Science News has a fricative breakthrough – biting off a bit of linguistic evolution that took place when we started growing our own food rather than hunting and gathering whatever we could find. That leap in culture also caused a change in our jaw muscles, which meant that we pronounced things differently enough to give our languages whole new sounds:
People who regularly chew tough foods such as game meat experience a jaw shift that removes a slight overbite from childhood. But individuals who grow up eating softer foods retain that overbite into adulthood, say comparative linguist Damián Blasi of the University of Zurich and his colleagues. Computer simulations suggest that adults with an overbite are better able to produce certain sounds that require touching the lower lip to the upper teeth, the researchers report in the March 15 Science.
Linguists classify those speech sounds, found in about half of the world’s languages, as labiodentals. And when Blasi and his team reconstructed language change over time among Indo-European tongues, currently spoken from Iceland to India, the researchers found that the likelihood of using labiodentals in those languages rose substantially over the past 6,000 to 7,000 years. That was especially true when foods such as milled grains and dairy products started appearing.
“Labiodental sounds emerged recently in our species, and appear more frequently in populations with long traditions of eating soft foods,” Blasi said at a March 12 telephone news conference.
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[I]n 1985, linguist Charles Hockett argued that hunter-gatherer languages virtually never include labiodental sounds. That’s because by young adulthood, heavy tooth wear from intense chewing of tough foods triggers dental changes that move the upper teeth directly on top of the lower teeth, he contended. A resulting “edge-to-edge” tooth arrangement makes it harder to form labiodental sounds, Hockett reasoned. If true, his proposal meant that the introduction of soft foods in farming societies should have safeguarded overbites and raised the likelihood that spoken languages would include labiodentals.
The new study’s computer simulations support Hockett’s idea. They show that a transition from an edge-to-edge bite to a slight overbite makes it substantially easier to utter labiodental sounds.
What’s more, a statistical analysis of languages and lifestyles for more than 2,400 populations around the world found that, on average, hunter-gatherers use about one labiodental sound in their speech for every four spoken by people in societies that produce and process food. A closer examination of hunter-gatherer languages in Greenland, southern Africa and Australia found few instances of labiodental sounds. Historical records indicate that words with labiodental sounds were borrowed during contacts with people from industrialized nations, the researchers say.