Paradox: What Is Ending The Population Explosion?

Select Countries Births per woman.

Surprisingly, humanity is at ‘peak child‘ and looks to be heading to population stability. We are still are left with the aftermath and an overpopulated planet, but of the population explosion, is ending. Human ‘births’ per woman has fallen from 5.0 in around 1960, to around 2.3 in 2021. There are countless studies of population trends, but in the end, most explanations for the fall in population contain contradictions. Three main types of explanations for the decline in birth rates coming just when it was needed are explored here.

  • Background
  • Explanations categories:
    1. Luck: A Lucky Coincidence
      • 1a. The birth rate happened to fall when we need it to
      • 1b. Population Coincidence Paradox: Still Luck?
    2. Planned Responses to solve overpopulation.
    3. Nature, an instinctive reduction of birth-rates.
  • Conclusion: The Paradox.


The explosions starts as an unfortunate side-effect of improved medicine.

Humanity has just experienced a population explosion. While there are various factors that enabled the explosion to continue, there is one single clear reason why the explosion happened. It is not birth rates, which actually fell as the population explosion happened. There is clear data that birth rates feel, and at no time during the explosion reached pre-explosion birth-rates, even during ‘baby-booms’.

The difference between the time of population explosion and the time before, is that previously over half of all children died before growing up to have their own families. Once we solved the huge historic problem of half of all children dying before becoming adults, almost all children then went on to have their own families.

There are people who explore theories such as how improved farming allowed supporting an increased population, and factors such of these explain how managed to sustain the increased population, but it not the cause of the increased population. Given that birth rates did not increase, it is clear that is the advances in medicine that caused the explosion.

Humans reduced infant mortality to end the tragic loss of life, and the population explosion was an unfortunate side effect.

not because we wanted a population explosion, the goal was . The population explosion was an unfortunate, accidental side effect of saving children’s lives. It is an ‘accident’ in the sense that we did not pre-plan the population explosion, it was just a side effect that, without something bring the resulting growth rate to an end, could have ended civilization.

The explosion ends due to decreased ‘births-per-woman’, another side effect?

At peak 20th century growth rates of 2.1%, or 42 times that 12,000 year average, the same increase in population as occurred over 12,000 years, would take place in just 200 years. This is not sustainable, but now births per woman has startlingly fell to way below what was seen during those 12,000 years, potentially bringing population growth back a similar level to the historic normal.

Again, we now what ended the boom, or a least is far at least still finalising bringing the boom to an end. Birth rates ended the . The rate fell growth that would doubling the world population every 35 years, to a rate consistent with a stable population.

Between 1960 and 2020, births per woman fell from over 5.0 to around 2.3. This leaves the question, why did the births per woman then fall? Was it like increased population growth rate, just an accident, or an accidental side effect of another change in society. just as with the increased population growth?

Just in Time?

How many times in movies is the bomb diffused with just moments to spare before there would have been a disaster?

The ending of the population explosion in some ways seems just like those movies. In the 1970s, when the fall in birth rates started, many people were already predicting disaster unless something was done. In

If, instead of this fall in birth-rates taking place, population growth birth rates more typical of human history had continued, there would be 18 billion people today (2021), in place of the less than 8 billion people we actually have. If population had grown to 18 billion, what would the world now be like? Imagine CO2 levels having been rising at over 2x the current rate, deforestation accelerated to access resources for over twice the number of people, and all those mouths to feed.

Despite birth-rates already starting to fall, in the 1970s when we reached a population of 4 billion, growth was 2.1% per annum and accelerating. Just maintaining those rates would already have almost doubled the number of people added to the population since the 1970s. Generally, it seems most likely the disaster predicted by many as early as in the 1960s, would have come already come true without the fall in birth rates. Instead, through the falling births per woman, we just may have averted disaster.

How did the fall happen just in time?

1. Luck

1a. Luck: We Are The Lucky Ones.

Perhaps it was pure luck the birth-rates happened to start falling when we desperately needed them to fall?

If there is only one planet in this galaxy of over 100 billion stars with an advanced intelligent life form, what are the odds of being born on that planet? Incredibly low, but since only and advanced intelligent life form would contemplate those odds, the only people thinking about the odds, have already won that very lottery. In other words, unlikely as any event may be, if the event is required for our survival, that event must have happened, because we are here to think about it. So anything required for us to be alive, no matter how unlikely, happened in our past, because in order to think about what happened, we have to be on a planet where it did happen.

The same principle could be applied to the fall in birth rate. Perhaps it just happened randomly, despite it being incredibly unlikely. The only reason we are still able to contemplate those odds, is that it did happen, which enabled us to still live in a civilized society. All the people on planets were the birth rate did not fall, at a similar point in their society on their planet, died from overpopulation, and this is just another reason why we are not seeing other advanced civilizations.

