Population is a complex area. For me to arrive at my current point of understanding, took a number of light bulb moments over the years since 2013, with each realisation shattering some of my previous beliefs, and it often taking years to be ready to take the next step. This page is a recap of my journey, and if you can move quickly from step to step, then you can absorb information faster than I can, but perhaps this information will inspire others on their own journey.
This page is about a journey towards understanding population. The steps have been:
- We are doomed: David Suzuki and The Petri Dish.
- Growth is Slowing and ‘Births per Woman’ are falling: Some Hope?
- More Hope: Hans Rosling, Peak Child, and The Population Pipeline.
- The Last 250 Years Represents An Unprecedented Population Explosion.
- What Caused the Explosion? Could It Happen Again?
- What Ended The Explosion? Solving The mystery of Falling Birth rates.
- Population Maturity: Exploring where the stability comes from.
1. We are doomed: David Suzuki and The Petri Dish.
Watching David Suzuki, it becomes clear that while economists insist that perpetual exponential growth is essential for a thriving economy, perpetual exponential growth is impossible in the natural world.
This is step 1. The evidence of huge population growth continuing is overwhelming.
It is easy to believe that greed will lead to our downfall, and perhaps it will, but it turns outs, despite continuing growth, the dire predictions of the 60s and 70s have not come true, because humans have dramatically reduced the rate of growth.
While I posted my original concern about population growth in 2014, I had already been researching and a few months of that page, I came to realise the picture is more complex than that described by David Suzuki, although understanding the principles he describes are still an important part of the journey.
Step 1 is: “population growth is out of control, we are doomed”!
2. Growth is Slowing and ‘Births per Woman’ are falling: Some Hope?
By 2015, I had learnt that exponential growth was no longer happening.
Rather than continuing the accelerating exponential growth seen up to the 1960s and 1970s, and discussed by David Suzuki, population growth was now slowing. Even and such authorities as the UN projected population growth was now on trajectory towards a peak population, and that after that, population levels could even fall.
I posted “Population: Brace, the slow down has started!” in early 2015, and there were comments from people who strongly believed “we are all having too many children and will perish as a result”, that their beliefs were not about to be altered in a short time by new information.
Too many children? If so, then of course population would still be growing. What is “too many children”? The best measure available is ‘births per woman’, also referred to as fertility rate, and rather than 2.0 being zero growth, complexity of measurement and other factors mean that around 2.3 population stability.
Clearly, births per woman has been falling, but regardless of the predictions by the UN, the data so far still has the worlds population rising.
And population growth may appear to be slowing according to the UN data, but slowing, is not necessarily stopping.
Birth rates have fallen and are still falling, the rate of growth is slowing, and this slowing growth is already is a huge change. If even the rate of population growth is slowing, then our entire economic system which has evolved to be centred on significant population growth, is in for a severe shock.
But population growth slowing is not an end to population growth, and that is where step 2 leads.
Step 2 is: Population growth is slowing, but despite declining birth rates, population growth continues and it is hard to have faith population growth will ever be sufficiently constrained.
3. More Hope: Hans Rosling, Peak Child, and The Population Pipeline.
In fact, I reached step 3, even before I discovered the talks by Hans Rosling. But to do so, I explored the topic again several time while digesting that despite the population still rising, growth was indeed set to halt. Now years later there are many more sources of this news, and by 2020 even the BBC was predicting a total population crash.
Hans explains birth rates have already fallen to the level that results in “peak child“, and that this will given time, result in the end of population growth.
This at first seems hard to believe, as you would think peak child should immediately result in “peak population“, but it turns out there is a delay due to the “population pipeline” which means that peak population is typically around half of life expectancy later than peak child.
Hans was somewhat of an optimist, with belief that although population levels are already a challenge, it is inevitable that having reached peak child population will stabilise and it will be manageable. But what about all the economists and politicians declaring we must have perpetual growth?
Step 3 is: An understanding that peak child arrives prior to peak population, and that population pipeline will mean changes to birth rates will take 30 to 50 years to fully be reflected in population growth. But there is still a nagging doubt something could result in population growth continuing.
