"Our greatest responsibility is to be good ancestors."

-Jonas Salk

Thursday, September 2, 2010

Demographic Transition: Cause and Effect

The egregious Dellingpole suggests that "as GDP per capita increases, so people decide to have fewer children and that therefore the solution to Africa’s problems is for everyone to be made richer, faster through the institution of property rights, free trade and incentives for local people to benefit from the safari industry and keep those reserves in the pristine state".

A few months ago James A pointed me to this remarkable graph, which I had since lost track of. It isn't actually linked at Wikipedia; it's, for some reason, an orphan graphic. All the more reason to feature it here, as it's a stunning infographic, despite the plain color scheme and the lack of little Bob the Builder icons crawling all over it and gratuitous lines running every which way.

If this is real, it should be widely known. No whole-system analysis of the future can ignore the astonishingly strong correlation between fertility and income.

But that doesn't tell us what to make of it. It is commonly claimed that rich countries stop making babies. But it makes at least as much sense to consider that countries that stop making babies become rich. I don't want to get too deeply into the fraught ethnic tensions of the Southwest, but I will say that the latter theory is certainly the folk wisdom among white southwesterners when considering Mexican and hispano-American culture. Certainly the individual who has children before attaining marketable skills will have a harder time developing them later. That stands to reason.

Now, as with temperature and CO2 on the interglacial time scale, the causation could easily run both ways. Indeed, when the correlation is so tight, we should suspect a positive feedback. But which comes first? Which is the trigger? Which causality direction dominates? Could it be that a decrease in fertility sometimes or often precedes the increase in the wealth?

Compare, for example, the recent history of China vs. that of India.

I am not sure what the implications of this alternative are. I'd like to know if it has been considered anywhere.


Steve Bloom said...

I've seen rather a lot of discussion of this over the years, a key added point being that education of women could be the main thing going on.

William M. Connolley said...

Nice pic. the other point to make is that (if you ignore the blobby bit near 30k, and a couple of obvious outliers like Saudi) the trend from 15k onwards is actually slightly upwards. So it looks like past a certain level of wealth babies start increasing again.

John Mashey said...

When one has 2 variables that correlate, one might assume causation, as in:

"Over the last 50 years, the number of aluminum cans in the USA is well-correlated with the number of lawyers (I think)."

Hmmm, do lawyers cause aluminum cans, or is it the other way around? :-)

Of course, when 2 variables are correlated, they may influence each other, but it may well be that they are influenced even more strongly by other variables.

For example, in this case, I'd swear I posted on this before, but can't find it quickly. Almost everywhere (including the USA), rural farm populations are less rich than those in suburban/urban areas. [From a previous discussion, recall that I'm an old farmboy, although I lack MT's big hat.]

Kids are economically useful on traditional farms, one of the reasons the Amish have ~7 kids/family. Kids are less economically useful for anyone living in a Manhattan apartment, especially if they need to be sent to grad school at some point.

CIA Factbook for China says:
"urban population: 43% of total population (2008)
rate of urbanization: 2.7% annual rate of change (2005-10 est.)"

For India it says:

urban population: 29% of total population (2008)
rate of urbanization: 2.4% annual rate of change (2005-10 est.)

Let's try a few others:
89%, 1.2% Australia
85%, 0.5% Sweden
82%, 1.3% USA
74%, 0.1% Germany
61%, 1.4% South Africa

22%, 4.0% Kenya
18%, 4.2% Rwanda
16%, 4.0% Niger
10%, 6.8% Burundi

Now, this isn't a random sample, and I've never seen the 3-axis chart of per-capita GDP, fertility, and urban%, but I'll bet urban% correlates fairly well with both per-capita GDP and with lower fertility...

Now, as to why this might be an issue, one of the reasons the USA got rich was:
1800: 80% farmers
1900: 40% farmers
2000: 1-2% farmers
[Those %, of course are different from rural%.]

So, how did that happen:
a)Mid-West and Far West, esp. California replaced NorthEast farms, the former having great soil, courtesy of Canada.

b) and that happened in part from horses that made the mid-West

c) and later, from having good rail networks, 400HP combines, and the rest of the infrastructure to let a relatively tiny number of people grow enough food for the rest.

As a minor issue, horses and tsetse flies don't mix well, many African soils are too poor for large-scale farming, and even a little tractor is far beyond most people's means, even if they could pay for the gas to run it, and if they had roads to ship their produce very far. [The late Norman Borlaug thought transport was really, really important.]
In an era of the peak Oil downslope, what are the chances African farmers will increase their oil usage?

