What are the main concepts Diamond brings up in Guns, Germs and Steel which later Mann expands on in 1493?

The central argument
of Diamond's classic work on world history and social anthropology is based around his central
argument that attempts to respond to "Yali's Question," an acquaintance of his who
asked Diamond one day why it is that the whites in the world had done so well and achieved a
position of supremacy over other ethnicities in the world. Diamond's answer to this question is
fascinating in so many ways, but it principally states through his research and hypothesis that
supremacy in the history of man is not due to differences of ethnicity but due
solely...