Is the population boom a bust?

Checking in with Malthus

Now exceeding 7 billion, the world population has been rising by nearly a billion souls per decade.  True, the growth rate has nearly halved since 1960, to 1.2% per year.  But the poorest populations have been growing at almost double the world rate.  They account for almost a fourth of the addition to world population although they comprise only an eighth of the total population.  Five African countries are growing by 3% or more per year, including Zimbabwe (3.1%).  The Palestinian West Bank and Gaza Strip also grow by 3%.  No wonder demographers suspect that population growth creates poverty, although the most rapidly-growing nation, the small Gulf state Oman (9.2%), is rich, according to World Bank data.

In Soviet days, Soviet scholars fearfully anticipated rampant growth throughout the Central Asian satellites.  That hasn’t transpired.  Three countries grow at the world rate or slightly lower: Kazakhstan, Kyrgyzstan and Turkmenistan.  The largest populace in the area, Uzbekistan, is growing faster (1.5%).  But the pacesetter for the region is its poorest nation, Tajikistan (2.2%), in line with demographers’ expectations.

A simple model, assuming a constant rate of growth, predicts more than 90% of the fluctuation in population for most nations over a period of 10 or 15 years; after that, the growth rate tends to change.  This suggests that a simple theory may explain the size of population – and Thomas Malthus provided one, in 1798.  One of the first professional economists, Malthus argued that population growth doomed humanity since the populace would expand more rapidly than food supply.  The amount of food per person would fall until we starved.  Famine, pestilence and war would thin the population, raising the amount of food available to each survivor until people had recovered enough to beget children again.  Then food supply per capita would fall back to the subsistence level. 

Charitable cruelty

We cannot escape this cycle of catastrophe because – according to Parson Malthus -- we cannot control our passions.  Consequently, the rate of population growth will be determined largely by the fertility rate (the number of children born to an average woman), which changes slowly.  (From 1965 to 2008, the fertility rate in Kazakhstan fell just 27%, from 3.49 to 2.56 – but fell as low as 1.8, in 1998 and 2000.)  So it’s no surprise to find that most populations grew at a constant rate over the medium run.  Food supply, on the other hand, depends on a finite amount of land, so it grows linearly – that is, at a diminishing rate.  The populace grows faster than the harvest.

Malthus’ dark vision extended to altruism.  He opposed welfare for the poor since it would merely encourage them to have more hungry children.  “Such charity was only cruelty in disguise,” explained Robert Heilbroner, the late historian of economic thought.

China adopted a Malthusian policy in 1979, when it forecast a spike in fertility in the 1990s.  Parents with just one child received priority in health, housing and education.  Those with more than two children were taxed 5% of their income per child; the rate increased with each additional child.  The policy may seem a success:  Since 2000, China’s population has grown by less than .6 of a percent per year, half of the world average, and the fertility rate fell by two thirds in less than 30 years.  But China’s sizzling economic growth may have played a role, too.  Richer households have fewer children, perhaps partly because they would have to give up high wages in order to devote time to the bambinos.  In any event, the policy incurred social costs.  In 1986, one child was aborted for every two births. 

Calling Dr. Pangloss

Though compelling, Malthus’ theory does not fit the facts.  Since 1798, both the world population and world income per capita have grown sharply.  Latter-day Malthusians, such as the Club of Rome, warn that catastrophe is just around the corner; witness global warming.  Nevertheless, the past two centuries have given us a pretty good dataset.

Anti-Malthusian economists explain that an increase in population density stimulates innovation, since more people can exchange more ideas.  Whatever the reason, some nations would welcome a population boom.  Russia lost five million souls from 2000 through 2009, when its population dipped below 142 million, though it has grown slowly since then, to 143 million in 2012.  An indicator of the future labor force, the share of the population younger than 15, fell from 1990 through 2004 in China, Japan, Kazakhstan -- and sharply in Russia, from about 22% to 15%.  Maybe two heads are better than one, especially if one head is young. --Leon Taylor tayloralmaty@gmail.com

Notes

1.  The growth rates of national populations reported here are annual averages for the period from 2000 through 2012, using World Bank data.  I estimated them with this OLS model:  Ln Pop(t) = a + r*Year, where ln denotes a natural log and r is the exponential rate of growth.  R-squared for most estimations exceeded .92 and usually exceeded .99.
2.  Concerning the fertility rate in Kazakhstan: A measure of volatility, the ratio of the standard deviation to the mean, was .21 – lower than one might have expected, given the dramatic changes due to migration over the 1990s, and given that there were only 25 observations for the 44-year period.  

Good reading

Karen Hardee, Zhenming Xie, and Baochang Gu.  Family planning and women’s lives in rural China.  International Family Planning Perspectives 30(2): 68-86.  2004.  A source of the material used here about China.

Karen Hardee-Cleaveland and Judith Banister.  Fertility policy and implementation in China, 1986-88.  Population and Development Review 14(2): 245-286.  June 1988.  Another source of the Chinese material.

Robert Heilbroner. The worldly philosophers.  Touchstone.  Seventh revised edition.  1999.  Depicts Malthus vividly.

Thomas Malthus.  An essay on population.  1798.  Online.  Brilliant and provocative.

Joseph Schumpeter, Capitalism, socialism and democracy.  Harper.  Third edition.  1950.  Argues that returns to producing ideas do not diminish as ideas increase, because they don’t require finite resources – just imagination.

References

United States Bureau of the Census.  International data base.  2013.  The source of estimates of world population used here.

World Bank.  World Development Indicators.  2014.  Online.  The source of estimates used here for population levels, fertility rates, and the share of youths in national populations.