Summary: It is possible that the reduction in birth rates just happened almost randomly, and just as there is no point in a lottery winner wondering ‘why me’, there is no point in wondering about birth rates, it is just chance.

1b. Mostly Luck, but we know why were lucky.

People have looked at the falling birth rate, and in retrospect formed explanations as to why the number of children per woman has decreased.

What explains the change in the number of children women have?

Empowerment of women
Women’s labor force participation
Increasing well being and status of children
Increasing prosperity and structural transformation of the economy
Culture and norms
Family planning (Untargeted)
Religion and fertility
Family planning (Targeting having less children as in Bangladesh)
Coercive policy interventions
Fertility is first falling with development – and then rising with development


This is not my list, but the list from ‘our world in data’. I would change ’empowerment of women’ to ‘education and empowerment of women’, although when I follow the link, it does become clear they do associate ’empowerment’ and ‘education’.

These ‘explanations’, can be divided into three categories:

  1. Actions specifically designed to reduce birth-rates.
  2. Changes/actions which logically reduce birth-rates, but target other outcomes and reduction of birth rates is a side effect.
  3. Changes/actions targeting other outcomes, which may or may not also change/reduce birth-rates.

Category one includes only coercive policy interventions , and a specific type of family planning that also targets population growth, as practiced in Bangladesh.

All the rest of the explanations are about actions taken for another reason. These are not specific steps taken to limit population growth, in the same way that reducing child mortality was not designed to create population growth. In all these cases, the impact on population growth is a side effect.

Birth-rates having been reduced by side-effects, puts the reduction of birth-rates into the same category as the reducing child mortality triggering population growth: a predicable but unplanned accident.

The implication is that if we had a society where, religion or some other factor delayed the globalisation of education of women for years, or we had not invented the pill at the time we did, our society we would probably have collapsed due to overpopulation.

If, as is generally proposed, these changes/actions which have been responsible for reducing birth-rates, predominantly did not have reducing birth-rates as a primary goal, then at least most of the reduction of birth-rates in time to prevent a catastrophe, can be considered an unfortunate accident.

Summary: So, still luck, as above, but analysing in more detail, exactly what were the things that luckily happened at just the right time to result in our lucky outcome.

2. Planned Responses to solve overpopulation.

Two of the explanations listed above did, did not just luckily result in lowering birth-rates, but were specifically designed to reduce birth rates.

Family planning (Targeting less children as in Bangladesh)
Coercive policy interventions

There is a full spectrum possible between trying to educate people on the advantages of less children, through to the one child policy of China which went as far as mandatory contraception and sterilization in some cases for women who already had two children. In between education and the more drastic measures are financial and employment based incentives and limitations.

Certainly there were place in the world that took steps some time after 1960 in order to reduce birth rates.

  • China introduced the one child policy in 1979 after around 10 years of an earlier two child policy.
  • Various countries introduced public campaigns to encourage parents to only have 2 children, including:
    • Vietnam (1960s), Hong Kong (1970), Singapore(1980).
  • Some countries including India (2019), have introduced incentives for less children, and others (UK, 2012) have contemplated such measures,
  • Other countries have had ‘family planning’ programs, and education programs encouraging parents to have less children.
    • see Bangladesh example in Hans Rosing video here.


The one child policy was introduced in China in 1979, when world population growth rate was still close to the 1972 peak, but there is another story, which requires considering the population pyramid for China in 1978. Looking at the pyramid, at first it looks like two child policy introduced 10 years earlier , partly in response to the great famine, was starting to work, The 0-4 year population was for the 1st time in a long time, smaller now than it was 5 years ago (the now 5-9 band). But, now consider that each five year band represents the children born to the population four bars, or around 20 years earlier. The children in the 0-4 band, were mostly born to the 20-24 band, and therefore, still represented an increase relative to their parents, and as each of the next two groups to become 20-24 in 5, and then 10 years, were even larger populations, on trend, the population would again be growing. They felt they needed more!

Hence the move to a ‘one child’ policy. The pyramid of 20 years later shows there was logic to moving to the even stricter ‘on child’ policy and even despite this, and the peak years (5-9, 10-14) were again peak years 20 years later, but the pyramid is no longer so “bottom heavy”. The world population in 1978 was 4.3 billion and increased 40% to almost 6 billion by 1998. The 31% increase in China from 0.97 in 1978 billion to 1.27 billion is below that world average. At world average, China would have reached. So how many less people than the world trend in China after ten years of 2 child policy followed by 20 years of 1 child policy?

world_increase_rate x china_in_78 - china_in_98 = (6/4.3)x.97-1.27 = 0.083 billion

Today, as the population pyramid of China has been transformed from that of 1978. The people over 50, were all born before ‘child policies’, and the top of the pyramid is still the traditional shape of from the 1960s and earlier. But from age 50 down, the shape is no longer a pyramid, but the straight sided shape of a stable population, and almost half, 48%, of the population are over 40.

