So I recently read about how Homer uses words like dark-wine to describe the sea because ancient Greek did not have a word for blue. I was wondering if there is any evidence of something similar happening with emotional concepts, like how there is no word in English for the Japanese concept of 'mono no aware'.
I guess that the words for "basic" emotions like anger and happiness have always been there since there is written language, but is there evidence of the sudden development of new, more complex emotional concepts at some point in the past?
ancient Greek did not have a word for blue
I don't think I can really answer your question (other than to say none of the several ancient languages I know have any trouble expressing complex emotional concepts) but this myth has to die. Greek has perfectly good words for the color blue. The Homeric Poems are poetry, they do not use uninteresting, prosaic descriptions--consider that Homer rarely uses color terms of any kind at all. It's not even certain that οἶνοψ refers specifically to color, as it should mean something like "winey" (although Homer also uses it of the coats of oxen). There are several discussions on this sub on οἶνοψ, the best of which was written by a flaired user who has since deleted his comment (and thus I do not feel comfortable linking to it). No classicist of any repute seriously thinks that Greek lacks a term for blue, since any classicist should have learned Greek well enough to know that