Can anything be done to support global development? Should we not do it to avoid overpopulation?

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Max Roser (2017) - "Can anything be done to support global development? Should we not do it to avoid overpopulation?". Published online at Retrieved from: '' [Online Resource]

Places matter

Where you live matters for the living conditions you are enjoying:

  • In the countries with the poorest health in the world today – in the center of Africa – more than one out of ten children born today will die before it is five years old. In the healthiest countries of the world – in Europe and East Asia – only 1 in 250 children will die before it is 5 years old. A child in Angola is 70-times more likely to die in Angola than in Iceland. – Here is the map.
  • In the countries where people have the best education – in Europe and North America –, people have on average 12 years or more of formal education. In countries with the poorest education, the population has on average fewer than two years of education. – Here is the data.
  • And if you look at material wellbeing and you compare the richest countries of the world – among them Norway with a GDP per capita of 63,811 international-$ – to the poorest country in the world – the Central African Republic with 648 international-$ – then you find a 98-fold difference. Norwegians can spend in 1 month what people in the Central African Republic can spend in 8 years and two months (98 months). – Here is the map.1

No matter what you do (except for leaving the country), when you are born in a poor place you will not be able to get the odds of your baby dying down to the average level in a healthy country and it is immensely harder for you to obtain the level of education an average person gets in the best-off places. And for income the economist Branko Milanovic has estimated just how much the place you live in matters: Dominating all differences in skills between people and the different effort they put into their jobs, Milanovic found that simply the place where people live explains two-thirds of the variation of peoples incomes around the world.2

Your living conditions are much more determined by the place that you are born into than by the choices in life you have made.

Places change

People's living conditions change when places change. And fortunately places change very much. In those places that have the best health today every third child died. And similarly, even basic education was not available for most in those countries that enjoy the best education today, and in today's rich countries the majority of people lived in extreme poverty a few generations ago.

The good news is that these changes happen in today's poorest countries too. Let's look at three of these changes in the three aspects mentioned above:

The first visualization shows that as most countries around the world are achieving economic growth the share of people in extreme poverty is falling. (You find more about extreme poverty and also the link to economic growth in our entry.)

This second visualization shows that fewer children are denied an education. Over a period when the poorest world regions had to provide for an increasing number of school-age-children, the number of children who are out-of-school was almost halved.

And the third visualization shows the progress against malaria. Over just 15 years the number of malaria deaths has almost halved, from 840,000 deaths per year to 440,000.

It is particularly important to make progress against malaria, as it is one of the leading causes of child mortality – 72% of the disease's victims are children younger than 5 years old and globally every tenth child that died in 2016, died because of malaria.3

How was this progress possible? In a recent publication in Nature, the researchers Bhatt et al. (2015)4 studied the decline of cases of malaria in Africa between 2000 and 2015. From looking at the chart we see that this is where most of the reduction happened. The researchers found that the single most important contributor to the decline was the increased distribution of insecticide-treated bed nets. Bed nets alone were responsible for the aversion of 68% of the 663 million averted cases in Africa between 2000 and 2015. These are 451 million averted cases of malaria.5

Large financial efforts were required for this achievement. The WHO Malaria Report 20166 writes: "Progress in reducing malaria incidence and mortality between 2000 and 2015 was made possible by large increases in the financing of malaria control and elimination programmes." In 2015, US$ 2.9 billion7 were available globally in the fight against malaria. And here the richer parts of the world were able to help people in the poorer parts: One third of the funding for malaria control and elimination today comes currently from countries in which malaria is endemic and the remaining two-thirds is paid for by richer countries, especially the US and the UK.8

This is a truly important achievement in global health, yet the evidence shows that much more is possible and with continued effort and funding it will be possible to make more progress against malaria. Because the fight against malaria is achievable yet still still underfunded it is one of the causes that is recommended by charity evaluators like Givewell or Giving What We Can for everyone who wants to support a particular important and cost-effective development goal. Also the authors of the Nature study warn that with regard to the distribution of malaria bed nets we are "still below target levels".

Is it a good thing that places change?

Above I made two points:

  • Living conditions around the world – in terms of health, education, and poverty – are extremely unequal and whether you are healthy, educated, and rich is to a large degree determined by where and when you are born – very likely you would not be healthy, educated, and rich if you were born in your hometown two centuries ago and you would not be healthy, educated, and rich if you are born in Madagascar.
  • And second, places are changing and there are ways in which the richer population of the world can support the less rich parts of the world.

