Alternately: when we developed warehousing. Grain houses, meat salting, anything that allowed long-term storage allowed hoarding. Manual labour then shifted fro

Alternately: when we developed warehousing. Grain houses, meat salting, anything that allowed long-term storage allowed hoarding. Manual labour then shifted from subsistence-related activities to protecting the stash, and that means you need a power structure to decide who gets access to what part of the riches.