When Thomas Malthus published his famous essay “On the Principle of Population” in 1798, Alexander von Humboldt was 29 years old and had not yet embarked on the explorations that would later earn him the epithet “Father of Ecology.” Malthus’essay proposed that whereas population growth was cyclical, agricultural productivity growth was arithmetic. This disparity inevitably set limits on population size through famine and its consequences – disease and violence. Historically, population growth was cyclical.
Author Charles Kenny never minimizes Malthus' influence on economic theory. Instead, he applies his own expertise in history and economics to reassess Malthus' ideas. [I]n the years that preceded his analysis, history broadly lined up with the facts: populations rose or declined as circumstances changed, but the average person planet-wide consumed so little that they lived considerably below the poverty line of today's poorest nations.”(p.5) (Historically, there was no “obesity problem”).
The 14th century provided the best example of Malthus' population cycle. “For perhaps the 1st and only time in Northern European history, the Malthusian constant of land availability threatened to become a major factor in determining death rates.” (p.41) Land availability, however, was only a proximal factor. The Black Death wiped out on the average 50% of Europe's urban population. Agricultural productivity declined because because of a labor decline and disruption of trade routes for food distribution. This is how Kenny transforms Malthus' population cycle into the plague cycle. In short he argues that population growth has repeatedly been flattened by disease.
His comprehensive narrative is bolstered by copious bibliographic footnotes. Disease decimated Athens in the fifth century, the Antonine Plague which swept through the Roman Empire during Marcus Aurelius' reign, and the Plague of 542CE which contributed to the collapse of the Byzantine Empire during Justinian's reign are described. Of special interest to me was his claim that Napoleon's army was defeated by disease. As it slogged through Poland's marshes it was already starving, and easily decimated by typhus, a bacterial affliction transmitted by fleas, lice and mites. Two thirds of Napoleon's fighting force was either killed or incapacitated before even encountering the Russian army and retreating in the face of the brutal Russian winter.
Kenny reveals other interesting facts about the history of combatting disease. Edward Jenner developed the smallpox vaccine around 1796. However, as early as 1549 the Chinese were practicing variolation – in effect infecting people with a weakened form of the virus (although they based the practice on guesswork and knew nothing of viruses or the body's defense mechanisms). In 1714 a Royal Society paper described a similar procedure practiced in the Ottoman Empire. The information filtered down to members of the British nobility through word of mouth from the wife of the British ambassador to the Ottoman court.
Even before vaccines, improved sanitation was an effective inhibitor of disease. Joseph Bazalgette is not exactly a household name. However, he is the engineer who planned and oversaw the London sewage system which deposited waste downstream rather than directly into the Thames which supplied drinking water to London. Of course, Parliament only authorized the money for this project in 1858 when they themselves could no longer endure the stench from the river, a problem that had festered for well over a decade.
Kenny optimistically points to 20th century successes against disease, despite our encounter with Covid-19. Medical research and improved sanitation are obvious health priorities. Global initiatives such as the World Health Organization and the Gates Foundation have disseminated technical expertise and supplies. All of this is true, but I question whether we have the will to utilize these instruments. The anti-vaxer movement is far more entrenched than he believes. He places much of the blame on misleading medical research such as Andrew Wakefield’s autism claims published in The Lancet. However, his remedy of legally mandating vaccinations is a non-starter, at least in the libertarian climate of the United States. We are not far removed from the late Victorians he cites, who complained about the “despotic” medical profession.
He chides the “neo-Malthusians” concerned with the carrying capacity of the planet.” (p.235) I would argue that the “neo-Malthusian” view focuses on sustainability, rather than merely carrying capacity. Sustainability requires an understanding that resources are finite. Sustainability requires a candid assessment of long-term costs weighed against short-term profit. Carrying capacity should be a matter of concern. The solutions we have chosen – factory farming, deforestation, and environmental pollution are not sustainable. For Malthus the world was defined by urban and rural spheres. Alexander von Humboldt, whom I opened this review with, understood that the world was linked by interconnected spheres which included ecosystems that included but were not limited to humans.