Guns, Germs, and Steel

Guns, Germs, and Steel Summary and Analysis of Part 2: The Rise and Spread of Food Production


In Part 2, Diamond picks up with the question that ended Part 1: What gave the Spanish such an advantage over the Incas? The Spanish technology that allowed Pizarro to defeat Atahuallpa would have been impossible without agricultural advancements that began almost 1,000 years before that event. Agriculture and controlled farming were more efficient than hunting and gathering, so there was time for specialization to develop. Farming allowed social stratification to develop, with many peasants working for a small group that owned land. These owners were then freed up to develop new technologies and skills because they no longer had to spend all their days hunting for food. Populations grew as more people could be fed. While societies developed agriculture, they also began to domesticate certain large mammals. Thus, these societies had the technology, energy, and time to go to war against other nations. They also were the first to catch infectious diseases like smallpox, measles, and flu from these animals, which allowed them to evolve resistance to these diseases. In short, agriculture and domestication led to dense populations and societies that were settled, politically centralized, technologically innovative, and economically complex. Food production was a prerequisite for the conquest of other societies.

Ironically however, the areas of the world that had the best climate for agriculture were not the ones to invent agriculture. Mesopotamia was among the first places where agriculture could be found, even though it was a dry environment. In America and Australia, agriculture appeared most likely when foreign invaders came and was probably introduced through a single plant that was farmed. In this way, agriculture spread from its origins in Mesopotamia, through to most other parts of the world. It is more difficult to explain why food production failed to appear until modern times in some areas that should have been very suitable for it, such as the West Coast of America. On the other hand, it did appear in some areas that seem marginal and unfertile at first glance. Only a few areas of the world were able to develop food production independently, and did so at very different points in time. Those who had a head start on food production also had a head start on developing guns, germs, and steel. This distinction between areas that developed early food production and areas where people remained hunter-gatherers separated the “have and have-nots.”

All societies began as hunter-gatherer, so the eventual discrepancies between human societies did not exist from the beginning. Actually, being a hunter-gatherer was not even necessarily less advantageous than being a peasant farmer; some farmers spend more hours per day on food production than hunter-gatherers do. Thus, in certain areas, people were exposed to farming but decided not to adopt it. Furthermore, some people became sedentary without adopting food production—sedantariness and food production were not necessarily linked. It is also important to note that food production was not “discovered,” nor “invented.” Instead, it evolved as a by-product of decisions that were made without full knowledge of what their consequences would be. In studying the rise of food production, then, Diamond considers why it evolved in some places at certain times, rather than in others. In fact, people began by both collecting and cultivating wild foods. They only began to increase cultivation and decrease collection when the crops they had available proved to be especially good for cultivation. The availability of such crops varied by region. Five major factors contributed to the relative advantage of cultivation in certain areas: declining availability of wild foods, increased availability of domesticable wild plants, the development of technologies that made food production easier, rising population density, and the increased military strength of food producers as compared to hunter-gatherers. Hunter-gatherers were able to resist the pressure to become food producers only in areas that were isolated and made the immigration of food producers or techniques very difficult. In most other areas, food production reigned as the superior strategy.

Why did certain wild plants make for especially good crops, while others didn’t? Part of the explanation lies in the obvuiys features of certain plants. For example, some plants have obviously superior features by which hunter-gatherers would choose them over other options: large size, tastiness, seedless fruits, and long fibers. Hunter-gatherers tended to harvest wild plants that had these desirable qualities, and thus unconsciously dispersed these favorable plants more than others. These plants slowly became more common, until they became domestic crops. These more useful plants were also affected by non-human factors: seeds being dispersed more easily, some seeds being saved for later so that a drought would not kill all plants at once, and self-reproduction that allowed beneficial mutations to spread more easily. Overall, both human and natural selection helped certain plants to survive and spread more than others. (Natural selection refers to the process of species evolving through random mutuations that allow them to survive and reproduce successfully.) These better-adapted plants were the ones that would later become crops. Some of these plants included barley, peas, and cereals that grew in the Fertile Crescent, an area in the mideast. The production of cereal, in particular, gave the Fertile Crescent a huge advantage because such crops grew fast, were high in carbohydrates, and yielded a lot of edible food per area cultivated; thus, they gave people in the Fertile Crescent a huge advantage by providing them with more plentiful and efficient food options. Areas that grew things like acorns had a disadvantage. Acorns, for example, are a very inefficient food source: oak trees take an extremely long time to grow, their seeds are spread by squirrels in a way that makes them impossible for humans to select and control, and they are much more bitter than other nuts like almonds. Thus, local environments had a huge impact on the rate of the development of food production. Areas that happened to have wild crops with a number of advantages that made them easier and more efficient to domesticate were the first to develop food production.

