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Of that enormous group of languages, most belonged to the Pama-Nyungan family, with dozens of branches that descended from a protolanguage probably spoken 6,000 years ago in the northeastern part of the continent.

If Hale was right, then Pama-Nyungan, with more than 200 identified languages, would be one of the world's largest language families—larger than Indo-European and almost as large as Sino-Tibetan.

That suggests that Pama-Nyungan languages developed much as other world languages did, rather than being a rarefied case, she argues.

Some suggested that the Pama-Nyungan family, if it exists, entered the continent in a separate migration, whereas others argued that it split off from other Aboriginal languages only a few thousand years ago.

They analyzed 36,000 words from 195 Pama-Nyungan languages and compared the loss and gain of cognate words in 189 meanings through time.