How Diet May Have Changed the Way Humans Speak

'Ancient hunter-gathererers often had front teeth that met together, unlike today's more common alignment where the upper front teeth 'overbite' the lower front teeth,' writes Slashdot reader omfglearntoplay. 'This malocclusion is a result of changes to the ancestral human diet and introduction of soft foods, according to a new study published in the journal Science.' ABC News reports: More than 2,000 different sounds exist across the roughly 7,000 to 8,000 languages that humans speak today, from ubiquitous cardinal vowels such as 'a' and 'i' to the rare click consonants found in southern Africa. Scientists had long thought this range of sounds was fixed in human biology since at least the emergence of our species about 300,000 years ago. However, in 1985, linguist Charles Hockett noted that labiodentals -- sounds produced by positioning the lower lip against the upper teeth, including 'f' and 'v' -- are overwhelmingly absent in languages whose speakers are hunter-gatherers. He suggested tough foods associated with such diets favored bites where teeth met edge on edge, and that people with such teeth would find it difficult to pronounce labiodentals, which are nowadays found in nearly half the world's languages.

To explore Hockett's idea further, researchers developed computer models of the human skull, teeth and jaw in overbite, overjet and edge-on-edge bite configurations. They next analyzed the amount of effort these configurations needed to pronounce certain labiodental sounds. The scientists found that overbites and overjets required 29 percent less muscular effort to produce labiodental sounds than edge-on-edge bites. In addition, overbites and overjets made it easier to accidentally mispronounce bilabial sounds such as 'm,' 'w' or 'p,' which are made by placing the lips together, as labiodental ones. The researchers also discovered that hunter-gatherer societies only have about 27 percent the number of labiodentals found in agricultural societies. 'Moreover, when they focused on the Indo-European language family -- which stretches from Iceland to the eastern Indian state of Assam and has records stretching back more than 2,500 years on how sounds in some of its languages were pronounced -- they found the use of labiodentals increased steadily following the development of agriculture,' the report says. 'All in all, they estimated that labiodentals only had a 3 percent chance of existing in the Indo-European proto-language that emerged about 6,000 to 8,000 years ago but are now found in 76 percent of the family's languages.'

Read more of this story at Slashdot.