The evolution of disease
In his book, Diamond analyzes how various nations have been affected by disease. He explores why some nations were more vulnerable to transmitted disease than others. Every geographical region has its own particular illnesses and disease; over time, the people living in that area build immunity to those diseases. When groups of people began traveling to other continents, they carried with them the diseases to which they had developed immunity, and ended up infecting these other nations with their unique diseases. In order to develop, illnesses that primarily spread in epidemics required a dense population, and close contact between humans and animals. Diamond links the development of new diseases and the birth of new illnesses with human progress because when humans began to gather in large groups and live as a community, they made it easier for disease to spread and become even more aggressive.
The appearance of agriculture and farming
Diamond spends most of his book talking about agriculture and farming, and how it influenced humankind and society in general. In the beginning, humans were hunters and gatherers but, over time, they realized that raising certain animals in enclosed spaces and planting the seeds from the plants they ate could save energy and allow them to focus on pursuits other than tracking down food. The world as we know it today would have never existed if our ancestors did not learn how to raise animals and how to breed plants to better suit their needs. However, the existence of agriculture also explains disparities between different human societies. Those who remained hunter-gatherers did not progress technologically; since agriculture allowed for more supplies of food, it built denser populations with more time for specialization and innovation. Thus, those who developed agriculture also pulled ahead, in terms of technological advances and manpower, of those who did not.
The impact the environment has over evolution
From the beginning, Diamond makes clear that he doesn’t believe that people from one continent are generally less intelligent than those from another. The idea that racial difference might explain differences in intelligence and productivity was promoted by the white European settlers who colonized other parts of the world. Diamond argues that the reason some nations developed more rapidly than the others had nothing to do with people’s relative intelligence, but rather with their geographical location. Europeans had access to fertile lands for farming, raw materials such as iron and wood, a favorable geographical environment that allowed them to communicate and trade with other nations, and also a large number of mammals that could be domesticated and used for food and agriculture. All of these elements created a favorable environment for the development of disease, technology, and social complexity. For this reason, European countries had weapons and better means of conquering other nations. The impact of the environment on all features of human development is a crucial theme of Diamond's work.
Ecological barriers
In the first part of his text, Diamond points out that a lack of ecological barriers was generally an environmental advantage for a given continent. For example, the ability to move people, ideas, plants, and animals across the Eurasian continent allowed this continent to develop at a faster rate than others, since the advances of one area could be spread quickly to other areas. In this sense, having loose ecological barriers was favorable to development. However, Diamond also points out that a lack of ecological barriers could actually become a disadvantage in some cases. For example, in China, a relative lack of ecological barriers meant that the country could unite politically under one leader. Though this may have made them stronger and more unified at first, it presented a disadvantage when it came to adopting and keeping new technology. China turned its back on maritime technology after a new leader came to power who did not believe in its potential. Because of the decision of a single leader, the entire country lost this incredibly important technology. Thus, Diamond shows that ecological barriers can be either an advantage or a disadvantage, depending on context.
The broad patterns of history
Throughout his text, Diamond focuses his energy on tracing the broad patterns of human history. This is important to note because it stands in contrast to a possible focus on historical details. Though Diamond does occasionally provide details in his examples, he largely sticks to a broader scope. One of his major themes is the larger picture of human history; he is most interested in tracking the general progress of one community in comparison to another, which means that he focuses mainly on the broad patterns of our history. Diamond repeatedly reinforces this theme by reminding readers that this is the ultimate aim of most of his individual examples. Occasionally, he refers to the importance of this theme as a means of defending his text from criticism for glossing over details.
The common origins of humanity
One of the most important points Diamond makes in his text is that all of humanity shares common origins. In the beginning, everyone evolved from the same starting point and was part of the same original human community. It was only over time, as people moved into different areas of the world, that differences arose. This is an important point to keep in mind because it ties into Diamond's emphasis on the importance of environment; if differences only cropped up when people moved across the world to live in separate areas, then it logically follows that these differences can largely be attributed to different environments. Indeed, Diamond will show that areas with access to more domesticable plants and animals were able to develop agriculture first, and thus also developed more dense populations, more technology, and more diseases.
The frustration of native peoples
Diamond continuously references his personal encounters with frustrated native peoples striving to understand why their ancestors were subjugated by Europeans. In the beginning of his text, Diamond quotes the New Guinean politician Yali, who asks him why white men developed more "cargo" than the New Guineans. Toward the middle of the text, he also references the frustration of a Native American named Levi, who worked for a Swiss farmer and expressed his anger that the Swiss had come to America and oppressed his people so many years ago. This frustration is an important theme in the book, since it speaks to one of Diamond's central points: the subjugation of one people by another was not due to any inherent defects in those who were subjugated, but rather to the misfortune of circumstances. Yali and Levi's people were the ones who were dominated because their environments had not promoted the early development of domestication, technology, and infectious disease. Of course, today, they are frustrated by the ways in which their ancestors suffered from the consequences of these environmental disparities.
