In Guns, Germs, and Steel, Jared Diamond sets out to explain why people from Eurasia, and not people from other continents, conquered much of the rest of the world. At the outset of the book, Diamond rejects the idea that any moral, intellectual, or genetic factor could have produced a race of inherently superior people. Instead, he argues that environmental and geographical factors allowed Eurasians to advance faster than their counterparts elsewhere.

Diamond explains that he became interested in exploring the historical inequalities between human societies in July 1972, when he was studying bird evolution in New Guinea. One day, he was walking along a beach, and he struck up a conversation with a charismatic New Guinean politician named Yali. In New Guinea, people were still using Stone Age technology when European explorers arrived 200 years ago. New Guineans immediately recognized the value of European tools, weapons, clothing, and so on, which they referred to as cargo. Yali asked:

Why is it that you white people developed so much cargo and brought it to New Guinea, but we black people had little cargo of our own?

Diamond could not answer Yali’s question. However, Diamond felt immediately that it was an important question—especially when he considered it on a world scale and not just as a comparison between Europeans and New Guineans. Diamond expands the question as follows:

Why did wealth and power become distributed as they now are, rather than in some other way? For instance, why weren’t Native Americans, Africans, and Aboriginal Australians the ones who decimated, subjugated, or exterminated Europeans and Asians?

As he begins to attempt to answer these questions, Diamond notes that the archaeological record suggests that technology on all of the habited continents looked about the same in 11,000 BCE, at the end of the last ice age, but that something changed after that. By 1500 CE, Eurasians had developed far more technology than the residents of other continents. Diamond states that he wants to explain why technology and society developed so differently on different continents.

Before beginning his argument, Diamond pauses to refute several possible objections to his line of questioning. He points out that he is seeking to explain why Eurasians became so dominant in the world, not to justify the behavior of colonialists. He promises to describe interactions between non-European racial groups, not just between European colonialists and others, to avoid a Eurocentric worldview. Finally, he claims that he does not consider technological societies inherently better than hunter-gatherer societies. He merely makes an effort to understand why technological societies have tended to conquer their hunter-gatherer neighbors and why some societies developed more technology on their own than others did.

Diamond claims that his book is an important replacement to earlier books about human societies, which do not try to explain why history played out the way it did. He feels that in the absence of a coherent explanation for these events, students of history are too likely to fall into conscious or unconscious assumptions of inherent racial, moral, or intellectual differences between peoples. Diamond’s own interactions with modern hunter-gatherers on biological research trips have led him to believe that there are no such inherent differences—and if there are such differences, he feels that the hunter-gatherers have a slight edge.

Diamond goes on to consider and refute a few other arguments about why Eurasians developed more technology than anyone else had by 1500 CE. He does not believe that Eurasian technologies advanced because of cold weather or because of early societies’ placement around rivers. He says that previous historians were on the right track when they proposed that the existence of Eurasian weapons, steel, manufacturing, and infectious diseases enabled Eurasian dominance. However, Diamond points out that these theories do not explain why Eurasians had technology and diseases that the members of other cultures did not. Why did this set of elements arise in Eurasia and not in Africa, where people had lived the longest?

In answer to this question, Diamond proposes that environmental differences between the continents made the faster advancement of Eurasia’s people inevitable. He says his extensive background as an evolutionary biologist—along with his curiosity, sparked by Yali’s question—make him the right person to explain why.