The Book in Three Sentences

Some environments provide more starting materials and more favorable conditions for utilizing inventions and building societies than other environments. This is particularly notable in the rise of European peoples, which occurred because of environmental differences and not because of biological differences in the people themselves. There are four primary reasons Europeans rose to power and conquered the natives of North and South America, and not the other way around: 1) the continental differences in the plants and animals available for domestication, which led to more food and larger populations in Europe and Asia, 2) the rate of diffusion of agriculture, technology and innovation due to the geographic orientation of Europe and Asia (east-west) compared to the Americas (north-south), 3) the ease of intercontinental diffusion between Europe, Asia, and Africa, and 4) the differences in continental size, which led to differences in total population size and technology diffusion.

Guns, Germs, and Steel summary

This is my book summary of Guns, Germs, and Steel by Jared Diamond. My notes are informal and often contain quotes from the book as well as my own thoughts. This summary also includes key lessons and important passages from the book.

  • History followed different courses for different peoples because of differences in their environments not because of biological differences in the people themselves.
  • This book seeks to answer the question, “Why did the rate of progress differ so much for cultures on different continents?”
  • Around 11,000 years ago all human societies were hunter gatherers.
  • Understanding the causes of history improves our ability to intervene and improve the world. Many people mistakenly assume that discussing history is just a way to explain away tough issues. Not at all. It improves our ability to take effective action.
  • The most common explanation of the different trajectories experienced by Europe compared to Africa, Asia, Oceania, etc. is genetic and biological. People assume there is some innate biological difference that made Europeans smarter, more creative, or more resilient. Science, however, has produced no substantial evidence to indicate this is the primary cause of different outcomes.
  • Interesting side note: scientists are always competing to discover the “earliest human remains” or the earliest XYZ. As a result, every few years there is a new “earliest” discovery. Only one can actually be the earliest, of course.
  • The occupation of Australia was an incredible feat. It was the first use of water craft and range extension by humans.
  • Humans were likely responsible for the extinction of nearly all of Australia’s large mammals. The same is true for many large mammals that occupied the Americas over 10,000 years ago.
  • The environment of ancient Polynesian society heavily dictated the lifestyle and behaviors. The many islands have widely varying landscapes and climates. Whether or not cultures developed weapons and became skilled at warfare, whether they became hunter gatherers or farmers, whether they acted more tribal or more hierarchical was largely determined by the environment in which these people lived.
  • Food and animal domestication arose independently in five different areas of the world (at widely differing times) and possibly four others although there is still some contention about those.
  • We often think there is a clear division between farmer and hunter gatherer lifestyles, but actually there can be a blending of the two. For example, some cultures plant crops, resume a hunter gatherer lifestyle while they grow, then return to harvest and eat.
  • Agriculture did not lead to an unequivocally better lifestyle. In fact, for those who actually grow food life tends to be worse than it would be as a hunter gatherer. If this is true, and the evidence seems to point that way, then it means that advancement of civilization has essentially happened on the backs of society’s have-nots. In other words, the entire system we live within – agriculture, capitalism, etc. – requires inequality to function.
  • Agriculture allowed food production per unit area to increase, which meant a given area could support a larger population. This allowed farming cultures to defeat hunter gatherer cultures by sheer force due to larger populations. This, in turn, led to the spread of more agricultural societies across the globe.
  • Throughout the industrial revolution in Great Britain, moths of darker colors became more likely to survive because the surrounding environment become dirtier and covered in soot, smoke, and debris. Thus, it was more likely that dark-colored moths would survive than light-colored moths. As the environment changed, so did the evolution of moths. A fascinating example of evolution on a small scale.
  • Cereal crops alone account for more than half of the food consumed by modern humans.
  • The rise of indigenous food production in certain areas was the result of a few factors. First, certain areas had plants better suited to domestication. This led people to domestic earlier in those regions. Second, because of this early start, these people eventually domesticated more difficult plants. Evidence seems to indicate that all people’s are capable of food production and even modern hunter gatherers seem to be naturally moving that way.
  • The rise of agriculture in some areas before others has to do with the environment, not the intelligence of the people.
  • The Anna Karenina Principle: In many areas of life, success is not about doing one thing correctly, but about avoiding many possible modes of failure.
