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Of pigs, pythons and population growth – setting the record straight

Maitreyi Bordia Das's picture
The Nairobi Central Business District.
Photo: Sarah Farhat/The World Bank

I am constantly startled by references to “population growth” as a cause of a number of development challenges.  Whether it’s urbanization, food security, or water scarcity, all too often “population growth” is cited as a cause for pessimism or even a reason not to strive for progress.  I can almost see Thomas Malthus grinning at me from the shadows.

It gets worse. I recently reviewed a paper where higher fertility among minorities was touted as an explanation for their poverty! A few months ago, a respected professional wrote asking why we weren’t doing more on family planning, since fertility in Africa would pretty much stymie any efforts to provide infrastructure-based services! I hear statements to this effect routinely from policy makers in charge of infrastructure ministries and projects (“how can we keep up with the population?” or “nothing we do will be enough unless we control the population”) but am always amazed when I hear them from scientists of different hues.

So I thought I’d try to set the record straight:

  1. Basics first: Fertility is declining across the board. But despite a projected secular decline, the momentum will stay robust until the cohort that is now about 10-14 years old, “exits” (or dies off to put it bluntly!).  So, we won’t see the effects of fertility decline on absolute numbers until the “pig leaves the python”, as we demographers say. If you want to understand what’s really happening with population growth and its ultimate stabilization, watch the iconic Hans Rosling in this delightful film
  2. Restating the obvious: Africa is very heterogeneous. Fertility in Africa is projected to decline to 3.9 children per woman by 2030 (from about 4.7 during 2010-2015) and down to 3.1 children per woman by 2050. The highest fertility is in sub-Saharan Africa, with Southern Africa having fairly low levels by comparison.  So yes, Africa does indeed have the fastest growing population. but not “uncontrolled” fertility (except in very few countries).  Family planning, child survival, and female education will have huge impacts on the highest fertility countries, but the trajectory of most other countries is a declining one already. 
  3. Here’s the real challenge: the intersection between fragility and fertility runs deep and stays strong.  Of the top ten highest fertility countries, nine are in Africa, and eight of those are listed as being fragile. There are several reasons for this:  women everywhere want to have control over their fertility, but in fragile situations, they don’t have access to birth control, and there’s a high “unmet demand” for contraception. It may well be the case that these are also high infant mortality regimes, and fertility may be a strategy for risk mitigation.  

    So, fertility is highly correlated with crisis, uncertainty, and poor access to services.
  4. Yes, of course numbers matter: Food and water scarcity, pressures on urban transport or on roads are correlated with how many people there are. But as a brilliant primer from the Population Reference Bureau alludes – it’s not about “over-population” but about bad management of scarce resources. As I have said before, in the case of water and food, it is largely an issue of allocation – both the efficiency and equity sides of allocation. 
  5. So, what’s really messing with infrastructure?  It often depends on whom you ask – the causes range from financing to availability of land and resettling people in densely populated areas.  But why do infrastructure based services affect some people more than others? The short answer is: poor management and the politics behind it! Policy and its implementation are often not accountable to those who are affected by scarcity the most.
Thankfully, others are also tackling the myths head-on – I’d like to recommend Nick Eberstadt’s five myths about global population.  Let me know what you think.



We are focised on the wrong issue. We should be concerned with the theft of Africa's resources. How can Africa with all its gold, oil and diamonds be poor. There is nothing wrong with Africa's fertility.

Submitted by Rob Harding on

Dear Maitreyi,

I believe you are mistaken and hope you will reconsider given that you are in a position at an influential organization with a broad audience - and thus have an opportunity to help us prudently change course.

While I generally agree with several of the points you made in this post, rejecting the negative effects of rapid population growth (and existing overpopulation in many countries, including the US) while placing the blame solely on poor allocation, management and politics is like concluding that the length of a rectangle is the sole contributor to its area without considering its width. With all due respect, that is an absurd argument.

Lastly, it's well past time to move beyond correlation to causation when discussing the number of humans, various levels of consumption and waste generation around the world, and their impacts on food and water scarcity, strains on infrastructure, biodiversity loss, global warming, etc..

Please reconsider your position.


Submitted by Chris Eastaughffe on

Dear Maitreyi,

Whilst from an academic point of view much of what you say is correct, as an overall global assessment it seems you miss the massive increase in WORLD population, and the corresponding rising demand for resources and 'things', which correlates to our rising energy use and pollution costs.
I am not sure why you see the argument that, at a nucleus level, a larger family may be restricted in the amount of money that can be spent on each child, and the global cost to the family budget of larger numbers of children is greater, hence may be 'poorer' on that basis. In simple terms that is observable in many societies.
There is also the issue of 'equitable' distribution of food and water.... given that control is power, and all countries have those who seek power and control, no matter their government structure, equitable distribution assumes forces that do not exist.
The only way there would be an exception to this would be a world government who intended to create a totalitarian dictatorship, and set 'limits' on the allocation and redistribution of resources, based on population... Is this where your argument is headed?
We have a society, and banks, that worship 'growth' hence the drive towards two income families when growth was not enough with a single working parent (IMF policies) in more 'developed' economies. Our current system stagnates when growth stops (Japan being a case in point).
So despite your noted points we need to address the lemmings progression of world population, and the costs of same, as exponential growth, logically, cannot exist forever with finite resources, and our debt based financial system which is pivotal in modern society fails when growth fails.

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