Why has Diamond chosen to write Guns, Germs, and Steel in this style?guns germs and steel preface

Diamond does not ever tell us in the preface why he has
chosen to write in the style that he uses.  We must simply try to infer why this style
would be useful to him.

First, let us characterize his
style.  We can say that it is an informal and not very academic style.  So, why would he
want to write in such a style?  The reason that I would suggest is that Diamond wants
the average reader to be able to enjoy his book.  He does not want the book to read like
a textbook because he wants it to be accessible to people who are not in
academia.

I would argue, then, that Diamond chooses his
style because he wants the book to appeal to a wide variety of
readers.