4. The Last 200 Years Represents An Unprecedented Population Explosion.
It is natural to assume that the pattern of population growth seen by our parents, grand parents and great-grand parents has been as things have always been. But no, while ‘peak child’ and generations a similar size to that of their parents, is how things were for tens of thousands of year and all of history until the last few hundred years.
The growth from less than 1 billion people in 1801, to almost 8 billion people, a sixteen fold population increase, has happened in just close to 200 years. Homo-sapiens date back 300,000 years, and population growth from 2 homo-sapiens 300,000 years ago to 1 billion in 1801 would be an annual growth of below 0.007% and see the population double only once every 10,000 years. Not 100x faster growth of almost 7x more people in just 200 years which is 1.0% population growth every year!
Looking back at the UN data with the predictions above, it is quite clear that until around 250 years ago, population levels had been relatively stable for a long time. This rapid population growth, is specific to the last 250 years.
Why was population growth so much slower throughout history, even when people have had families with an average of well over 2 children per family. We have all heard of families of 10 or even 20 children, but of course there were also families with no children, but still the historical average has been 6 children per family.
Hans Rosling gives his answer to why there was population stablility prior to the ‘population explosion’:
Why did the worlds population grow so slowly before 1800? Throughout history, all historical records show that on average, 2 parents got more or less 6 children. But that looks, as a very fast population growth. So why didn’t it grow? Because 1.. 2.. 3.. 4.. of the the children died before growing up to be children themselves. People in the past never lived in ecological balance with nature, they died in ecological balance with nature. It was utterly tragic!Hans Rosling:,historical families sizes allow for children dying.
Step 4 is: Understanding that population growth as seen in the 19th and 20th centuries is not only unsustainable, but also unprecedented.
5. What Caused the Explosion? Could It Happen Again?
Realising we have had one explosion raises the question, how can we be sure there won’t be another population explosion, unless we know what caused this last population explosion? If we had an explosion once, perhaps the same will happen again?
It turns out, that, as explained by Hans, the explosion was caused not by larger families, but by children surviving.
But with the industrial revolution, this changed. Better wages, more food, tapped water, better sanitation, soap, medical advances…. So from all these advances, why did population grow? Was it because they got more children? No! In 1963, when I was at school [the peak of population growth], actually the number of children per woman had decreased a little in the world, to 5. And the reason for the fast population growth was the improved children survival, 4 survived at that time. But still 1 out of 5 died, that was still terrible.Hans Rosling: Children stopped dying due to improved health.
It is clear early in any analysis, that the population explosion between 1650 and 2000 represented exceptional, and from all records, unprecedented population growth. It was indeed a population explosion.
Again, what caused this period of exceptional population growth?
Increased family sizes. Increased food production.
- Reduced infant mortality.
Comparing family sizes before and during the explosion, children born per family was lower during the explosion than before the explosion. Food production may have enabled avoiding famines as a result of the population increase, but it was not more births, but slightly less births with greatly reduced infant mortality that triggered the increase. Prior to the explosion, while food was always great quality, population was not constrained by available food, and family sizes did not increase their number of children in response to more food, as clearly, families did increase the number of children being born.
Clearly the explosion was driven by the reduction in infant mortality, as explained in more detail here.
There is no question that reduced infant mortality triggered the explosion, and progressing to this step only requires reviewing the evidence and waiting for the answer to sink in.
Could It Happen Again?
We have very much solved infant mortality. There are still child deaths, but these are now in sufficiently low numbers that even eradicating all remaining deaths will have insignificant further impact on population. Therefore the exact same problem will not reoccur, however there medical advances that result in longer lives would increase the number of people alive at any one time. As the elderly do no currently reproduce, the impact is a one time increase, rather that ongoing population growth, however if these secret of living indefinitely is ever revealed, then we reach a whole new overpopulation problem.
Step 5 is: Understanding there was an explosion, and it was clearly driven by the reduction of infant mortalities.
6. What Ended The Explosion? Solving The mystery of Falling Birth rates.
Understanding that the population explosion was ended by falling birth rates raises a huge, and unanswered question:
What caused the fall in birth rates that brought an end the population explosion?
It is huge because without an answer, the future is dangerously unpredictable. It is unanswered, not because there is no answer, but because people are not agreed on a correct reason to be the answer.
Unlike a boom caused by a temporary increase in birth rates, a boom caused by increased child survival cannot happily end by having things return to how they were before. We do no wish to return to high infant mortality to end a population explosion. Falling birth rates is a better solution, but a puzzling one. Now we have two changes. Reduced infant mortality and reduced birth rates, but the reduced infant mortality was intentional, while for the most part, reduced birth-rates occurred without specific intent or even necessarily obvious reasons.
There are several suggested reasons including:
- Family Planning programs and measures by governments to reduce population.
- The availability of birth control.
- The education and changing role of women in society.
I discuss each of these in Why are birth rates falling?
Generally, the answers have problems. Yes, some countries, notably China, took steps to reduce birth rates, but most countries took no steps, and still have falling birth-rates, so steps to reduce birth rates are at best a partial explanation relevant only in some cases.
The most commonly accepted explanation is that factors not planned to lower birth rates, and not directly linked to the population growth explosion, are central to returning population growth back to historically normal levels.
The other possibility would seem to be that the reproductive instincts of humans, like other animals, is a drive designed by evolution to produce a sustainable population. We seem to think there is some logic that makes humans decide to have a specific number of children, or to fall in love in the first place, and even to love our children. In reality, surely these are not logic, but things we have evolved to be driven to do. And if so, it would seem logical that we are driven to produce an appropriate number of children.
That such factors play a role is the only explanation for throughout history people having an appropriate number of children.
7. Finite Population: We Evolved to Reach A Stable Population Plateaux.
The next step for me what a light bulb moment arising from thinking again about those historical levels of growth, that for so much of human history had to be close to stability. Then comparing this with what happens in nature.
Gorillas in the mist tells the story of a population of gorillas that appears to have been stable for thousands of generations. Yes species, including gorillas are capable of population growth that would over time result in incredible numbers, but instead seem to quickly reach a ‘population plateaux’ or stable level.
Just three children per family surviving to have their own family would result in population growth sufficient for a population doubling every 50 years. Clearly while this has happened during the last 200 years, historically humans rarely average 3 children living to have their own families, because if just this rate continued for just 3,000 years of the 300,000 years humans have existed, we would have 9,223,372,036,854,775,808 humans, which is over 18,000 humans for every square metre of the surface of the Earth.
On a finite planet that is even 500,000 years old, every species on the planet has had sufficient time to completely overrun the planet. This means every species has way more time than need to reach it resource constraints, and for those that can exceed sustainable constraints, to exceed constraints and reach a catastrophic level of overpopulation.
If it was human nature to populate ourselves out of existence, you would think we would have already done so by now. Since almost all animals can exceed sustainable constraints and exterminate their food sources, there has to be a way animals naturally limit reproduction.
Conclusion and Where Next.
In a reversal of the situation back in 2015 when people questioned that population growth would end, we now have stories like this one from the BBC:
The world is ill-prepared for the global crash in children being born which is set to have a “jaw-dropping” impact on societies, say researchers.
Falling fertility rates mean nearly every country could have shrinking populations by the end of the century.
And 23 nations – including Spain and Japan – are expected to see their populations halve by 2100.
Countries will also age dramatically, with as many people turning 80 as there are being born.Fertility rate: ‘Jaw-dropping’ global crash in children being born, BBC 15 July 2020
There are many predictions of population numbers up to 2100, when China, Italy, and Japan will all halve in population and Nigeria will have more people than China. The risk with these projections is do they project based on current trends, or do they predict future trends? The data seems to be the former.
What will happen next? If the plateaux concept is correct, then while the population may fall for a time, it will only continue to fall if that is what appears the right solution for humanity. I guess the next step is to explore just would the right solution for humanity be.