When I suggest the second point, most people I talk to have one of two reactions: either they agree or they doubt that it is possible to do anything – the reduction of malaria deaths should answer to this second reaction.9

But there is a third group of people that react very different entirely. It is a small, but a very vocal group.

Quote by Philipp that motivates this: "Foreign aid strategies seem to focus on healing diseases and preventing children from dying, which feels really weird and counter intuitive. So to stop overpopulation should we stop our efforts there? After all, if we stop people from dying they will only have more children, making the problem worse, leading to more poverty and streams of refugees. This is one of the most regular comments we get when we make videos about diseases or poverty. So we wanted to look at this in more detail."

These people would argue it is a good thing that malaria funding is "below target levels".

Those who promote this ideas and send us these comments assert that dead children are not a bad thing, but in fact, since their deaths prevent 'overpopulation', it is certainly sad but ultimately good that they die. Those who make this argument present this as one of the hard and harsh truths that should be obvious for every one who has common sense, but because of the "political correctness" that forbids us to say what is true, none of the "experts" dares to say it. So they feel that it is up to them to explain this to the world and it is only thanks to their heroic bravery and clear-sightedness that they dare to stand up for the "politically incorrect" truth about the do-gooder idiocy of saving children's lives.

Is that true? Should we be concerned that preventing deaths leads to overpopulation and more poverty? Should we therefore stop helping people?

Let's look at the evidence.

A first way to see whether dying children are keeping population growth in check is to see whether populations grow indeed more slowly where many children die. The visualization below plots the two relevant variables against each other. What we see is the exact opposite of what you would expect if you think that child mortality is a way to limit population growth: Populations are growing most rapidly in those places where most children are dying.

That does not explain yet what is going on, but it should make you start questioning whether your seemingly intuitive idea is actually right.

Stagnating population size in the past: High mortality kept high fertility in check

To understand what is happening today it helps to go back in time:

Population growth was very, very slow in the past: over the many generations from 10,000 BCE to the year 1700 the world population grew by only 0.04% per year. But over that same period women that lived though their reproductive years had on average between 5 and 7 children.

Knowing these two data-points is enough to know that in the past it was indeed high mortality that kept population growth in check: When women had on average around 6 children, 3 of the children were on average girls. If these three girls would live long enough to have children themselves we would have seen exponential growth of the world population. In just 10 generations one woman would have had close to 60,000 female descendants – 3, 9, 27, 81, 243, 729, 2187, 6561, 19683, 59049 – and over the 11,700 year period over which population growth was close to zero the world saw more than 400 generations. The numbers do not match up because we have to take mortality into account.

At a time when women had on average 3 girls, population growth could only be close to zero when almost every mother loses two of her three girls before they can have children themselves.10 In our long history up to around the end of the 19th century it was indeed true that mortality at a young age mattered for the rate of growth of the population. Back then, it was the very high mortality rate at a young age that kept population growth low.

Population growth today: What matters more – fertility or mortality?

To get straight to the point: While it was true that in the past mortality kept population growth in check, this is not true anymore today. As the health of the world population is vastly better than in the past, today's mortality rates are too low to matter much for population growth. To be concerned about population growth because of falling mortality rates is a reflection of being uninformed about the proportion of demographic changes in the world. If you are concerned with rapid population growth then your attention should be on fertility rather than mortality as absolutely possible changes in fertility rates have a vastly larger impact on population growth than any possible reduction of child mortality.

Mortality: How many children die?

This year 140.9 million children will be born, 386,000 children come into this world every day.

While even at the end of the 19th century around 40% of all children died before they were five years old, today the child mortality rate is 10-times lower than in the 19th century, 4.25% of all children born today will die in the next five years. This means that of the 140.9 million children born this year 134.9 million will survive and 6 million will die.11 The largest possible effect that the efforts to save children's lives can have is obviously to completely eradicate child mortality: If we would actually succeed with that and the child mortality fell to 0% tomorrow, the direct effect would be that the world population in five years would be larger by 6 million.12

Fertility: What is the magnitude of possible changes of the fertility rate?

The mortality rate is one of two drivers of population growth, the second one is what demographers refer to as the 'Total Fertility Rate' – the number of children a woman has on average.

1 – Which change of the fertility rate has an effect as large as largest possible reduction of child mortality?

To capture what is driving the number of births we have to consider two demographic variables: First the total fertility rate – the number of children a woman gives birth to over the course of her reproductive years (demographers defines this as the age bracket between 15 and 49). And second, the population of women that is actually is in that reproductive age bracket.

When many women are in the reproductive age bracket, even small changes in the fertility rate matter substantially for the size of the future population. And that is the situation the world is in today. 1.48 billion women are in the reproductive age bracket today.

