The answer to Yali's question forms the central thesis of Guns, Germs, and Steel. Yali, a local leader in Papua New Guinea, asked Jared Diamond (the author) the following question in 1972:
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?
According to Diamond, Yali's people had only recently (as in a couple of centuries ago) lived in the Stone Age, in the sense that they still used simple stone tools, survived as hunter-gatherers, and lived in small villages. So what Yali was asking Diamond, a scientist visiting the area on a research trip was, "Why did Europeans develop the complex technology that enabled them to expand their influence around the world? Why didn't this happen in Papua New Guinea?" Diamond's answer to this profound question is complex, and he summarizes it as follows:
History followed different courses for different peoples because of differences between peoples' environments, not because of biological differences among peoples themselves.
Europeans developed the technologies that we associate with modern life because they lived in regions possessing geographic and climactic characteristics that were amenable to the rise of settled agricultural societies. In other words, what we think of as "civilization" is not the result of racial, intellectual, or cultural differences between peoples, historical or modern. Europeans developed the "guns, germs, and steel" necessary for conquering peoples around the world by geographic accident.