How does the fact that writing systems developed differently in Eurasia than other continents fit into the thesis of Guns, Germs, and Steel?

Diamond argues that Eurasian countries had much more
widespread writing.  These countries had literate bureaucracies and generally had a
significant portion of the general population that was literate.  This meant that
writing allowed these societies to advance more than others in terms of political
structure, economics, technology, and other things.

This
fits well with Diamond's thesis because it shows the importance of having discovered
writing early.  Societies that did so were able to spread writing among their population
and really use it to make themselves more powerful.  This allowed them to use writing to
help dominate other countries that did not become literate as
soon.

Diamond's major thesis is that the earlier adopters
of technology (chosen by geographical factors) were the lucky ones.  These were the
societies that became powerful and dominated the others.  Writing was one of these
technologies whose early adoption helped make Eurasian societies
dominant.