した

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

子どもを多く産むのは

Iran managed it in 10 years.

多くがすぐ死ぬからだった

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.

状況が変わると 出生数が減り

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

人口増加が減速する第３段階に入る

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.

バランスが生まれ

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

死亡率 出生率が低下し

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

それぞれそのままで安定した

Population growth will come to an end.

そうして転換は第４段階に到達

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

イギリスに続き

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

他の国もそのあとを追った

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

まず 劣悪な環境での多産多死

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

次に 環境の改善による人口爆発

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

そして出生数が減っていき

Make sure to check it out!

最後 人口増加は止まる

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

では出生率が低いのに

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

なぜ世界人口は急増するのか