Jared Diamond, the author of GGS, starts out the book with a good question. What makes the difference between conquered and conquering societies? Why was Europe the continent that took over and subdued others, rather than the other way around? Why didn't Kenya take over England, or Peru sail across the ocean to colonize Spain? Sure, the Europeans had weapons (guns), diseases (germs) and technology (steel) in their advantage, but how did they gets those advantages in the first place? Some in the past argued that there was a fundamental difference between the peoples of these countries—Europeans were more innovative, more curious, more intelligent than the average African. Diamond calls this racist, and puts forth a different, geographically based theory.
Basically, people who happened to live in Europe had several advantages over people living on other continents. The biggest advantages were the presence of wild plants and animals on the continents of Europe and Asia that could be domesticated (unlike Africa—no one has yet domesticated the cape buffalo, or rhinoceros, or even the zebra). This led to increased food production which led to the ability to feed larger groups of people—not all had to be hunters/gatherers and now some people could focus on technology and invention. Living in close proximity to animals gave Europeans contact with a variety of diseases (cow pox becoming small pox, influenza from swine flu, etc) and subsequent immunity. Also, because Europe is a wide continent instead of a tall continent (east to west axis instead of north to south) the food and animals that were domesticated could easily spread across the continent. Contrast this with food developed to grow in Mexico trying to thrive in Alaska, for example. So it's not that Europeans are superior to other races, they were just in the right place to thrive, according to Diamond.
In the end, it was probably a good book to read although it can't come as highly recommended as Strength in What Remains! But for Westerners working in Africa, I have to fight against the temptation to buy into the idea that our ways are "superior" over African methods. Look! We were able to develop better societies than our African counterparts. Which, of course, is not necessarily true, and even if my ancestors developed technologies and societies faster than my Kenyan coworkers' ancestors, it is not based on some inherent cultural or genetic superiority but rather, as Diamond states, better real estate.