Escaping The Malthusian Trap

The start of industrialization in the late 18th century led to the first period of sustained economic growth in the history of humanity. Since then, there have been numerous predictions that resource scarcity would crash the party.

The first notable expert who predicted that resource scarcity would lead to inevitable disaster was the English cleric and economist Thomas Malthus (1766-1834). In his influential 1798 work An Essay on the Principle of Population, Malthus argued that the progress that was starting to occur in his own time would not last. According to Malthus, human population grows at an exponential rate because the “passion between the sexes” remains constant through time.

Malthus believed that the agricultural output could not keep up with the exponential growth in human population. Inevitably, famine would result, standards of living fall, and wars over scarce resources ensue.

After famines and wars kill off a significant number of people, the population falls to a level where there is enough food available to feed everyone adequately. In this period, there are fewer wars over scarce resources, people continue to have many children, the population expands, and the cycle continues all over again. This cyclical phenomenon is called the Malthusian Trap. Malthus believed that humanity would forever be trapped in this unfortunate cycle.

Malthus’s theories were actually a remarkably good representation of history up to his own day. Economic historians have referred to the period before the industrial revolution as the “Malthusian Epoch.” In the time since Malthus wrote his treatise to the present, however, his predictions have been remarkably wrong.

Worldwide human population has increased from around 800 million in 1800 to over 7 Billion in 2016. In Western Europe, food consumed per capita has continued to expand from under 2,000 kilocalories per day in 1800 to well over 3,000 kilocalories per day in 2016. An order of magnitude more humans now are healthier, wealthier, and eat better than at any time in human history. How did this happen?

Two of Malthus’s assumptions have not panned out over the last two centuries:

  1. Malthus assumed that there was a limit to the ability of agriculture to provide subsistence for a growing population. In reality, since 1800, farm mechanization and better fertilizer usage have increased the output per farmer on the order of 400x in developed countries.
  1. Malthus assumed that population would continue to grow at an exponential rate until limited by a resource crisis. In reality, over the last 200 years, a phenomenon called the demographic transition has occurred: as people lived longer and became healthier and wealthier, they voluntarily decided to have fewer children. Now, population growth rates are negative in some countries including Japan and much of Europe. World population growth peaked at 2.1% in the 1960s. Now, the world population growth rate is down to 1.2% and dropping. Demographers predict that the earth’s population will continue to grow, but at a decreasing rate. Barring some catastrophe, world population is likely to plateau at 9.5-12 billion in the year 2100.

This raises the question of whether the earth can support that many people with increasingly higher standards of living. It is possible that Malthus’s predictions of scarcity will ultimately be vindicated, even if he was off on the timing – that is the essential argument of Stanford University biologist Paul Ehrlich’s (in)famous 1968 book The Population Bomb. Ehrlich believed that Malthus was correct in principle, just off in timing. As Paul Ehrlich says in the first sentence of the book: “The battle to feed humanity is over. In the 1970s and 1980s hundreds of millions of people will starve to death…”

The last fifty years have demonstrated that The Population Bomb was also, at the very least, off in timing. Like Malthus, Ehrlich underestimated the effect of the demographic transition and failed to anticipate the massive expansion of global agricultural output in the Green Revolution.

Whether Malthus continues to be proven wrong will largely depend on whether technological innovation continues to create new ways to meet the growing demand for resources.


Image courtesy of Flickr. Originally published by S&S on November 8, 2016.


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