In this section, Diamond shows how the broad patterns he identified in the first three parts of the book apply to specific regional examples. He goes “around the world,” more closely analyzing the history of New Guinea, China, and Africa in contrast with that of Eurasia. He begins by returning to the case of New Guinea and Australia, in particular. One summer, Diamond vacationed in the Australian desert with his wife and experienced intense heatstroke. This experience led him to realize just how difficult it must be to live in this part of the world; how did people native to this region get by? It is also remarkable to note that modern humans most likely settled Australia before settling Western Europe. So, if these people had such a head start, why did Europeans end up conquering Australia, and not vice versa?
The comparison between New Guinea and Australia is a particularly constructive one. New Guineans lived at much higher population densities than Australians because they were food producers as opposed to hunter-gatherers. At first, it is hard to understand why New Guinean innovations did not spread to Australia, which was so relatively close to New Guinea. Overall, however, both New Guinea and Australia would be considered “backward” by modern people. Some white Australians believe this is because of supposed deficiencies of the Aborigines themselves; because they look different, maybe they are also genetically inferior. In fact, this supposition contains a number of logical errors that Diamond will illustrate by recounting the history of Australia and New Guinea.
Human societies in Australia and New Guinea originated from Asian societies, but went on to develop in isolation from these founding societies. So they make a good example of how environmental differences can cause even genetically identical peoples to develop along very different trajectories. Over time, New Guineans and Australians diverged genetically from these Asian ancestors, and from each other. This diversion reflects the very different environments in which these groups of people developed. New Guinea is a very fertile place, thanks to volcanic activity, glaciers that repeatedly advanced and retreated, and mountain streams that brought silt to the lowlands. Australia, on the other hand, has one of the oldest and most infertile soils of any continent because it lacked these ancient geographical patterns. These environmental differences shaped the two hemi-continents’ differing cultural histories. New Guinea was one of the world’s centers of independent origins of plant domestication thanks to its fertile soil. It went on to develop the most advanced technology, social and political organization, and art in Greater Australia.
But why did New Guineans stick to stone tools instead of developing metal ones, remain illiterate, and fail to organize into chiefdoms and states? Were they simply genetically primitive when compared to Eurasians who had the same environmental advantages? No; in fact, New Guinea had a number of biological and geographic challenges. First, their food production did not emphasize animal domestication, so it produced very little protein, which meant that highlanders had little muscle power available to cultivate complex crops. It also meant that the population failed to evolve epidemic diseases like those in Europe. They also had limited available area when compared to Eurasia, which kept their population density lower. The terrain was particularly challenging and they were engaged in intermittent warfare between different bands, which led to social fragmentation. Furthermore, New Guinea was geographically isolated, which prevented it from receiving the same inflow of technology and ideas as Eurasia did. New Guinea was advanced compared to the rest of Australia thanks to its environmental advantages. But it also had a number of disadvantages when compared to Eurasia, which kept it relatively “primitive” in comparison to Eurasian societies.
New Guineans were lucky when compared to Native Americans, however. They were not killed off to the same degree by European germs because there were no permanent European settlements in New Guinea until the 1880s, by which time medicine had advanced enough to bring such diseases under control. Instead, Europeans often suffered from the tropical diseases that existed in New Guinea. Their crops tended to do badly in the rugged terrain, as well—for these reasons, Europeans eventually left New Guinea to be ruled by New Guineans. They ended up colonizing Australia, instead, because it was suitable for European food production and settlement, and because European guns, germs, and steel were more effective in clearing Aborigines out of the way. Australia did not have as many serious diseases to drive Europeans away as New Guinea did. In fact, Europeans colonized Australia earlier than New Guinea, which meant they did introduce a number of then-still-lethal diseases that helped them to wipe out the Aboriginal population. It is important to note that white English colonists were not the ones who created a literate, food-producing, industrial democracy in Australia. They imported these elements from outside Australia, and were lucky to find that they could be translated to this continent. Europeans have never learned how to independently survive in Australia or New Guinea without bringing over their own technology. In this way, they fell short of the skills that native Australians and New Guineans displayed.
China presents another interesting case because it has been remarkably monolithic from the beginnings of its recorded history. Actually, China was once diverse, as all nations were, but was unified much earlier than most other nations. China “became Chinese” by homogenizing the huge region through the repopulation of tropical Southeast Asia, and the exertion of intense influence on Japan, Korea, and even India. China was one of the world’s first centers of plant and animal domestication, and may even have had two or more independent centers of food production. This helped it to become very dominant very early on. It developed a single writing system that then spread throughout the area. Other nations did make cultural contributions to East Asia, of course, and their influence should not be understated. But China had a disproportionate role, which makes it seem especially unified today.
In Polynesia, the role of food production in human population movement is made especially clear. Austronesian expansion in New Guinea ran a course opposite to that of Indonesia . In Indonesia, the indigenous population disappeared, most likely because of invaders arriving with deadly weapons and diseases. But in New Guinea, locals were able to keep invaders out. The invaders (Austronesians) were the same in both cases, and the New Guineans and Indonesians and Philippines were also genetically similar. The difference in outcomes is explained by geography. Indonesia was thinly occupied by hunter-gatherers who lacked even stone tools, while in New Guinea food production had already been established for years. Austronesians had few advantages in competing with New Guinean populations. Thus, they were able to triumph over native Indonesians, but not over native New Guineans.
