In the early 19th century the Reverend Thomas Malthus, foreshadowing Charles Darwin, wrote:
Throughout the animal and vegetable kingdoms Nature has scattered the seeds of life abroad with the most profuse and liberal hand but has been comparatively sparing in the room and the nourishment necessary to rear them. The germs of existence contained in this earth if they could freely develop themselves would fill millions of worlds in the course of a few thousand years. Necessity, that imperious all pervading law of nature, restrains them within the prescribed bounds. The race of plants and the race of animals shrink under this great restrictive law and man cannot by any efforts of reason escape from it ... Wherever therefore there is liberty the power of increase is exerted and the superabundant effects are repressed afterwards by want of room and nourishment.This is the Malthusian trap: any improvements in institutions, technologies, or any other improvement in labor productivity will over the course of a few generations increase the population until it once again flirts with subsistence levels.
Delayed marriage and plagues can delay or reverse such population growth for a time and produce higher than subsistence standards of living, but, with some small variations (see diagram below), eventually our Darwinian proclivity to procreate will return our descendants back to subsistence levels.
But just as Malthus was writing, his Great Britains were becoming the first living things to ever break free of the Malthusian trap. As a result, in the 21st century the developed world has both populations and standards of living never before achieved.
We can picture the progress of civilization in Malthusian terms. Click to enlarge and examine this schematic diagram:
Click to enlarge.
In this chart, the horizontal axis represents, on a logarithmic scale, the human population per area of land adjusted for natural (but not artificial) variability in its potential to support human food production. Such an adjusted area is typically called by ecologists a "global hectare" and my phrase "natural global hectare" represents a hypothetical measure of this independent of all human labor and capital improvements.
The vertical axis represents per capita nutrition derived, via human labor and capital, from this ecology.
The slope line or "labor productivity isocline" represents, intuitively speaking, a level of civilization. In other words, a level of technological and institutional progress. More specifically, it represents food production output per worker (productivity) adjusted for the marginality of ecology being used. As the isoclines move up and right, a given unit of labor is producing more human nutrition from the same global hectare. So our own 21st century agriculture is far more productive than 19th century British agriculture, which in turn was far more productive than medieval European agricultural, which in turn was more productive than Neolithic agriculture, which in turn was more productive than hunting and gathering.
As we move along a given isocline (a given "level of civilization" as just described) we experience the Malthusian tradeoff: more population per global hectare with lower nutrition, or less population per global hectare with higher nutrition. As we escape from the Malthusian trap, nutrition itself becomes satisfied and the left axis really represents a more general per capita income. Prior to escaping from the Malthusian trap, nutrition dominated the average human budget with fuel (mostly to cook food), clothing, shelter, etc. usually less than 20% of a personal budget or the overall economy.
A number of interesting patterns emerge from this kind of analysis. First, roving bandit societies such as hunter-gatherers and pastoral nomads tended to have lower population levels and higher per-capita nutrition than stationary bandit societies (settled agriculture). The Western European Dark Ages is an interesting intermediate case. This certainly suggests that most prior analyses of Malthusian tradeoffs, which have focused on pure economics, are very incomplete -- that security and politics play a crucial role, and not just in the trivial sense wars and other causes of mortality. There are good reasons of security of property and capital investments to expect this difference between roving and stationary bandits, as I hope to describe in future post(s).
The main question I hope to answer in forthcoming posts is: why did our escape from the Malthusian trap happen when and where it did, and not elsewhere? This will probably involve exploring a wide variety of technologies and institutions and especially the key factors of capital investment and security.
One obvious possible answer -- and the most likely reason humans will continue departing from the Malthusian trap for some time to come -- is birth control. But the British population up to the late 19th century was booming and seldom made effective use of birth control, so this can't explain Great Britain's initial escape from the Malthusian trap. A second answer is to invoke the industrial revolution. But this is a vague term and risks getting at least some of the causation backwards, as one of the factors enabling the industrial revolution was a large swelling of the British industrial work force because improving farm labor productivity meant that fewer farm workers could feed more people. And it neglects a third crucial factor, the transportation revolution. And it risks focusing on technology when institutional changes played a crucial role. All of which I hope to explore and to discuss with my readers.
Meanwhile, for now I leave you with the following fascinating looks at London and Beijing early in the 20th century. See if you can spot a difference between the two societies which I find crucial. Indeed it is visually obvious and is implicit in a theme of the Chinese documentary. The internal combustion engines are irrelevant for our pre-20th-century purposes. Escape from the Malthusian trap was well underway by the early 19th century and the difference I have in mind had existed to some extent at least for many centuries. But if you're into more trivial pursuits see if you can spot the two "horseless carriages" on the London streets.
London in the 1900s:
Beijing and some other Chinese locales in the 1920s: