Guns, germs, and steel : the fates of human societies by Jared Diamond offers a theoretical overview of the developement of human societies and technology. I dont't recall him specifically addressing the issues of the thread but he does talk about the dynamics of domestication and how that lead to the establishment of settled cites and larger polictical groupings.
I think agriculture allowing for specialization led not only to prients, ruler, and warrior classes but also to philosophers and it also required some adaptions that would occur along similiar lines. There was also trade and that could very slowly spread ideas between far flung cultures.
lfen
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