So why did agriculture not develop independently in areas that seemed fertile and suitable for these kinds of crops, like Europe and Australia? The explanation could lie either with local people being incompetent, or locally available wild plants having some kind of problem. Diamond shows that it is, in fact, the latter. There are very few major crops in the world. It has been thousands of years since humans have domesticated any new major crops. It is thus unsurprising that many areas of the world would happen to lack a naturally occurring major crop, and that local peoples would not be able to domesticate the less favorable ones they did have available. But it is harder to explain why certain plants were domesticated in one area and not in another. The answer to this involves the general environmental context of these areas where such plants failed to be domesticated. It is important to remember that plant domestication always had to compete with the hunter-gatherer lifestyle for convenience; if domestication was not significantly more efficient, then people would not adopt it. In areas that didn’t domesticate major crops, there were not enough other domesticable wild plants to justify the effort needed to domesticate the ones that were domesticated in other areas. For example, nomadic hunter-gatherers would not give up their traditional lifestyle and tend to apple orchards unless there were other plant and animal options that would make this sedentary existence competitive with the hunter-gathering existence. For agriculture to develop, an area had to have a number of easily domesticated major crops and animals. The entire suite of wild plants and animal species available to a given people is important to keep in mind when assessing why that population succeeded or failed to domesticate a particular plant.

The Fertile Crescent is a major and unusual example of this kind of area. It had five important advantages over other zones. First, it had the world’s largest zone of "Mediterranean" or temperate climate, which meant that it had a high diversity of wild plant and animal species and thus many different options for domestication. Second, it had the greatest climatic variation seasonally, which favored the evolution of many annual plants and contributed to the diversity of the region. Third, it had a wide range of altitudes in a short distance, which allowed people to stagger harvest seasons: after harvesting the first batch of crops in a low area, they could move higher to harvest seeds as they continued to mature. Fourth, it had many big wild mammals that could be domesticated. Mammals such as sheep, goats, and cows could help with the farming of plants as well. Fifth, it had less competition from the hunter-gatherer lifestyle because there were not many options for fishing or hunting animals for meat. All of these advantages lay with the natural environment of the Fertile Crescent, and not with the biology or culture of its people. People in the Fertile Crescent domesticated local plants much earlier thanks to the many environmental advantages available to them. Because of this, they domesticated more productive and valuable species, developed a denser human population more rapidly, and thus entered the modern world with more advanced technology, complex political organization, and epidemic diseases that would infect other populations.

Another important concept to keep in mind is that success actually requires avoiding many separate possible causes of failure. If even one necessary factor for success in domestication is missing, then domestication will fail overall. Potentially domesticable wild animals were also an important feature of a given environment, for example. Domestication of animals means transforming them into something more useful to humans. But very few species are actually suitable for domestication, while most efforts to domesticate animals have resulted in failure. There are six factors that contribute to successful domestication of a species: if it doesn’t have a picky diet, if it grows quickly, if it breeds well in captivity, if it has a naturally pleasant disposition, if it does not have a tendency to panic when trapped, and if it has a hierarchical social structure that allows it to adapt to humans as new “pack leaders.” This explains why horses are domesticable while zebras are not; while horses travel in herds and have a calmer disposition, zebras tend to be rebellious even when in captivity. Domestication of animals is actually very difficult, since the animal in question must meet all of these many conditions. Eurasian peoples happened to inhabit an area that naturally had more wild animals that were favorable to domestication. This was because Eurasia had a large area and ecological diversity that gave it many species, did not lose as many species in extinctions, and had more surviving candidates suitable for domestication than other continents did.

One of the most obvious and important environmental differences across continents is axis orientation. While the Americas span a larger distance from north-south than east-west, Eurasia’s major axis is east-west. This means that, in Eurasia, the climate is relatively similar across all areas of the continent. Localities at the same latitude have the same day length, seasonal variation, diseases, temperatures, and habitats. In the Americas, on the other hand, climate varies drastically from the north to the south. It was thus much easier for crops and livestock to spread on continents where the climate was similar all across the landmass. This was because the food and livestock first domesticated in the Fertile Crescent were already well adapted to the climate in other parts of Eurasia, and could quickly spread across the continent. Because food production contributed to denser populations and more potential for complex societies and technologies, this had an effect on the development of writing, technology, and empire as well. Eurasia’s early advantage is what helped it to more rapidly develop literacy, metallurgy, technology, and empire.


