The Human Journey
Guns, Germs, and Steel

Turning Points in the Development of Contemporary Society

Guns, Germs, and Steel:

The Fates of Human Societies

W. W. Norton & Co, 1997

Available for purchase here

About the Author: Jared Diamond is a professor of physiology at UCLA School of Medicine. He is a recipient of a MacArthur Foundation Fellowship and was awarded a 1999 National Medal of Science. He is also the author of The Third Chimpanzee and Collapse.
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Why has Eurasian culture been able to conquer and to dominate the rest of the world? The author attempts to answer this question and scientifically prove that “History followed different courses for different peoples because of differences among peoples’ environments, not because of differences among peoples themselves.” He uses information from genetics, molecular biology, biogeography, behavioral ecology, epidemiology, linguistics, archeology, and history in his discussion to establish this, and to support the claim that Eurasians had geographical and ecological advantages that gave them a head start on the rest of the world.

Environment Really Matters

Map of Polynesia

The early history of the Polynesians in the Pacific shows how environment determines the path of societies.

Between 1200 BC and 500 AD these people scattered over thousands of Pacific islands. They settled on islands that vary widely as to climate, geology, marine resources, area, fragmentation, and isolation. The cultural package taken with the emigrants was the same in all cases, but what they could retain of it was determined by the environment in which they settled. Those who settled on large, fertile, tropical islands with good sources of fresh water retained the entire package. In the least welcoming locations the people reverted to hunting and gathering. In isolated locations, if animals died out replacements could not be obtained. Islands with a combination of high mountains might develop several communities with little contact with each other. Those with low topography tended to have few sources of fresh water and agriculture was less productive. Coral atolls and limestone islands tended to have poor soil; volcanic islands to be fertile. Cultural complexity varied with population density.


There are no differences in intelligence and adaptability between the people who took up farming and those who remained hunter-gatherers.

A look at locations such as the Eastern United States or New Guinea quickly proves the point. Hunter-gathers had to know the names and uses for all locally available plants and animals. When exposed to a new environment, they quickly assessed and gathered promising species. When more productive plants were introduced, such as corn, beans, and squash in the Eastern United States, they were quickly adopted and populations and social complexity grew.

The acquisition of food production was a prerequisite to Eurasian superiority

What caused hunter gatherers to begin growing their food remains unsettled, but the following five reasons seem agreed on.

Barley Farm
Barley farm
  • Decline in the availability of wild food.
  • Increase in availability of wild candidates for domestication (e.g. climate changes that increased the spread of cereals). One or two crops are not enough for hunter-gatherers to change their life style.
  • Abundant wild cereal harvests led to development of technologies used for collecting, processing, and storing food.
  • Reciprocal links between increases in population and increases in food production.
  • The denser populations of food producers allowed them to displace or kill hunter-gatherers.

What characteristics of plants and animals favor domestication?

Plants which were already edible and plentiful in the wild and needing few mutations to adapt to farming were the earliest. The plant needs to be easily and quickly grown from seed, produced in large quantities, and have a high caloric value. They need to be suitable for storage, i.e. able to survive a long dry season and resume growing rapidly when the rains return.

Animal candidates for domestication all share the same set of characteristics. This explains why almost all the successful domestications were Eurasian. Although many small mammals and birds have been domesticated around the world, only 14 species of big (over 100 pounds) mammals were domesticated before the 20th century. Of these, all but one (llama/alpaca) is native to Eurasia. There were no cultural obstacles to domestication in other locations. We know this because of the rapid acceptance of Eurasian domesticates wherever they were introduced. However, lacking even one of the characteristics necessary for domestication of an animal disqualified the candidate.
These were:

  • They had to convert fodder to human food efficiently.
  • They had to breed in captivity and mature quickly.
  • They had to live in herds with a well developed dominance hierarchy so that humans could replace the dominant herd leader.
  • The animals had to have a pleasant and docile disposition and be able to be kept in large groups.

Territorial animals cannot be penned together or they will fight. Cats and ferrets were the only territorial animals domesticated and they were never used for food.

Domesticated animals

The Fertile Crescent

Western Eurasia, also called the Fertile Crescent, was an early center of the domestication of plants. 6 of the 12 major crops of the world originated there. It had a Mediterranean climate with mild wet winters and long hot dry summers. Why didn’t other locations with a Mediterranean climate, California, Chile, SW Australia, and South Africa, develop indigenous agriculture?

Western Eurasia had a number of advantages. Its large size and more variable climate meant a larger diversity of wild plants and animals. Over half of the largest seeded grasses originated in the Fertile Crescent. Chile had only two strains, California and South Africa one each, SW Australia had none at all. Opportunities for hunter-gatherers in the area were limited. The wide range of altitude and topography allowed for staggered harvest seasons. Four species of large mammals suitable for domestication were native to the area, none were found in the other Mediterranean areas. Very early, people in the Fertile Crescent had a potent and balanced package for intensive food production. They had cereals for carbohydrates, legumes for protein, flax for cloth and oil, and large domestic animals for food, plowing, and transportation. In contrast, Mesoamerica had only two small domestic animals (the turkey and dog), and their corn was difficult and slow to develop. Other locations had even more limited options.

Eurasia had a geographical advantage: The major axis is east-west

Fertile Crescent map
The Fertile Crescent (NASA map by Robert Simmons)

North and South America are on a north-south axis, as is Africa. There were also fewer geographical barriers to slow dispersion.

An east-west axis means that adjoining areas are in similar latitudes and so have similar seasons and climates. This had huge consequences for the spread of food production and domestic animals. Fertile Crescent crops grow well in temperate zones and were able to move rapidly east and west to Europe, Egypt, North Africa, Ethiopia, Central Asia and the Indus Valley. Likewise crops spread east and south from China to Southeast Asia, the Philippines, Indonesia, Polynesia, Korea, and Japan. The AmericasIn the Americas,the deserts of the Southwestern United States delayed the spread of Mesoamerican crops to the Eastern parts of the continent. Likewise, the tropical lowlands of Central America restricted the movement of crops and animals between the Mexican and Andean highlands. In Africa, the 2000 miles of tropical conditions south of the Sahara prevented the crops suitable for Mediterranean climates from reaching South Africa and slowed the movement of crops from the Sahel and West Africa to East and South Africa. Climactic differences (summer rather than winter rains) prevented crops which grew in the Indus valley from spreading east.

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