Let's do some 'back of the envelope calculations': At the current fertility rate of 2.47 children per woman in her reproductive years, 1.48 billion women will have 3.6556 billion children (1.48 billion * 2.47).

To get a sense of scale we can now ask: By how much must the fertility rate change to make a difference of 6 million children – a change that is as large as the total eradication of child deaths? That is what is 'x' in: 6 million = 1.48 billion * x ? The answer is 6,000,000 / 1,480,000,000 = 0.004054054054.

This is the answer: To see a change that is as large as the total eradication of global child deaths (6 million), the global fertility rate would need to be 0.004 children per woman lower.

Is a 0.004 decline of the global fertility rate possible? Yes. The most important fact to know about the global fertility rate is that the global fertility rate decreased from 5.03 children per woman in 1965 to 2.49 children per woman today. In just fifty years the global fertility rate halved. If we set in relation to the current population of women in the reproductive age bracket, then a decline of the global fertility rate by 2.54 children per woman13 would have a 626-times larger effect on global population growth than a hypothetical total eradication of child mortality.14 That is why I am arguing that if you are concerned about population growth and you worry about a decline of child mortality you are lacking perspective.

2 – Look at which countries experience rapid population growth

A second way to see just how important fertility rates are for population growth is to ask which countries have fast population growth today. The visualization below shows the evidence. Population growth is high where the total fertility rate is high. The correlation between these two variables is as strong as you will ever see a correlation in the social sciences.

3 – The UN projects how much fertility rates matter

A third way to see just how much the fertility rate matters is to make projections about the size of the future world population: The UN's Population Division publishes projections of how the world population will grow until the end of the century. In the projection they consider the most likely – called the Medium Variant – they project that the global total fertility rate continues its decline from today's 2.47 to 1.97 children per woman at the end of the century.15  Under this scenario the world population will increase to 11.2 billion people in 2100.

In addition to the Medium Variant, the UN researchers also publish an illustrative projection of the world population that unrealistically assumes that the fertility rates in all countries are frozen at their current level. This is what this Constant Fertility scenario looks like – the world population would be 26 billion people at the end of this century. More than twice as much as under the scenario of a continuation of the decline of the global fertility rate.

Compared with possible changes of child mortality, possible changes of the global fertility rate have a much larger impact on how fast the world population is growing. The reason why child mortality does not have much importance is that compared to the large numbers that are relevant here, "too few" children die today to actually have much importance for the question of the size of the world population over the long. It is very tragic that young children die, but it is just not the case that this mortality has much importance for global population growth. And I hope by now I have convinced you that arguments to not attempt to further reduce mortality as it would lead to overpopulation are misguided. If your idea for preventing rapid population growth is to keep mortality rates high, then you are a century too late.

So let's look at the total fertility rate – how did it change and why?

Once we see that it is fertility rather than mortality that matters for population growth we can ask what matters for the fertility rate? Why did women have between 5 and 7 children in the past and fewer than 2 in many countries today?

Many factors contributed to the decline of fertility rates and we review a long series of contributing factors in our entry on the topic here.

Out of all these factors two particularly important ones stand out: The rising status and opportunities of women – and the rising status and health of children.

In the past when access to education was restricted to the best-off in society women were particularly disadvantaged. But then once societies changed and expanded access to education women got access to education and the gender inequality declined. Combined with a shift away from agriculture to jobs in which high education is required women also got increasingly equal chances in the labor market. The research shows16 that this change was particularly important for falling fertility rates. As better educated women have more opportunities outside of the household they seized these opportunities and were less keen to want a large number of children. Higher education also increased women's status in households so that their desires were increasingly respected. And studies also show that education increases the knowledge and use of contraceptives and allows better educated women to reduce the gap between the desired and the actual number of children.

In addition to the technological changes from which women benefitted, women's rights activists successfully fought for the possibility for women to work in professions from which women were previously banned without good reasons and once were allowed to become teachers or doctors the opportunities in the labor market increased even more.

To understand how women's education and the total fertility rate are related, the visualization below visualizes how these two aspects have changed over 6 decades. Each arrow in this plot shows for one country how the average number of children per woman (on the y-axis) and the years of education of women in the reproductive age (on the x-axis) have changed. It is possible to adjust the time slider below the chart and if you put start and end point to the same year you'll see a straightforward correlation.

What we see in the arrow-plot is that when women had on average fewer than 2 years of education back in the 1950s the fertility rate was between 5 and 8 children. Six decades later most women are much better educated and often have 8 or more years of education on average: As we would expect from the theory above this meant that they have much fewer children, where women have more than 8 years of education the fertility rate is less than 4 children per woman and mostly lower than 2.

