I was going through Timeline of social nudity ( wikipedia ). There is a sudden gap of a thousand or so years after which suddenly nudity is a big no-no.
Why did it evolve into something to be frowned upon?
/u/AnnalsPornographie has previously answered When/why did "private parts" become so private? under a previous alias.
EDIT: forgot this answer was written under a previous username. AnnalsPornographie is the most recent avatar.