What role does surplus play in the development of civilizations?

Answer 1

It created social stratification. A class of people who gained control over most of the surplus emerged. A class of poor people was exploited for the production of the surplus, most of which was acquired by the rich. A power structure formed and it would became centralised, leading the formation of the state. This was headed by a king or a similar figure and rich aristocracies or oligarchies wielded great influence on it. Sometimes one the latter two took over. More efficient methods of production were promoted in Sumer and Egypt and more efficient systems for its collection were also developed. The state needed to undertake public works for the development of infrastructure. Conspicuous expenditure for impressive buildings were made affordable by revenues form the surplus. Armies created for defence were often used for conquest and the acquisition of the surplus of other peoples was a common motivation for this, although geo-political strategic considerations were often a factor,too.