At the beginning of Guns Germs and Steel Jared Diamond talks about and encounter he had with a colleague, in New Guinea. While he was discussing various topics his colleague, Yali, inquired as to why white people had so much cargo but blacks had so little of their own. The answer is not entirely revealed in this book although Jared Diamond does list many factors that could have affected this development of early societies.

The factors that Jared Diamond explains in depth about why history happened the way it did, are almost "in layers." What I mean by this, is that first there are the ultimate factors, the factors that start everything off. These are the factors to which other, proximate, factors can be linked. These proximate factors are the more recent factors that were "by-products" of ultimate factors.

I believe that there are three ultimate factors in...