I don't know for sure about scholarly work on memes, but language changes over time. Language is used to convey ideas, and in turn is changed, shaped by which ideas need to be represented in different cultures and different times. Maybe on some level you could consider components of language (words, grammatical rules) to be that discrete unit.
Not unless you want to confine memes to language. Memes are intended as general units of cultural inheritance - and are not specific to language.
My two cents on the subject may be found in the article: Are memes discrete?.
I don't know for sure about scholarly work on memes, but language changes over time. Language is used to convey ideas, and in turn is changed, shaped by which ideas need to be represented in different cultures and different times. Maybe on some level you could consider components of language (words, grammatical rules) to be that discrete unit.
Languages definitely have been classified phylogenetically/cladistically. Drift and change eventually leads to different languages stemming from a common ancestor. See for instance Indo-European languages or even Nos... (read more)