SO, Delingpole is often wrong, but in general, nowhere in the world are small;-scale farmer very rich...

John Mashey said...
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John Mashey said...
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John Mashey said...

Sorry for dups, I was getting a weird message that said it was too big.

Michael Tobis said...

I really wish blogger would quit doing that. I will be moving to wordpress shortly, methinks.

Anna Haynes said...

> "I will be moving to wordpress shortly, methinks"

Not wordpress.com, I hope, given the experiences of Tamino and frankbi.

As for the graph, recall Hans Rosling's TED talk/demo along the same lines

Anna Haynes said...

If you have Social Security, you have less need to make progeny to support you in your retirement.

Ugo Bardi said...

I have right now in my hands a copy of the 1972 book "The Limits to Growth". At page 112, you can see the same graph shown in the blog; in a version made in 1970 by the US agency for International Development. The data have changed a little, but the general behavior is the same. This curve has been included in the "world 3" model, already in its 1972 version, in order to calculate the population behavior over the 21st century. According to some recent evaluations by Turner, the model has worked very well up to now.

So, the knowledge that wealth correlates inversely with birth rate idea is not new, it is at least 40 years old and perhaps older. And Delingpole is basically right in saying that if we could make Africa rich, then Africans would stop making so many babies. How to do that, in practice, is another matter, of course.

Besides, there are several interpretations of the curve and according to some demographers it is a transient result of the growing phase that has been ongoing during the past century or so. Hence, we don't know if the curve will remain the same if we enter a sustained period of economic contraction.

It is an awfully complex matter and it is too easy to produce wonder-solutions as Delingpole does: "just make Africans rich!" Yeah, so easy.....

Anonymous said...

A somewhat related discussion came up in comments on a post I did about popualtion growth, e.g.

A collegue of mine makes a related point that the widepsread use of artificial fertilizer made it possible for world population to grow the way it did (by increasing the agricultural yield).


Michael Tobis said...
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Michael Tobis said...

My question is whether we should not instead suggest that we should encourage the Africans to be less fertile, thereby enabling them to get rich! I am, of course, not disputing which side of the curve we prefer.

Martin Vermeer said...

Actually this is very old knowledge, and I'm surprised that people are surprised by this! I read about this in high school, back in the nineteen sixties. A classic text by a French demographer (having long since forgotten his name; that long ago).

It is as Steve Bloom says: the key factor is education, especially of women. Here.

Ugo Bardi said...

Ouch, Mike, now that you said that,"we should encourage the Africans to be less fertile" you'll be tagged forever as an enemy of humankind.

I know this - the reason I had in my hands the 1972 edition of "The Limits to Growth" and I am writing a whole book about the story of the study and its demonization. One of the reasons for its fall from grace was that the authors had gently hinted that population growth could be slowed down or even stopped by non violent and non oppressive means.That was used to say that they were organizing a world dictatorship with the purpose of exterminating the darker races (I am not inventing this)

Incidentally, in the demonization of "The Limits to Growth" we see the same methods used today against climate science - even some of the same people!! But now, they are much better at that - unfortunately

Michael Tobis said...

Ugo, please let me know when it is published! I will be pleased to pass that along to my readers.

PS - I go by "Michael" or "mt" or in extreme cricumstances "Dr. Tobis"; other names (e.g. "Mike") are not recognized.

Michael Tobis said...

Martin, I'm aware of the concept. I was not aware of how good the correlation between wealth and fertility is until I saw the graphic.

The Wikipedia article does not really address this correlation. The causality I propose (which, again, is folk wisdom in these parts) is not addressed. Perhaps academics in America shy away from this question precisely because it is folk wisdom that is attached to ethnic tension, but maybe somebody in Europe has taken note of the possibility.

John Mashey said...

One more time:
1) Subsistence farmers are *never* rich.

2) Neither are small family farms, although they can at least be comfortable is:
a) They are excellent farmers, have horses, and ~7 children/family, and some off-farm jobs, like the Amish, who typically do 40-80-acre farms, I think..
b) They are excellent farmers with electricity, tractors, good soil, water, have access to good seeds and fertilizers, and transport network necessary to get access to markets. Even then, they may have trouble competing with those 400-acre family farms in the mid-West, which only work with combines. Industrial farms are another game indeed. Of course, migrant farm workers don't get rich either.

