If you've never heard anyone speaking Ayapaneco, you're not alone.

Though the language has been spoken in what is now Mexico for centuries, there are only two people left who can speak Ayapaneco fluently. Like so many other indigenous languages, it's at risk of extinction -- even more so because, as the Guardian reports, the last two speakers are refusing to talk to each other.

Though it is not clear what lies behind their mutual avoidance, Manuel Segovia, 75, and Isidro Velazquez, 69, live 500 metres apart in the village of Ayapa in the the southern state of Tabasco. The two have reportedly never enjoyed each other's company.

But now, Daniel Suslak, a linguistic anthropologist from Indiana University, is planning to produce a dictionary of Ayapaneco in an effort to revitalize the language before it is too late, the Sydney Morning Herald reports.

Other indigenous languages are also at risk of extinction. View some of the world's most endangered languages here: