I'm pretty sure than polygamy differs from communal living, in that a communal arrangement doesn't necessarily involve sex or marriage. When I was at uni, I shared a house with eight other people of assorted genders. While I can't say that there were no hook-ups (it was none of my business), but I never had sex with anyone in the house. But it was 'communal' in the truest sense of the word - we all shared resources and responsibilities to keep the house running.
Boru
Boru
‘I can’t be having with this.’ - Esmeralda Weatherwax