爹娘

爹 and 娘 are two words that intrigue me. It seems, from the movies I’ve wathed (活着/To Live being a prime example) that up until very recently they were the usual words for dad and mum. Now 爸 and 妈 seem to be most common. But I still occasionally hear even young people out in Yanqing use 爹 and 娘. I’m kinda curious about the origins of these words. Exactly how long have 爸 and 妈 been in use, and where did they come from? Cursory searches through google and Baidu Baike don’t turn up much information.