One Finite Planet

One Finite Planet

Population: just how did the ‘engine’ switch off

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I have commented several times on how the ‘engine for global population growth’ has been switched off.  Most of us will have noticed how family sizes have dramatically reduced in recent generations even if we have not linked this to population growth. Many of us have stories of families just one or two generations ago with 7, 8 ,9 or even over 10 children in family.  How often to we see such families now?  The reality is now the average is around two, almost everywhere in the world.  The ‘ageing’ population is widely reported, even if it is less often explained how this ageing is driven by lower birth rates, and thus, lower population growth. Actual population growth is discussed in more detail here.

Those looking at the catastrophic impact the human population is having on so many other species living on earth, and seeing the human population still rising will despair that we are still growing our population.  But as I have stated elsewhere, most of the growth we are still seeing is due to ‘lag’.

But if we have switched off the engine of population growth, just how and why did this happen?

What has changed?

Most of us will observe for ourselves that family sizes have declined.  This is also backed by data.  To quote the Encyclopaedia of Family Health on “Changing Family and Health Demographic:

“During the latter half of the 20th century, family demographics underwent numerous profound changes, and these changes were global in nature. Given the importance of family in contemporary society, it is necessary that the potential impact of these changes be understood. In industrialised countries, the one-earner family became the two earner family, birthrates feel to historically low levels, the proportion of births outside marriage rose rapidly, and marriage became less common or much delayed. In both industrialized and developing countries, a significant quantitative development was the overall decrease in the birthrate and the consequent shrinking of family size.”

In fact looking through the Worldbank data, it seems surprising that most countries are not already shrinking in population, until you understand the ‘lag’ effect.

So why has the birth rate changed? Look up your country, and compare with what you know of family sizes around 80 years ago.

There a lots of theories, but in the end, they are just theories (or in true scientific terms, hypotheses),  because it is very difficult to test any theory.

Certainly governments have tried reducing birth rates in many developing countries with programs to educate on family planning and other steps.  Governments also quote success in such programs, but while results have been encouraging, there have usually also been similar results in countries without such programs.  Governments that have tried programs to re-invigorate birth rates have not seen positive result.  Certainly the one child program in China is the exception in that there seems little doubt this did have an impact.  However China has not dropped the program no such program is required any more for a stable or declining population for China.

So, generally, government intervention does not explain the trend.

What is clear is that in every modern society, with educated women and access to birth control, ‘births per woman’ is no longer an engine to drive population growth.

There are many social factors that can be cited as logical, and it can even be proposed that it is a natural instinctive response to humans realising that population growth must stop. But in the end, the ‘why’ is just untested hypothesis.



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