Our Ice Age ancestors in Europe, 15,000 years ago, may have used words we would recognize today, according to a new study out this week in a US journal.
Words that sound alike in related languages are generally assumed to have come from a common route, like "father" in English and "pater" in Latin.
Lead author Mark Pagel, an evolutionary biologist at the University of Reading in Britain, and his team were able to take the analysis a step further by showing that certain very commonly used words, like pronouns, are more likely to stay the same over the millennia.
"We discovered numerals, pronouns and special adverbs are replaced far more slowly, with linguistic half-lives of once every 10,000 or even more years." Pagel explained.
In other words, everyday words like "I, you, we, man and bark," have, in certain languages, the same meaning and nearly the same sound as they did thousands of years ago.
Their analysis suggests that at least seven major language families in Eurasia all descended from a common ancestor language.
"As a rule of thumb, words used more than about once per thousand in everyday speech were seven to ten times more likely to show deep ancestry in the Eurasian super-family," Pagel said.
Focusing on these common lexical items helped the British researchers avoid a common pitfall of historical linguistics -- that it is difficult to distinguish between words that sound alike because of common ancestry and words that sound alike because of simple coincidence.
For instance, "team" and "cream" in English are unrelated, but sound quite similar.
But the everyday words were statistically likely to be related, and so when the researchers found ones that sounded alike, they were able to conclude with fair confidence that it was not simply by chance.
The latest study was published Monday in the Proceedings of the National Academy of Sciences.
Pagel's previous research had looked into the evolution of more than 7,000 Indo-European languages, looking for shared patterns in how language is used and why some words stay in use while others disappear over time.