Book Summary: “Plagues and Peoples” by William McNeill

Plagues and Peoples

Title: Plagues and Peoples
Author: William McNeill
Scope: 4 stars
Readability: 4 stars
My personal rating: 5 stars
See more on my book rating system.

If you enjoy this summary, please support the author by buying the book.

Topic of Book

The author explores the impact of disease on human history.

My Comments

With all the current focus on the COVID-19 (coronavirus), I thought that it would be a good time to post a summary of this classic book about the role of disease in human history. Some people are terrified by the topic, but I feel a certain comfort in knowing that previous generations with much simpler technology have survived far worse.

Key Take-aways

  • Viruses, bacteria and parasites have played an important role in human history over the last 10,000 years.
  • Though dangerous, these critters are not trying to harm us. They are usually just looking for a nice home. Unfortunately, that home is inside us.
  • The movement of people around the globe and mixing with animals promote an environment where new viruses, bacteria and parasites evolve.
  • When a new species evolves or moves into a new area, it confronts humans with varying degrees of health and immunity.
  • Over generations, humans, viruses, bacteria and parasites evolve so they can co-exist.
  • Humans have survived far worse than what we are confronted with today.

Important Quotes from Book

“One can properly think of most human lives as caught in a precarious equilibrium between the microparasitism of disease organisms and the macroparasitism of large-bodied predators, chief among which have been other human beings.”

“The farther human populations penetrated into cold and/or dry climates, the more directly their survival depended on their ecological relations with large-bodied plants and animals. Balances with minute parasitic organisms, so important in the tropics, became comparatively insignificant.” (p63)

“Food production permitted a vast and rapid increase in the number of people, and soon sustained the rise of cities and civilizations. Human populations, once concentrated in such large communities, offered potential disease organisms a rich and accessible food supply that was quite as unusual, in its way, as the big game of the African savanna had been for out remoter ancestors.” (p66)

“But irrigation farming, especially in relatively warm climates, came near to recreating the favorable conditions for the transmission of disease parasites that prevailed in tropical rain forests where humanity’s remote ancestors had presumably emerged.” (p79)

“Domesticated animals were already chronic bearers of viral and bacterial infections… Constituting large populations of a single species, they provided exactly the condition required to allow bacterial and viral infection to become endemic” (p96)

“The entire process of adjustment between host and parasite may be conceived as a series of wavelike disturbances to preexisting biological equilibria. The initial disturbance is likely to be drastic… a fluctuating balance then asserts itself, with periods of unusual frequency of infection alternating with periods when disease wanes and may almost disappear.” (99-100)

“When civilized societies learned to live with the “childhood diseases” that can only persist among large human populations, they acquired a very potent biological weapon. It came into play whenever new contacts with previously isolated, smaller human groups occurred.” (p113)

“Observed from the civilized side of the frontier, an initial die-off and disruption of local social defenses opened the way for an overabundant civilized peasantry to move onto new ground and there find chance to thrive. For the most part this phenomenon remained sporadic and local.” (p116)

“it seems sure that the major civilized regions of the Old World each developed its own peculiar mix of infections, person-to-person diseases between the time when cities first arose and about 500 BC.” (p122)

“As compared to China, however, both the political and intellectual structures that arose in the Ganges region before and after 500 BC remained unstable, and never were consolidated into an enduring whole. One of the reasons – and perhaps a very pervasive factor in all Indian history – was the heave microparasitism characteristic of a climate as warm and wet as that of the Ganges Valley and the rest of India’s best agricultural land.” (p 142-3)

“it appears that Mediterranean coastlands offered a relatively disease-free environment into which populations could and did expand.” (p153)

Epidemic in Athens in 430-429BC lead to its defeat by Sparta, and it never entirely recovered. (p160-1)

“When travel across the breadth of the Old World from China and India to the Mediterranean became regularly organized on a routine basis, so that thousands of individuals began to make a living by traveling to and fro, both on shipboard and by caravan, then conditions for diffusion of infections among separate civilizations of the Old World altered profoundly…  It is my contention that something approximating this condition did in fact occur, beginning in the first century AD.” (p165-6)

Epidemic in Roman Empire in 165 AD killed “as much as a quarter to a third of the entire population… What mattered even more was the fact that this episode inaugurated a process of continued decay of the population of Mediterranean lands that lasted, despite some local recoveries, for more than half a millennium.” (p174-5)

Muslim defeat of Byzantines in 634 was partly caused by repeated plagues from 542 onward. (p189)

Mongol wars and plagues caused a crash in population in China from 123 million in 1200 to 65 million in 1393 when Mongols were expelled. (p235)

Plague in Mongolia probably contributed to their retreat after 1346. By 1550 agricultural pioneers began to penetrate the western steppe (p274)

“It was not really until after 1850 or so that the practice of medicine and the organization of medical services began to make large-scale differences in human survival rates and population growth.” (p336)

“By 1900… the world’s urban populations became capable of maintaining themselves and even increasing in numbers without depending on in-migration from the countryside” (p381-2)

“The sudden lifting of the malarial burden brought about by the liberal use of DDT in the years immediately after World War II was one of the most dramatic and abrupt health changes ever experienced by humankind.” (p391)

“Decisive breakthroughs in military medical administration came just after the turn of the twentieth century. Until then, in even the best-managed armies, disease was always a far more lethal factor than enemy action, even during active campaigns.” (p393)

If you would like to learn more about history, read my book From Poverty to Progress.

One comment

  1. The entire summary is informative.I found this particular line a little humorous, “Though dangerous, these critters are not trying to harm us. They are usually just looking for a nice home. Unfortunately, that home is inside us.”


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