speculative social institution theme
The story features a notable social institution of some sort that, for all intents and purposes, has not hitherto been extant in any human society. It may, for example, be premised on some technology or fantastical idea that humanity has not (yet) achieved.
Notes
A "social institution" in its broadest meaning is the activities of a large number of people that have banded together for some specific purpose. Typically it means that there is some recognized practice of doing something within a society. This may be related to education, business, governance, diplomacy, so on and so forth.