Wednesday, August 22, 2012

A second note on the import of statistics












Anonymous said...

I really don't think Nigeria will ever obtain the population that is projected based on simple extrapolation of present trends. There is no way that 750 million people will be able to feed themselves in Nigeria.

Such projections ignore real limiters on human population growth, that of food and water. And of course as population pressures increase, war, disease, will play an increasing role to bring things back into balance.

Real life is much more than trend lines.

jemand said...

In reply to anonymous... I also am skeptical that the population could get to 750 million and by supported by the land in Nigeria... but I'm also skeptical that anything like famine or war could avert it.

WWII only killed 60 million worldwide, the largest famine of the 20th century was perhaps the Chinese one during 1960 or so, and only killed at maximum about 40 million.

I just don't really see something even that big likely to happen in a country such as Nigeria which has oil and is, though corrupt, not closed off from the rest of the world in trade. And it looks like it would require disasters on a much *larger* scale than anything we are familiar with to even slow down the demographic trends a little bit.

It's complicated by the fact that Nigeria is only a quarter the size of India, so 750 million on that land is already double India's maximum density and it looks like the trend is still just going up at 2100, and it's neighbors are also growing quickly. I have no doubt it would be seriously in excess of the local sustainable population. But, local overshoots of carrying capacity are completely possible, and we just don't have any examples of how a modern country's demographics might be derailed by war or famine-- really the only things that seem to have any effect on this scale are social changes in the expected family size.

Colin said...

@jemand: There is a plausible Malthusian equilibrium: one where the population is perpetually under-nourished, causing especially high death rates among infants and greatly reducing women's ability to conceive and carry pregnancies to term (and also increasing their risk of dying). Plus everyone has a weak immune system, so epidemics hit much harder. This was basically the state of play throughout the world in pre-industrial times.

If you're looking for historical examples of sudden spikes in mortality, forget wars and famines. They pale into insignificance compared to the numbers killed or effectively taken out of the reproductive pool in the great pandemics. You don't even need to go far back in history - look at what AIDS has done to southern Africa's demographics, for instance.

jemand said...

Colin, which nations do you mean? I was looking at a few and it seems to me that only Zimbabwe don't have very high recent population expansion rates. Even the ones hit hardest by Aids, still seem to have pretty strong exponential growth.

And I don't really know if Zimbabwe's slowed growth is due to any sort of demographic shock on the order of war/disease/food pressures etc., or if it just has a different social structure which has decided to have fewer children, i.e., demographic transition.

Anyway, I don't have too much time to look into it this morning, but I really am interested in any modern examples of a population, particularly one with a relatively large base, seriously swayed by the "classic" malthusian threats. It looks to me that exponential growth in the absence of demographic transition is pretty naturally the way things go-- we really do have a lot of excess production in the world today and many places can deal with severe reductions in standard of living, even from what we consider an already "poor" lifestyle, even to the extent of many individual lives being pretty disastrously uncomfortable to live... and yet the business of having children just keeps going. Reproduction really takes just a tiny fraction of our productivity these days...

Noel Maurer said...

There are obviously huge problems with population projections on this time frame. Climate change, robots, social mores ... you get the point.

A second comment follows.

Noel Maurer said...

Anonymous appears to making a basic error.

Countries can trade. What matters is whether the world can produce enough food to feed the world population in 2100, not whether any particular country is self-sufficient.

That is, I think, Jemand's point: I'm just making it more directly.

Self-sufficiency, by the way, has many advantages, but averting famine is not one of them.

Jesse said...

@Colin I think that history has shown repeatedly that people who predict a coming population disaster are wrong. Malthus was wrong and people were wrong in the 1960's when they predicted there would be massive food shortages. The thing people always forget is that technology advances much faster than population grows and that always provides an answer to our problems. In the 1960's we had the green revolution that allowed us to produce enough food to feed more people than anyone ever thought possible. Also the ability to ship food from regions of excess (the United Status or Russia for example) to regions of scarcity (like Nigeria) shouldn't be overlooked.

Jesse said...

This is a great article. It think that the comment about power shifting away from the West and towards Asia and Africa is spot on. By sheer virtue of demographics Asia and Africa will increase in importance. If you look at the countries that have been doing the best economically it is the developing countries with a young and growing population. The developed countries with aging and declining populations have been struggling economically (mainly Europe and Japan). Without a growing consumer base eventually you reach a point that you can't grow any further. Then once a countries ratio of dependents to workers gets to high they begin to run into debt problems. The only way out is to increase the population. Unfortunately most of Asia appears to making the same mistakes as the West and has a sharply declining birth rate.

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Anonymous said...

Looks like WW3 will be in africa