As much as I'm for educating women (I've often heard: "Teaching calculus to girls is good birth control, doesn't work for boys", and as much as birthrates come down when people are richer...

I think most of this discussion is *simply irrelevant* unless people either:

a) factor in the realities of agriculture and rural-vs-urban population
b) Show that it's irrelevant.

In general, it is very difficult for large numbers of a society to get wealthier, UNLESS:

c) You can raise the agricultural productivity/person, which lets farmers make more money. [USA prosperity, in part, derives from land-grant universities that are often centers for state ag extension services that have long promoted better farming techniques. A lot of our big state universities started as ag schools.]

d) That lets more people do something else than farming.

But I claim that without addressing this issue, trying to treat this as a 21-variable problem is simply a waste of time.

Michael Tobis said...

John, excellent points. But they don't directly address my question, which is whether the causality runs the other way, and if so, how much. In other words, if people reduce their birth rate, do they become richer?

I suppose your answer is simply "no" under subsistence conditions, and that's more than plausible.

Note, though, that there are substantial conurbations in the developing world. Metropolitan Lagos has 15m people. Mexico City 21m. Mumbai (Bombay) 21m.

Ugo Bardi said...

I still need to understand some fine points of the Imperial Language. Some Michaels like to be addressed as "Mike", some don't. There has to be a reason.

About the book on "The Limits to Growth", it should appear before the end of the year, published by Springer

David B. Benson said...

An Amish farmer was asked why, given he seemed to have plenty of spare time, he didn't double his operation to 80 acres.

"I'm not smart enough to farm more.' was the reply.

Bares (or bears) thinking about.

John Mashey said...

MT: I'm in too much of a crunch finishing up giant tome on Wegman report, but the *main* points are:

1) Given 2 correlated variables, one must be very careful to assess any influence of other variables. The usual example is that in the US, after 1950, the # of lawyers and # aluminum cans are correlated. Now, do cans cause lawyers, or the reverse?

2) Of course there are big 3rd-world conurbations, and that points out that to get serious, these country wide GDP/person and fertility ratios are fairly useless. One needs those at least split rural/urban, plus migration rates. When I've looked at this in the past, I've used data like USDA on Iowa, which you can get by state. It at least has rural/urban populations and income levels of time, plus education ... and it is a reasonable sample. People in urban areas are better educated and make more money.

It doesn't have fertility numbers, and in all these cases, one has to be careful to include migration numbers. In many places, the urban birthrate is lower rural (for whatever set of reasons), but the cities keep growing because of migration.

Anyway, I am just saying that the question "does wealth cause lower fertility or vice-versa" is a mis-framed question in the presence of at least 2 strong other variables, even ignoring the social security issue someone mentioned:

a) Rural/urban split.
b) for the rural side, what sort of farming is there?

[Because, for subsistence farms or Amish farms, having a bunch of kids is a big plus. If you have a big farm in Kansas, run as serious (and often pretty high-tech) business, and you expect kids to go off to college, perhaps to study agronomy and later come back and take over the farm ... you have a different idea of the number of kids you might want.]

Padraig Tomas said...

Michael raises the question of if …

"...we should encourage the Africans to be less fertile, thereby enabling them to get rich!"

A brief look at the data on the CIA fact book website will yield all the information needed to satisfactorily answer the question. The three countries in the world with the worst life expectancies are Angola, Zambia, and Lesotho. They are also the three counties with the worst death rates in the world, ranked in order they are Angola, Lesotho, and Zambia. Angola has a median age of 18. Zambia has a median age of 16.5. Lesotho has a median age of 22.6. These three counties (Angola, Zambia, and Lesotho) have fertility rates of 6.05, 5.07, and 3.00 children, which compares with 2.58 for the world as a whole. The infant mortality rates are 180.21, 101.2, and 77.4, per 1000 births respectively. The rate for Angola is the highest of any country in the world. Also of interest are the rates of HIV infection for the adult population. Angola has a 2.9% rate of infection which is quite bad. It is 29th worst in all the countries of the world. Zambia has a 15.2% rate of infection which is the 7th worst in the world. Lesotho has an HIV infection rate of 23.2% which is the 3rd worst such rate of infection. The notion that we could expect that reducing the birth rate would have any material impact in improving the lives of the people in these counties strikes me as implausible.