  • Domesticated animals differ in multiple ways from their wild ancestors. For example, many domesticated animals are different sizes and have smaller brains than their wild ancestors.
  • Domestication of large mammals ended approximately 4500 years ago. This indicates humans attempted to domesticate all of them and no suitable species remained. This is another piece of evidence that the type of animals available dictated the domestication in certain regions, not the people living in the region. This the spread of agriculture was once again impacted by the environment.
  • There is a inefficiency during the eating process. The nutrient transfer is much less than 100 percent and typically around 10 percent. For example, it takes 10,000 pounds of corn to create a 1,000 pound bull.
  • The primary geographic axis of North and South America is north-south. That is, the land mass is more longitudinal than latitudinal. The same for Africa. But for Europe and Asia, the primary axis is east-west. Interestingly, this positioning and shape matters greatly because it appears that agriculture and innovations spread more rapidly along east-west axes than along north-south axes.
  • Locations along the same east-west axis share similar latitudes and thus have similar day lengths, seasons, climate, rainfalls, and biomes. All of which increase the speed of innovation relative to north-south axes.
  • All tropical rainforests are within 10 degrees of latitude of the equator.
  • One collection of evidence for the difference in spread along geographic axes is the spread of domesticated crops. Many crops spread across Asia with one domestication, while crops like cotton or squash were domesticated in multiple individual areas throughout Mesoamerica. This is because the crop spread too slowly for one domestication to takeover the region.
  • It is vital to realize that although Diamond is discussing long time frames of hundreds or thousands of years, the core idea can be applied to short time spans of individual behavior as well. Indeed, large long term differences only occur because short term differences are repeated over and over again. Small environmental differences led to small changes in individual behavior, which resulted in significant differences when repeated for thousands of years.
  • One reason farming communities developed immunity to diseases that wiped out hunter gatherer populations is that some diseases (like measles) are “crowd diseases.” They require a large population to sustain themselves because they act quickly: you either die or develop immunity. In order for the disease to sustain itself there must be enough new babies born to contract the disease from those who have already developed immunity. Only agricultural communities could grow to the required population size.
  • On average, farming sustains populations that are 10x to 100x larger than hunting and gathering.
  • North America was populated by about 20 million Native Americans when Columbus landed in 1492. Within two centuries, 95 percent of the native population had died, most of them from infectious diseases.
  • Writing systems are historically seen as the deciding factor on whether an ancients civilization is considered advanced or not. This can be debated. The Incas built a great civilization without writing.
  • All alphabets in the modern world evolved from one original alphabet, either in idea or actual written form, developed in the Middle East.
  • Writing evolved independently in a few areas, but was spread via idea diffusion in most cultures and locations.
  • Most inventions are not a result of necessity, but rather the result of tinkers and curiosity.
  • Technology develops cumulatively rather than in isolated heroic acts. Even people we often associate with acts of genius like the Wright Brothers and Thomas Edison actually built upon the work of predecessors and had capable people who followed them and advanced ideas.
  • Technology finds most of its uses after it has been invented rather than being invented to solve a foreseen need. The phrase, “necessity is the mother of invention” is generally incorrect. (Even though some examples, like the Manhattan Project, exist.)
  • Long life expectancy is one reason technology might develop and spread faster in some locations rather than others. A longer life increases the surface area you have to test ideas and allows you to take on longer projects that you might otherwise avoid with limited time.
  • Geographic location is a key determinant in the pace of technological innovation and acceleration because a centrally located society will not only accumulate knowledge and technology from their own inventions, but also from neighboring societies. In the case of a particularly large land mass like Eurasia, technologies can spread from one culture to another and continue to do so along the entire span of the continent. This spread occurs much more quickly in these locations than it would to, say, aboriginal cultures in Tasmania, which did not receive outside contact from other civilizations for over 10,000 years.
  • Government and religion are two of the main reasons some societies overcame others. These shared myths led to collaboration and increased power.
  • There are four levels of organization in society: bands (5-80 people), tribes (100-1000 people),  chiefdoms (1000 to tens of thousands of people), and states (50,000 or more people).
  • Humanity has been on a clear path from small groups to larger ones, culminating in states, over the last few thousand years.
  • The size of a population in a region is a strong predictor of the complexity of the society.
  • Culture is heavily dependent on population density. The higher the population, the more culture seems to spawn and spread.
