Grammarphobia got a question about the use of the word “man” by people referring to each other during the Jazz Era to counter the belitting use of “boy”, and whether it originated before that. The answer: yes.
[…] In fact, the usage dates back to Anglo-Saxon days, though its sense has evolved over the years.
When the usage first appeared in Old English, it was “used to address a person (usually a man, but sometimes a woman or child) emphatically to indicate contempt, impatience, exhortation, etc.,” according to the Oxford English Dictionary.
The dictionary’s earliest example, which we’ve expanded, is from the “Vercelli Homilies,” 23 prose homilies in the Vercelli Book, an anthology of prose and poetry probably collected in the late 10th century but originating earlier:
“cwæð sanctus ysodorus, geþence nu ðu, man, & ongyt gif ðu sylf þe nelt alysan þa hwile þe ðu miht” (“Saint Isidore said, ‘Now think, man, and consider if you don’t want to release yourself [from a sinful life] while you can”).
Damn, man! Ain’t language fascinating?