Overall, from 1978 until now, the population of China grew by 48% from 0.97 billion to 1.44 billion, while the world population grew 81% from 4.3 billion to 7.79 billion. If China had increased population at the rate of the rest of the world, China would have 317 million extra people. Considering growth in China was over world average before the two child policy, perhaps China could kept growing beyond the world average? It is hard to project exactly what would have happened had China not introduced the policy. Would an extra 317 million people, or more, been able to survive? If such a population had been able to survive, would would the environment of China look like as a result, and how would having so many people have damaged the economy?

Just looking at averages, the fall in birth-rates since 1972 globally have spared the world needing to support at least 3.2 billion more people. The efforts by China have outperformed the rest of the world, and that contribution by China meant that the rest of the world had to find around 10% less reduction. Without China, there could be 317 million extra people on Earth today.

The result is significant, but only explains around 10% of the world reduction in population growth. Perhaps the policy of Bangladesh and other countries can account for another 5% of the impact, but that still leaves over 85% of the reduction in birth rates down to measures not targeted at reducing birth rates. Why effective the entire rest of the world also reduced birth-rates is down to conjecture, but what is clear is there was no world-wide deliberate program as in China.

It is not even in the same category as the way the population explosion started, where although the goal of eliminating child mortality clear was not targeted at increasing population growth, it is certain that more people alive must be a consequence. Measures such as ’empowerment of women’ do may logically be a reason for less children, but does not with certainly preclude women having the same number of children. As a cause of decrease in birth-rates, it is feasible, but untestable explanation.

The biggest conundrum with all explanations that did not deliberately seek to address birth-rates, is just how co-incidental it is that these events not only produced the lucky result of reducing birth-rates, but took place and had the effect just when we needed birth-rates to be reduced.

Worldwide, the birth-rate (Niger and some other countries in Africa excepted) birth-rates fell dramatically without intervention like China. Why? Is this just luck? Or something more?

3. Nature: an instinctive reduction of birth-rates.

The one possible factor not explored in material I have found so far, is what if humans naturally reduce birth-rates when they need to? The need to have children is hard-wired into humanity, just as reproduction is hard-wired into all living things. Might that hard-wiring be more sophisticated than we give credit?

Consider our nearest relatives, chimpanzees and gorillas. They seem to have stable populations, without accidentally having population explosions immediately conditions are more favourable. Just perhaps, our basic instinct to have children, is also to have children in balance.

People in the past never lived in ecological balance with nature, they died in ecological balance with nature. It was utterly tragic!

Hans Rosling (see video, 19m

The point by Hans is that the birth rate only produced a balance once deaths were also considered. But it was in balance. Historically, humans produced the right amount of children such that, overall there was balance. Now consider, what if the system takes time to adjust, but in fact humans have now simply adjusted to this new lower death-rate, by naturally having a lower-birth rate?

What if, the measures introduced in China were only required while people adjusted, and are no longer necessary? What if the explosion occurred because the change in infant mortality was so sudden that we were too slow to adapt?

To me this seems possible. However, in the jungle, the instinct to reproduce could pick up signals to trigger people to having more or less children in order to maintain the balance, but how could that work in modern society?

The attraction of this hypothesis, is that instead of needing to accept that birth rates fell because changes to society that triggered lower birth rates just happened to occur at the right time, the premise becomes that it is natural to have less children once there are seen to survive.

There is a lot to explore before declaring everything adds up. How the signals could work in society? Wouldn’t it be logical if people are responding to environment for people in crowded areas to have less children? So many questions that a dedicated exploration make sense.

But, just perhaps, that is NOT coincidence.

Conclusion: The Paradox.

Programs to reduce birth-rates played a role in ending the population explosion, but on all evidence contributed not more than around 15% of the reduction globally. The paradox for current explanations for the other 85% of the reduction, is that none explain the birth-rate reduction alone, requiring a co-incidence of several factors that just happen have a side-effect of reducing birth-rates, all occurring right at the time when humanity requires birth-rates to fall.

It would seem far more logical that some underlying drive for lower birth-rates was able to be accelerated by working with some of these factors, than they all happened to cause the desired result at the right time.

Either a co-incidence, or an underlying factor yet to be further explored.

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