  • War, or the threat of war, is the primary factor in the amalgamation of human societies throughout history. It is how cultures merge.
  • Five dog night is an Australian phrase referring to a very cold night because you would need to use five dogs as blankets.
  • Isolation is a key factor preventing creativity and innovation from spreading because most people and societies get their ideas from outside societies. So constant connection to others and trading of ideas and resources is essential for technological and creative progress.
  • Food production was a key component in the determining the strength of a society. People sharing similar ancestors inhabited New Guinea and Indonesia, but the Indonesians were still hunter gatherers while the New Guineans had develop agriculture. When Austronesians invaded the region, Indonesians fell under their control, but New Guineas (with their food, germ resistance, and technologies) were able to resist.
  • Again and again, the environment dictated the spread of power throughout islands of East Asia and the Pacific. Depending on location, islanders differed in their connectedness to other peoples and in the plants and animals available to them to domesticate. People with favorable locations for food production and access to technology replaced those with less favorable environments.
  • The end of Chapter 18 shares multiple interesting examples of peoples who were largely similar genetically because of similar ancestors, but developed very different societies and technologies due to the their individual environments.
  • Example of cultural evolution: the Moari of New Zealand were able to determine the most useful rocks and animals for domestication within a century of arriving.
  • The striking differences in the histories of peoples on different continents have been due not to differences among the peoples themselves, but to differences in their environments.
  • There are four primary reasons Europeans rose to power and conquered the natives of North and South America, and not the other way around.
  • Reason 1: Continental differences in the plants and animals available for domestication. The differences are vast. Europe and Asia had the best prospects, then Africa, then the Americas, then Australia. The improved agricultural aspects led to larger populations and larger armies in Europe and Asia.
  • Reason 2: the rate of diffusion of technological innovation due to the orientation of continents (east-west vs. north-south) and geographic barriers (mountains, deserts, etc.). The favorable geography of the Europe and Asia landmass resulted in much faster agricultural and technological expansion.
  • Reason 3: ease of intercontinental diffusion. It was easy for ideas, technologies, and innovations to spread between Europe, Asia, and Africa. However, it was quite difficult for things to spread to the Americas because of large oceans and the only close landmass being in cold climates and at high latitudes unsuitable for farming.
  • Reason 4: continental differences in total population size. Europe and Asia had a huge landmass where there was constant and widespread competition.
  • All human societies contain inventive people. It’s just that some environments provide more starting materials and more favorable conditions for utilizing inventions than other environments.
  • The fragmentation of Europe was a key in enabling Columbus to cross the Atlantic. He was turned down by four different kingdoms before finally convincing the king and queen of Spain to fund his trip. Meanwhile, Chona had the technology to explore the world by ship, but their dictator at the time did not want to do so. In this way, one person prevented an entire made of people (with the technology) from succeeding. A little fragmentation is good. Too much centralized power means one person can handcuff the creativity of many.
  • In the 1960s and 1970s, the decisions of a few Chinese leaders resulted in the schools closing in the country for five years. Crazy how so much centralized power is still playing a huge role.
  • Europe has always been far more fragmented than China. Even at its peak, the Roman Empire never controlled more than half of Europe.
  • Understanding ultimate causes is essential to understanding human behavior.
  • Prediction of history is much easier over long time spans, but basically impossible over short time spans.
  • Great discussion of science in the last half of the epilogue.
  • Careful observations of natural experiments (things happening in the real world) can lead to fascinating and useful insights.
  • Epidemiology, ecology, and evolutionary biology are developing better methods for dealing with the confounding factors often present in natural experiments.

Reading Suggestions

This is a list of authors, books, and concepts mentioned in Guns, Germs, and Steel, which might be useful for future reading.

  • Toynbee’s 12-volume series on history
  • Film: The Gods Must Be Crazy
  • Maori New Zealand’s musket wars
  • Applications of Chaos Theory. The QWERTY keyboard vs. Dvorak keyboard is one example.

Additional Thoughts

This is a list of interesting notes, side stories, or additional thoughts that were sparked as a I read the book.

  • Many large mammals used for food production were not domesticated in the Americas because they became extinct around 13,000 BC (due to the appearance of humans?). This was well before agriculture arrived in America, thus domesticating these animals never occurred to prehistoric hunter gatherers. But why?

Guns, Germs, and Steel by Jared Diamond

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