If something could be done to improve the life expectancy and infant mortality rates that would have an impact. If real wealth could be generated that would have an impact. If just government could be established that would have an impact. If the expectation of an early death could be nullified that would have an impact.

When people’s lives are short, and the children die frequently, lower birth rates will yield the death of families, and villages, and towns, and nations. I don’t see how it could be otherwise.

There is also the question of how such policies would be seen. Would they not be seen as being heartless and bigoted?

guthrie said...

Ahh, thus we see Delingpoles agenda, never mind that countries which develop well actually don't use free trade in a simplistic manner that he suggests and often make compromises on property rights for the greater good.

IIRC the demographics of the UK well enough, the fall in births was correlated with the increase in urbanisation, fall in infant mortality and increase in living standards. It takes place over several generations, such that more and more people realise that they don't need to have 4 children to be sure that 2 survive; they don't need 4 children to work the farm, thanks to mechanisation they need only 2; thanks to social security the cost of illness and accident is shared, so you don't need extra breadwinners running around to make the necessary pennies to keep you alive and in your accomodation.
If you descended from on high and gave the farmers modern equipment (lets assume it all worked fine), you could perhaps reduce it to a generation,with those who are children when you do this growing up and having only 2 or 3 children.
But thats pretty much impossible.

Come to think of it my grandparents and great grandparents generations kind of back up what John Mashey is saying - the side from the coutryside regularly had 4 or 5 or 6 children, the ones who were much more urban had only 2 or 3.

John Mashey said...

Note of course that it isn't just modern equipment, it is:
a) Improved-yield seeds, well-adapted to the local conditions [which is why there are many varieties]. Note that this was a big piece of Borlaug's Green Revolution.

b) Constant need to upgrade them to deal with changes in pests and problems like wheat rust, which is really, really bad stuff, and it mutates, and fighting it currently means planting lower-yield varieties.

c) Farming techniques in general.

d) Energy, which in USA is some mix of electricity and fossil fuels, plus some biofuels in some places. (in Brazil, more biofuel from sugar cane). Of course, gas/diesel requires infrastructure to get it to farmers, as one really does not want to drive the tractor into town every time you need to fill the tank ... so of course farmers normally have their own tanks. We certainly did. But those require roads good enough for at least little tank trucks to come. One also needs the support infrastructure to maintain vehicles.
SUMMARY: most poor African farmers will *never* have the current-world fossil-based farm machinery ... but then the developed-world won't either. We'll have to go to mostly electric vehicles, with biofuels for the cases where you can't. (I'm not sure how to do electric 300HP combines.) just as Africa & India have skipped telephone landlines in favor of cell-phones, maybe, just maybe, they can skip the fossil-machinery stage to electric tractors that can be recharged locally, require much less infrastructure to support, are simpler and easier to maintain.

e) Of course, there is still the issue of fertilizer, which is not free, and much of whose current from is not indefinitely sustainable.

Again, the reason for banging on this is that large numbers of people in developed, organized societies simply take food for granted...

Michael Tobis said...

I find it difficult to believe that the curve is very complicated since the result is so striking. But on the other hand, wealth should probably better be plotted on a log scale; maybe the picture would be messier.

But the point is taken, let's see how urbanization fits in.

I find Patrick's focus on extreme cases to be not a good way to understand the structure of the curve. It's really the places in the middle that will tell the tale.

Michael Tobis said...

Gapminder has all three variables: per capita income, fertility and urban percentage. I have been playing around with various ways of plotting them but nothing spectacular jumps out at me.

I will say that my impulse to put income on a log scale is probably right. It does make the tale more complicated, though.


guthrie said...

JOhn Mashey - I know a bit about how dependent we are on all the things you mentioned, simply because I like to know how things work. (Shame I can;t seem top turn that into a job). BUt most people I know don't know much about it at all, for various reasons.

Then there is the issue of politics. What I've read (Admittedly probably not a broad selection) over the last decade show that the approach that the likes of Delingpole mindlessly parrot doesn't work. Apparently the kind of crop research institutes required in developing countries have tended to be defunded because they are usually gvt institutions. Meanwhile the large corporations spend more on genetic modification ofcrops than it costs to keep the old ones up to date with disease and drought etc resistance, except this work isn't being done as much as it should be.

Then of course we have cloned bananas.

But I'm not sure how we can get enough of the small underdeveloped countries up to more modern standards during peak oil. One of my ex-work colleagues is from Ghana, which seems to be developing nicely, but they don't necessarily seem to be thinking so much about the future yet. Is there any replacement at all for modern tarmacadam roads that doesn't require massive maintenance every year or two?