The first chapter of this section begins with another personal anecdote. Diamond recalls his time working for a farmer in the US, who also employed a Native American man named Levi. He remembers Levi cursing Europeans’ arrival in America, which subjected his people to great hardship. Diamond was personally struck by this outburst, which brought his attention to the ways in which native peoples continued to suffer from America’s long history of colonization. He continues to make use of personal anecdotes throughout the section in order to add color to the text. Diamond’s use of these examples helps to give his book the arc of a story; he is the narrator, who comes upon various scenarios that challenge him to take a closer look at his surroundings and consider how certain situations came to be in the first place. In this way, Diamond’s text guides the reader through his own personal journey, even as it provides a wealth of analytical, historical, and scientific evidence, as well. These more literary elements of the text—a plot, narrative voice, and moments of reflection—culminate in the metaphor with which Diamond ends the section: “Around those axes turned the fortunes of history.” This use of figurative language goes hand-in-hand with his continuous employment of literary flourishes throughout the text.

He also relates to his readers with anecdotes that don’t just chart his own journey, but also help a wide variety of potential relates engage with his subject. As he begins his chapter on the domestication of wild plants, he switches into the second person to introduce the topic: “If you’re a hiker whose appetite is jaded by farm-grown foods, it’s fun to try eating wild foods.” This statement helps him to relate the topic directly to readers who may have some experience with hiking. He goes out of his way to make his material easier to grasp by framing it in terms that most readers can understand based on their personal experience. Later, he also does this by expanding the range of texts he references as evidence. For example, he quotes from Leo Tolstoy’s novel, Anna Karenina, to make the point that many different factors are needed to bring any situation into perfect harmony. This helps him to make his point about the difficulty of domesticating animals. It also indicates that he is trying to appeal to readers who may have more familiarity with literary texts than they do with scientific or historical ones. Despite the level of scientific detail and analysis Diamond makes use of, he intends his text to appeal to readers without experience in these subjects, as well.

Diamond is careful to specify what kind of evidence he will need to make use of in order to answer the questions he raises. In this way, he continues to guide the reader and remains transparent about his methodology. For example, after raising the principle questions of this section, he notes, “Before we can hope to answer these questions, we need to figure out how to identify areas where food production originated, when it arose there, and where and when a given crop or animal was first domesticated.” This kind of statement gives readers a roadmap for the text to come; they know to expect that Diamond will explain the origins of food production, and the timeline of production. Moreover, he specifies the kinds of challenges that different types of evidence present. For example, the use of “radiocarbon is plagued by numerous technical problems,” which means that he will make use of other types of evidence as well in order to avoid leaning heavily on this one. Since this text makes use of such a wide range of evidence, it is important that Diamond is careful to chart and analyze his different methodologies.

At the end of chapter 7, Diamond makes a notable allusion to Darwin’s Origin of Species. He has just finished his description of how plant domestication first came about. Throughout this explanation, Diamond uses more scientific details than he has thus far in the text. He explains how plants typically reproduce, how this reproduction can be influenced by humans, and how natural selection means that certain plant features are preserved for further generations while others fade out of the gene pool. His allusion to Darwin’s text helps to orient readers. While many readers may not have a strong scientific background and may be thrown off by his explanations, most people have at least heard of Charles Darwin and the principle of natural selection. By referring to Darwin, Diamond gives his readers a better framework for understanding plant domestication; the "artificial selection" of agriculture is also influenced by natural selection. This allusion does not serve to make the text more relatable, but does help to support its points by connecting them to one of history’s most well-known scientists.

While the first four chapters of this section lay out basic background information, the next three chapters turn to more directly analyzing available evidence. Diamond is careful to cover necessary information on how plant domestication works, how animal domestication works, and how these two concepts were related. It is only after he has caught his readers up to speed on this basic science that he relates these concepts to the questions he raised at the beginning of the section. Namely, he uses this information about how domestication works to show how only certain areas of the world were able to develop domestication as quickly and efficiently as they did. Throughout this section, Diamond is able both to explain a number of scientific concepts and to demonstrate how these scientific concepts answer the core questions of his text.