Guns, Germs, and Steel: Epilogue Summary & Analysis

Diamond now returns to the question Yali asked (the question brought up at the beginning of the book): “Why is it that you white people developed so much cargo … but we black people had little cargo of our own?” the answer to Yali’s question is this: “The differences between the long-term histories of peoples of the different continents have been due not to innate differences in the peoples themselves but to differences in their environments.”

In particular, there are four underlying environment factors that determine the course of human history: 1) availability of wild plants and animals for domestication, 2) barriers to diffusion and migration within a continent, 3) barriers to diffusion and migration between continents, and 4) population size and density. Factor 1 is especially critical in determining a society’s nutritional intake and health, its immunity to disease, and its amount of social specialization. Factors 2 and 3 are especially important in determining a society’s “stockpile” of technology, including a written alphabet. Finally, Factor 4 is important in determining a society’s level of political centralization, as well as its immunity to disease.

There are some notable caveats to Diamond’s conclusions. Most basically, Diamond’s book is too short to account for all of human history—it’s simply not possible for any one book to talk about 13,000 years of history.

Another important caveat to Diamond’s conclusions is the supremacy of Europe over China and the Fertile Crescent. Why, exactly, did Europe overtake China and the Middle East as a world leader, given that all three regions had comparable advantages in the four geographic factors Diamond lists above? Specifically, why was it Europe, not China or the Middle East, that developed mercantile and capitalist economies, which allowed for world exploration and technological research?

A partial answer to this question is that the Fertile Crescent lost its geographic advantages over time. As it entered the modern era, Mesopotamia became drier, the soil became less fertile, and the region as a whole ceased to be a major producer of food. Most of northern and western Europe has continued to produce crops and livestock for thousands of years.

Why was it Europe, not China, that became a world leader in the late 15th century? One would think that China’s huge technological innovations (the compass, printing, gunpowder) and sophisticated navy would have made its global influence and domination inevitable. Yet China mostly gave up its maritime expeditions in the middle of the 15th century. China was a politically unified country at the time; the dynastic powers ruled that China would no longer explore the rest of the world with its ships. Because of the stability of Chinese society, one dynastic decision determined the course of Chinese foreign policy for the next 400 years, thereby allowing Europe to seize power in the New World without any Chinese competition.

In Europe, there was much less political unification than in China. One reason for this is that Europe itself is a more geographically fragmented region than China. China is one solid landmass with long rivers and a relatively few islands; Europe has large islands, mountains, and small rivers that don’t connect together the entire continent. So it’s possible that China, because of its geographic unity, became more politically unified than Europe. As a result, there were power squabbles in Europe, resulting in death and destruction, but also more competition between nation-states. Competition inspired Western European nation-states to invest large sums in exploring the New World—the states were worried that their rivals would overtake them. This analysis, perhaps, begins to explain why Europe, not China or the Fertile Crescent, came to dominate world exploration after the 15th century.

Another important caveat to Diamond’s argument is the role of culture in history. By and large, the book avoids talking about cultural differences between different peoples of the world, preferring to frame its conclusions in terms of geography. Yet there are undeniable differences between different cultures, which may be the product of environmental factors. This is an important topic, but beyond the scope of Diamond’s book.

Similarly, Diamond’s conclusions don’t account for individual people. Sometimes, a single, unpredictable person, like Lee Harvey Oswald (who assassinated President John F. Kennedy) can change the course of human history; Oswald’s actions (or the actions of any other single, historically important person) don’t seem reducible to geographic causes. Diamond concludes, “it remains an open question how wide and lasting the effects of idiosyncratic individuals on history really are.”

During the book, Diamond has aimed for a scientific approach to the study of history, while respecting the basic differences between science and history. Science is a study of causes and effects; using experiments, scientists aim to isolate which causes are linked to certain effects. In history, it’s often difficult to isolate the causes of historical events—there’s no “experiment” that historians can use to identify an independent variable’s effect on a dependent variable. Nevertheless, there are certain approaches that historians can take to studying their data that make their approach more scientific. For example, historians can compare civilizations that are environmentally similar, thereby doing a better job of isolating the relationship between causes and effects. (Diamond has spent most of his book trying to isolate the various causes of differences between civilizations.) In general, history is a complex field—in a way, much more complex than any of the sciences, because there are so many different causes to analyze. Nevertheless, it’s important to study history scientifically so that we can understand how the modern world came to be the way it is.