John Mashey said...

MT: re gapminder
Thanks! I'd see that a while back and couldn't remember its name.

But in any case, I think the main message of all this is that one has to be careful of 2-variable charts in the presence of possible 3rd and more correlated variables (like the urban/rural split I suggested, and the industrialization / infant mortality / social security) changes others have noted. Along these lines, one also finds infectious diseases =>lower IQ, and of course there is some correlation between IQ and GDP...

David B. Benson said...

Reread Jared Diamond's "Guns, Germs and Steel".


EliRabett said...

Anna has it pretty much right, if you don't need kids to take care of you when you are old, there is not so much pressure to have lots of kids.

That being said, IEHO it runs pretty much like this:

At the beginning, infant and child mortality is high, you need kids to take care of you in old age, and as importantly to help with the farm, earn money to support the family, etc.

After infant and childhood mortality decreases because of cleaner drinking water, vaccination, etc. you don't need to produce as many kids to ensure that they will be there to help.

At that point you can get a bit ahead of the game and build some capital.

As the society gets rich it brings evils such as social security, so you need fewer kids.

Padraig Tomas said...

I have not played with Gap Minder, but I have made use of Google Labs - Public Data (http://www.google.com/publicdata/directory) which has an interactive graphing feature. Gooogle Labs uses data from the world bank.

This chart is of interest:


It is also suggestive that of the three countries that I made mention of the one with what seems an anomolous fertility rate has a very high female literacy rate.

Country Female Literacy Fertility
Angola 53.8% 6.35
Lesotho 94.5% 3.33
Zambia 74.8% 5.07

If we wish to stabalize the population of a given country, or region, or the world as a whole. It would be worth while to see what the countries that have done so have in common, or not as the case may be.

With regard to the extreme cases (Angola, Lesotho, and Zambia) which I have looked at they are rather less extreme in the context of Africa than it might seem.

The UN has a rating which is applied to some countries, when looking at what is called human development. I refer to the index of Least Developed Countries, these are countries which have extreme weaknesses in terms of low income, human resource weakness (poor nutrition, excess morbity, inadequate education, low literacy rates), and economic vulnerability (instable agriculture production, inadequate capitalization, infrastructure). Of the 49 least developed countries 33 are in Africa.

While using Google Public Data Explorer I found that of 46 African countries in the data base 30 had per capita GDPs less than or equal to 1090 dollars a year.

All of this points toward the conclusion that in Africa the extreme cases are more usefully seen as the norm rather than outliers.

If anything would be a magic bullet it would be universal literacy, and compulsary education.

Anonymous said...

Dear Colleagues:

As humanity's most luminous beacon of truth, science provides us with a last best hope for the survival of life as we know it on Earth. We must make certain that scientific evidence is never downplayed, distorted and denied by religious dogma, politics or ideological idiocy.

Let us not fail for another year to acknowledge extant research of human population dynamics. The willful refusal of many too many experts to assume their responsibilities to science and perform their duties to humanity could be one of the most colossal mistakes in human history. Such woefully inadequate behavior, as is evident in an incredible conspiracy of silence among experts, will soon enough be replaced with truthful expressions by those in possession of clear vision, adequate foresight, intellectual honesty and moral courage.

Hopefully leading thinkers and researchers will not continue supressing scientific evidence of human population dynamics and instead heed the words of Nobel Laureate Sir John Sulston regarding the emerging and converging, human-driven global challenges that loom ominously before humankind in our time, “we’ve got to make sure that population is recognized.... as a multiplier of many others. We’ve got to make sure that population really does peak out when we hope it will.”

Sir John goes on, “what we want to do is to see the issue of population in the open, dispassionately discussed.... and then we’ll see where it goes.”

In what is admittedly a feeble effort to help John Sulston fulfill his charge to examine all available scientific evidence regarding human population dynamics, please give careful consideration to the following presentation and then take time to rigorously scrutinize the not yet overthrown science from Russell Hopfenberg and David Pimentel regarding human population dynamics and human overpopulation.


Please accept this invitation to discern the best available science of human population dynamics and human overpopulation; discover the facts; deliberate; draw logical conclusions; and disseminate the knowledge widely.

Thank you,

Steve Salmony

Steve Salmony said...


Steve Salmony said...