Diamond also returns to the disparity between Native Americans and Europeans that he first explored in the beginning of the text. He applies the lessons learned from the previous three sections to explain that variations in food production also formed the basis of America’s disadvantages. Even in areas where agriculture was supported, it had five major disadvantages: dependence on protein-poor corn, hand planting of individual seeds instead of plowing with domesticated animals, lack of animal manure to increase soil fertility, and lack of animal muscle power for agricultural tasks. These differences in food production were the ultimate cause of disparities. Proximate factors included germs, technology, political organization, and writing. In terms of technology, Native Americans crucially lacked: metals used for tools in Eurasian societies, strong military technology, sources of power for operating machines, and sea transport. All of these disadvantages helped Eurasians to conquer the Americas, as opposed to vice versa. Overall, key developments in America were shifted to later dates because of: a later start, more limited options for wild animals and plants available for domestication, greater barriers to diffusion, and smaller or more isolated areas of human populations. In fact, Eurasians first tried to colonize the Americas around 1300 A.D, when Norse peoples traveled to North America. This first attempt failed, as the harsh climate killed Eurasians off. The only reason the second Eurasian attempt succeeded was because it involved a source, latitude, and time that made Europe’s potential advantages very effective. Circumstances were crucial to shaping conquest.
Finally, Diamond revisits the question of why we think of native Africans as black. In fact, very different peoples occupied much of modern black Africa until a few thousand years ago, and even “African blacks” are very heterogeneous. These diverse peoples resulted from Africa’s diverse geography and long prehistory. But blacks became most widespread, rather than the four other groups that existed there, thanks to their ability to better subjugate these other peoples. Some people were “luckier” than others because of the available domesticable wild plant and animal species they inherited from their environment. These lucky Africans were able to use their advantage to engulf their neighbors. Overall, Africa did have a number of disadvantages relative to Eurasia, however. These included: a lack of domestic animals and plants, a smaller area, and a different orientation of main axes. Because of these factors, Eurasians were able to colonize Africa as a whole, after this original process of some Africans having engulfed others on the continent. These accidents of geography and biogeography drove African history.
In this fourth section, the scope of the text shifts back to a focus on specific continents, which Diamond considers one at a time. He begins with New Guinea and Australia, in particular. However, even while the scope is narrowed to analyze individual continents, the analysis remains broad. Diamond applies the lessons learned in the first three sections to these case studies in order to show how each continent can be analyzed using the framework he has built. He explicitly tells his readers that “Australia is the logical continent with which to begin our around-the-world tour, applying the lessons of Parts 2 and 3 to understanding the differing histories of all the continents.” Thus, readers should approach these descriptions of Australia with the “lessons of Parts 2 and 3” in mind. In other words, they should consider how Australia fits into patterns involving the importance of food production in spurring earlier germs, technology, and political centralization. Readers should also be prepared to revisit the book’s original question, first posed by Yali, about why Europeans developed so much cargo while New Guineans did not; this question will finally be answered in more detail in this fourth section.
Diamond makes more use of visual evidence in this section. As he discusses the unique trajectory of China, he illustrates his point about the country’s surprising level of diversity by showing the range of languages in a linguistic map. The map uses grey, shaded areas to show the distribution of the eight major language families. It also makes use of darker, smaller dots throughout the country to show where the 130 “little languages” were mainly concentrated. This visual helps to illustrate that, while China may have seemed homogeneous in a number of ways, it did have a smattering of heterogeneity that is important to note. This kind of visual evidence is important to look out for throughout the text, because it helps to reinforce Diamond’s major points. Since much of Diamond’s argument engages with geography, it makes sense that he employs numerous maps to support his explanations.
As he concludes his focus on East Asia and the Pacific, Diamond explicitly lays out the stakes of these two chapters. He explains that “to anyone interested in world history, human societies of East Asia and the Pacific are instructive, because they provide so many examples of how environment molds history.” Again, Diamond returns to the central point of the book: it is the environment of different areas that determines these areas’ differing trajectories when it comes to development. His exploration of East Asia and the Pacific serves to bring a new angle to this main argument by providing more specific examples of the ways in which differing environments shaped the historical course of these places. He is careful to connect this evidence to his overall argument and analysis, thus keeping the focus on his main idea throughout the entirety of the text.
The book concludes where it began by revisiting early questions. This time, Diamond recalls the issue of why Europeans managed to reach and conquer the lands of Native Americans, as opposed to vice versa. He entreats his readers to, “now return to the collision of hemispheres, applying what we have learned since Chapter 3.” In this way, Diamond brings his text full circle. He shows how the first sections of the book provided important frameworks for understanding its original questions, and brings these two aspects together around the theme of the “collision of hemispheres.” In this fourth section, the collision helps to show the practical consequences of uneven development; because Europeans developed germs, steel, and guns before Native Americans did, they were able to subjugate these native peoples.
The last chapter of the section does, however, acknowledge a certain degree of simplification. Diamond provides a table meant to illustrate the course of human history through a series of events and dates. He notes, however, that “this table is sure to horrify any knowledgeable scholar, because it reduces complex histories to a few seemingly precise dates. In reality, all of those dates are merely attempts to label arbitrary points along a continuum.” It is important to note Diamond’s acknowledgment of simplification; throughout this book, which attempts to compress the whole of human history into a four hundred page text, Diamond necessarily simplifies many concepts. He knows that the most knowledgeable scholars in his audience may bristle at this simplification. However, Diamond is not writing only for expert scholars. Instead, he is attempting to explain science and history in terms accessible to the average reader. Thus, a table like this one helps to illustrate, for the non-expert reader, the evidence he otherwise recounts mainly in the form of anecdotes. Nevertheless, it is important not to view such presentations of scientific or historical evidence as absolute, complete, or perfectly decisive; Diamond is interested in establishing broad patterns, which sometimes means glossing over certain scholarly details.