Wednesday, December 6

You Sound How You Eat: Speech Evolved As Diet Changed

A surprising new study has revealed that diverse sounds produced by human speech not only evolved after Neolithic times but also stem from biological alterations in the human bite as a result of eating softer diets.

The findings contradict the theory that the range of human sounds has not changed since Homo sapiens emerged about 300,000 years ago. Linguistic diversity was also commonly thought to evolve independently of biological changes.

In 1985, linguist Charles Hockett suggested that labiodentals – the class of speech sounds including ‘f’ and ‘v’ in English – might have evolved as diets became softer with the move away from hunting and gathering towards agriculture and industrialized food processing.

These changes, he said, altered the human bite so that new sounds were easier to produce.

Damian Blasi and Steven Moran, researchers from the Department of Comparative Linguistics at the University of Zurich in Switzerland, thought the proposal was intriguing.

Their investigations revealed that labiodental sounds arose recently and that they did indeed stem from changes in diet and bite just as Hockett hypothesized.

“Soft diets led to the preservation of overbite and overjet, which characterizes the majority of the bites that people have nowadays,” Blasi explains. These rendered labiodental sounds low cost, or “easy” to produce.

“Since our upper teeth protrude from our mouth, they can touch the lower lips with very little effort,” he says.

“Before, heavy wear diets produced an edge-to-edge bite so the upper teeth didn’t protrude, and hence it was harder to produce those sounds. Try it yourself – put your upper and lower teeth in contact then try to produce an ‘f’.”

The team’s research suggests that the sounds originated not long before the Bronze Age in Europe and Asia. They suspect they emerged from bilabials, another class of speech sounds which include, for instance, ‘b’.

The authors explore how labiodentals might be “useful” sounds for communicating.

Read more at Cosmos Magazine