The researchers first had to find cognates across the languages – words that come from a common original source and maintain the same meaning and similar sound, or have undergone predictable changes.
Consider the word "fart." Fart, while it did not appear to pass muster in this paper, comes from a highly respectable linguistic lineage — it crops up as furzen in German, frata in Old Icelandic, perdet’ in Russian and pardate in ancient Sanskrit. Overall, speakers of these languages can’t understand one another — and yet, the word "fart" remains in remarkably good shape (if you take into account that Ps frequently turn to Fs in certain language groups).
But reconstructing words for long-dead languages is tricky business. Most words evolve too rapidly, and have a 50-50 chance of being replaced by a noncognate every 2,000 to 4,000 years.
Luckily, some words — like numbers, pronouns and special adverbs that see frequent use — seem to have much longer half-lives of every 10,000 to 20,000 years.
They discovered a number of words — "this," "I," "give," "mother," "hand," "black," "ashes," "old," "man," "fire" — that cropped up in similar form across at least four of the seven language families studied across Eurasia. They traced them back to 15,000 years — right around the time the glaciers would have been melting, allowing humans greater ability to spread out over the globe and for languages to start to diverge.
So if you ever have the unusual opportunity to say this to someone from the Ice Age — "Black ashes? Who is this old man? Mother, I hear fire!" — there’s a fair chance they’d get the gist of things.
"Our results suggest a remarkable fidelity in the transmission of some words and give theoretical justification to the search for features of language that might be preserved across wide spans of time and geography," the authors write.
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