system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why do we build rectangular houses and not round houses?

I mean houses in Europe and America have 4 corners (or more) whereas in Africa Natives build round houses (also in Asia afaik). 
Do they have any advantages or disadvantages? Or is one solution cheaper, ...?
gpt
They fit together more efficiently. Humans switched from round houses to rectangular ones around about the time the first cities started forming. It was purely for efficiency but it caught on over millennia.