Feb 132018

Today is the birthday (1766) of Thomas Robert Malthus FRS, an English clergyman and scholar who was hugely influential in political economy and demography. Normally I would not post about two famous Englishmen in related fields, back to back like this; I like my posts to have some variety. In this case, however, having Darwin Day yesterday, on Darwin’s birthday, followed by Malthus today, almost works, and the two belong together. Darwin would probably never have come up with the idea of natural selection if he had not been reading and considering Malthus on population when he was sailing in the Beagle and considering the reasons for all the variety that he saw. It would have been better for me if they had shared a birthday, and I could have united them in a post that way. A day’s difference is a small inconvenience. I cannot always conjure up coincidences.

In An Essay on the Principle of Population (1798), Malthus observed that an increase in a nation’s food production improved the well-being of the populace, but the improvement was temporary because it led to population growth, which in turn restored the original per capita production level. That is, humans had a propensity to exploit abundance for population growth rather than for maintaining a high standard of living. This position has become known as the “Malthusian trap.” He added that populations had a tendency to grow until the lower class suffered hardship and want and greater susceptibility to famine and disease, a view that is sometimes referred to as a “Malthusian catastrophe.” Malthus wrote in opposition to the popular view in 18th-century Europe that saw society as improving and in principle as perfectible. He saw population growth as being inevitable whenever conditions improved, thereby precluding real progress towards a utopian society: “The power of population is indefinitely greater than the power in the earth to produce subsistence for man”. As an Anglican cleric, Malthus saw this situation as divinely imposed to teach virtuous behavior. He remains a much-debated writer. Some economists contend that since the industrial revolution, humans have broken out of the trap. Others argue that the continuation of extreme poverty indicates that the Malthusian trap continues to operate. Others further argue that due to lack of food availability coupled with excessive pollution, developing countries show more evidence of the trap.

According to Malthus the propensity for population increase also leads to a natural cycle of abundance and shortages:

We will suppose the means of subsistence in any country just equal to the easy support of its inhabitants. The constant effort towards population…increases the number of people before the means of subsistence are increased. The food therefore which before supported seven millions, must now be divided among seven millions and a half or eight millions. The poor consequently must live much worse, and many of them be reduced to severe distress. The number of labourers also being above the proportion of the work in the market, the price of labour must tend toward a decrease; while the price of provisions would at the same time tend to rise. The labourer therefore must work harder to earn the same as he did before. During this season of distress, the discouragements to marriage, and the difficulty of rearing a family are so great, that population is at a stand. In the mean time the cheapness of labour, the plenty of labourers, and the necessity of an increased industry amongst them, encourage cultivators to employ more labour upon their land; to turn up fresh soil, and to manure and improve more completely what is already in tillage; till ultimately the means of subsistence become in the same proportion to the population as at the period from which we set out. The situation of the labourer being then again tolerably comfortable, the restraints to population are in some degree loosened; and the same retrograde and progressive movements with respect to happiness are repeated.

Malthus has faced opposition from economists both during his lifetime and since. One of his most vocal critics several decades later was Friedrich Engels.

Research indicates that technological superiority and higher land productivity had significant positive effects on population density but insignificant effects on the standard of living during the time period 1–1500 AD.] In addition, scholars have reported on the lack of a significant trend of wages in various places over the world for very long stretches of time. In Babylonia during the period 1800 to 1600 BCE, for example, the daily wage for a common laborer was enough to buy about 15 pounds of wheat. In Classical Athens in about 328 BCE, the corresponding wage could buy about 24 pounds of wheat. In England in 1800 CE the wage was about 13 pounds of wheat. In spite of the technological developments across these societies, the daily wage hardly varied. In Britain between 1200 and 1800, only relatively minor fluctuations from the mean (less than a factor of two) in real wages occurred. Following depopulation by the Black Death and other epidemics, real income in Britain peaked around 1450–1500 and began declining until the British Agricultural Revolution. Historian Walter Scheidel posits that waves of plague following the initial outbreak of the Black Death throughout Europe had a leveling effect that changed the ratio of land to labor, reducing the value of the former while boosting that of the latter, which lowered economic inequality by making employers and landowners less well off while improving the economic prospects and living standards of workers. He notes that “the observed improvement in living standards of the laboring population was rooted in the suffering and premature death of tens of millions over the course of several generations.” This leveling effect was reversed by a “demographic recovery that resulted in renewed population pressure.”

Robert Fogel published a study of lifespans and nutrition from about a century before Malthus to the 19th century that examined European birth and death records, military and other records of height and weight that found significant stunted height and low body weight indicative of chronic hunger and malnutrition. He also found short lifespans that he attributed to chronic malnourishment which left people susceptible to disease. Lifespans, height and weight began to steadily increase in the UK and France after 1750. Fogel’s findings are consistent with estimates of available food supply.

The rapid increase in the global population of the past century exemplifies Malthus’ predicted population patterns, whereby expansion of food supply has encouraged population growth. “Neo-Malthusianism” may be used as a label for those who are concerned that human overpopulation may increase resource depletion or environmental degradation to a degree that is not sustainable.

A strict Malthusian approach is depressing, but it fails to take into account factors that could undermine natural processes. Humans, for example, can decide en masse to limit family size, or it can be limited by the government. This is the reason that Engels was opposed to Malthus. If you take human agency out of the equation, then there is no chance to escape the Malthusian trap. Some people argue that the Industrial Revolution caused sustained economic growth that led to a “breakout” from the Malthusian trap and is known as “unified growth theory.” It is hard to tell at the moment because the 20th century saw monumental changes in technology, 2 world wars, massive genocide campaigns across the globe, easily available birth control, and a host of other factors that radically shift a purely Malthusian outlook.

For centuries, including in Malthus’ time bread was the “staff of life.” Without bread people starved to death, as we know from the famous saying falsely attributed to Marie Antoinette. This video walks you through bread making in the 18th century using a variety of grains that were substituted for wheat when there were shortages: