Tuesday, October 19, 2021

How Farming Reshaped Our Smiles and Our Speech

 From Science:

Postdocs Damián Blasi and Steven Moran in Bickel's lab set out to test an idea proposed by the late American linguist Charles Hockett. He noted in 1985 that the languages of hunter-gatherers lacked labiodentals, and conjectured that their diet was partly responsible: Chewing gritty, fibrous foods puts force on the growing jaw bone and wears down molars. In response, the lower jaw grows larger, and the molars erupt farther and drift forward on the protruding lower jaw, so that the upper and lower teeth align. That edge-to-edge bite makes it harder to push the upper jaw forward to touch the lower lip, which is required to pronounce labiodentals. But other linguists rejected the idea, and Blasi says he, Moran, and their colleagues "expected to prove Hockett wrong."

First, the six researchers used computer modeling to show that with an overbite, producing labiodentals takes 29% less effort than with an edge-to-edge bite. Then, they scrutinized the world's languages and found that hunter-gatherer languages have only about one-fourth as many labiodentals as languages from farming societies. Finally, they looked at the relationships among languages, and found that labiodentals can spread quickly, so that the sounds could go from being rare to common in the 8000 years since the widespread adoption of agriculture and new food processing methods such as grinding grain into flour. (Read more.)


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