While the eNotes summary of Guns, Germs, and Steel does not have a summary for the Epilogue in its chapter summaries, I can provide one for you here.
The Epilogue of this book begins with a brief recap of the geographical differences that are, in Diamond’s mind, most useful for answering Yali’s question. Diamond says that the following four factors do the most to predict which areas of the world would become rich and powerful:
- Number of domesticable plant and animal species. Places that have more species that can be domesticated are more likely to develop agriculture.
- The direction of a continent’s axis. An east-west axis allows crops and other innovations to diffuse across a continent. A north-south axis makes this harder.
- Ease of diffusion between continents. People in Europe and Northern Africa, for example, are more likely to benefit from developments in the Fertile Crescent than people in the Americas are.
- Area and population size. Places with large areas and populations will have more potential innovators, more competition, and more of other factors that drive development.
Having told us what geographical factors are most important, Diamond now turns to a discussion of what could come after this book. In other words, what research could be done to follow up on this book? He discusses five main directions for further research:
- More data about differences between continents. Diamond has investigated some differences (like the differences in numbers of grain species), but he says further research could provide more data about the ways in which the continents differed.
- Research on smaller areas or time periods. Diamond suggests studying how/if geography affected smaller-scale things such as why the Fertile Crescent lost its lead over the rest of the world early on or why China did the same later. He makes a long digression here, saying that the Fertile Crescent lost its lead because its ecosystems were fragile and that China lost its lead because its homogeneous geography allowed a large empire to stifle all competition that would have led to greater development. But the main point Diamond is trying to make here is that researchers could try to determine whether geography affects things other than the biggest trends in human history.
- Impact of cultural differences. Diamond says that some cultural differences have nothing to do with geography. Do those differences affect history and, if so, how much?
- Impact of individuals. How much impact do single people have on history?
- How can we make history more scientific? Diamond is a scientist by training and wants to encourage historians to be more scientific in their thinking and research.