Ross suspects they are an old dialect continuum, because they share numerous features that have not been traced to a single ancestor using comparative historical linguistics.

William A. Foley considers the TNG identity of the Irian Highlands languages at least to be established.

The Irian Highlands families (Dani and Paniai Lakes) appear to belong together, and the Timor and West Bomberai languages share two probable innovations in their pronouns, compared to the rest of TNG.

Wurm noted similarities with West Papuan, a different family, but suggested this was due to substratum influence.

[2] The words cited constitute translation equivalents, whether they are cognate (e.g. na-, nai- for “eat”) or not (e.g. mo, tani for “sun”).