The long-running series in which readers answer other readers’ questions on subjects ranging from trivial flights of fancy to profound scientific and philosophical concepts

Just when in history did the nebulous notion of “pop culture” as we know it actually begin? And what particular person or event kicked it off? Were there any D-list celebrities to venerate in the ancient world, for instance? RobertosMitch, via email

Send new questions to nq@theguardian.com.