You can search for particular countries with the search box in the bottom left – have a look at Iran: in 1950, when Iranian women had on average only a third of a year of schooling, they had on average 7 children. Sixty years later when Iranian women had on average 9 years of schooling they had on average 1.8 children (yes, women in Iran have today fewer children than women in the US).

In countries where women today still have only little access to education the fertility rates are still high. In Niger, the country with the highest reported fertility rate in 2010, women in the reproductive age had only 1.3 years of education on average. This is why, if you are concerned about population growth, you should be an advocate for giving women access to education.

It turns out that if you are concerned about rapid population growth you should become an advocate of women's empowerment – and you should also be particularly enthusiastic about the reduction of out-of-school children that I showed above, girls in particular benefitted from this development.

The status and health of children

The second important driver for the decline of fertility rates is the increasing status and health of children. The argument for the link between high child mortality and families' decisions for a certain number of births becomes understandable when one considers how families who want a certain number of children are forced to think in a high mortality environment. If parents have a certain target for a number of surviving children then the number of children the women gives birth to will need to be higher when the level of child mortality is higher. Families expect these tragedies and decide to have more children than they actually want. It takes however some time to adapt to falling death rates and as the health of children improves, families continue to have a high number of children. This lag between falling mortality and falling fertility is one of the key explanations for why rapid population growth is a temporary phenomenon. We review the research in detail here.

Improving child health is the second key contributor to the decline of fertility rates. And this is particularly important for our discussion here. It means that in addition to the already discussed direct effect of improved child health that contributes to a larger population, there is an indirect effect of saving children's lives that actually lowers population growth!

In the visualization below, we can see the correlation that we expect. Countries with high child mortality rates tend to have much higher fertility rates, while countries with low child mortality rates experience lower fertility rates. All countries in which the child mortality rate is higher than 9% have fertility rates higher than 4.5 children per woman.

When you press the 'play'-button in the bottom left of the chart you can see how these demographic aspects changed over time: Countries start out in the top-right corner when children die frequently and women give birth often. But as child health improves and fewer children die we see in country after country that the fertility rate falls and countries move into the bottom left corner of the chart. Consistent with the explanation above we see that women do not immediately reduce the number of birth and only after a lag of some years will the fertility rate adjust to the lower mortality rate.

And there is additional evidence, which we discuss in our entry on child mortality, that better education of mothers is having a positive impact on better health and lower mortality of the children. Better education of women reinforces the direct effect it has on fertility through an additional indirect effect via better child health. More reason yet to become a feminist and campaigner for women's rights if you care about population growth.


What we have seen is that things can really get better and people in the rich parts of the world are very lucky to be born in this place and time. Sharing some of this fortune with those that are worst off should be possible and we know that there are many ways in which it can very much make a difference.

With regard to the fear of overpopulation: The aspect that is important for population growth is not the child mortality rate. Entirely possible changes of fertility rates are vastly more important than even the most most dramatic progress in mortality rates could possibly be. Mortality rates today have very little significance for how fast the world population is growing. Those that argue otherwise have simply no sense of scale of the demographic dimensions they are talking about.

What matters for population growth is the fertility rate and we know that empowering women and indeed falling mortality will lead to a decline of fertility. Preventing child deaths is a way to reduce fertility rates.

After the fertility rate has halved over the last 50 years we are now well underway to end rapid global population growth. But the future is not certain and at what level the population will stop growing is not predetermined and will depend on how rapidly the worst-off places are making progress. Right now is a particularly crucial moment in global history as many women are entering the reproductive age – see the shape of the dark blue 2016 population pyramid below: large cohorts of women are entering the age bracket in which they can have children. Even small changes in the fertility rate will therefore make a very large difference for the size of the world population of the future.

I am less concerned about population growth and think that giving women's more opportunities and saving children's lives should be pursued for their own sake.

But if you disagree with my view on population growth and you are concerned then your goal and mine are one and the same: advocate and work for the empowerment of women around the world and do what you can to stop children from dying.

Don't try to be edgy by pretending that child deaths are a way to limit rapid population growth. They are not. Child deaths are tragedies. Many of which are entirely preventable with our modern knowledge and technology and we should therefore work to prevent them. Yes child mortality is much lower than it once was, but it is still a tragedy of extraordinary scale. 16,000 children die every day.

What we see from looking at the evidence is that just because something is 'politically incorrect', it does not mean that it is true. Quite often the truth is politically correct too.