Hmm well for the ancient greek one it was anthropology and languages based professor/researcher who discovered this. What I would do is some investigation of my own. Like maybe you guys have a tradition that when you mentioned to uni friends they all went no we doont do that? And if you look that up (google is best friend

) it might be related to an old tradition lost is time. And then find ppl who are researching that (send email). That's pretty much how the ancient greek one was found. One of the residents realized (after leaving the village) that they dont speak same langauge as rest of the country.