The Wall Street Journal has an interesting article about the evolution of speech.

Wall Street Journal

A shift to softer foods with the advent of agriculture contributed to changes in the human bite and jaw in the post-Neolithic age, say researchers. That enhanced humans’ ability to produce ‘f’ and ‘v’ sounds.

By Brianna Abbott
Updated March 14, 2019 4:40 p.m. ET

A change in ancient diet may have altered the way humans speak, and potentially spawned an increased use of words that include “f” and “v” sounds, says a new study that may offer insights into the development of language.

A shift to softer foods with the advent of agriculture contributed to changes in the human bite and jaw in the post-Neolithic age, say the researchers, who described their findings in the journal Science. That in turn enhanced humans’ ability to produce “f” and “v” sounds, now found in about half of languages, they say.

Modern humans communicate in roughly 7,000 different languages, a compilation of diverse sounds and gestures. Their origins involve a mixture of cultural, historical and social factors that come together to create the way we speak and connect.

Biology and physiology, however, have largely stayed out of the linguistic picture, partially because it is challenging to collect both biological and linguistic evidence from the ancient past.

In the new study, the research team from the University of Zurich tested an idea put forth in 1985 by linguist Charles Hockett. He surmised that the advent of agriculture most likely increased the use of sounds known as “labiodentals”—sounds like “f” and “v” made by touching our bottom lip to our top teeth—in some languages because the resulting changes in jaw and bite would make them easier to say.

The idea was dismissed at the time. But recent evidence shows that the development of agriculture and the resulting softer foods also corresponded to a change in jaw and bite structure (and many modern dental problems).

In childhood, humans typically have both overbite, where top teeth overlap the bottom, and overjet, with top teeth more forward than the lower, the researchers note. But the tough food sources of hunter gatherers required more chewing and grinding of their teeth, resulting in the alignment of their top and bottom teeth in an “edge-to-edge” bite by the time they reach adulthood. Without that extra work, humans eventually evolved smaller jaws and more often kept the overbite.

To see if this change in structure resulted in a change of effort, the researchers created simulations of jaws with edge-to-edge and overbite and calculated the effort it took to produce certain sounds. They found that “f” and “v” sounds were 29% less costly to say with an overbite. So-called bilabial sounds, like “p” and “w,” however, became slightly more costly with the change, though they were still easier to say overall.

Because labiodentals became easier to say, it became more likely that humans would make those sounds accidentally and that they would slip into the vernacular, the researchers say.

“Language is not just a random collection of sounds, but it’s biased by the sounds that are easy for us to make,” says Mark Pagel, an evolutionary biologist at the University of Reading not involved in the work. “We make sounds accidentally, and they get picked up by the language.”

The researchers then checked their idea in a global database of languages and determined that the languages that originated from hunter-gatherer societies used 27% fewer labiodentals in their words than food-producing societies.

They also examined native languages in Greenland, southern Africa and Australia, where edge-to-edge bite is well-documented. Most of the languages lacked labiodental sounds, and the languages that did have the sounds were often spoken by societies that had contact with different, labiodental-producing groups, the study found.

“We were amazed at how well it worked out in terms of the convergence of the evidence,” says Balthasar Bickel, a professor of general linguistics at the University of Zurich and senior researcher on the study. “That really surprised us.”

The study has been met with a combination of skepticism, interest and excitement. “I think for each individual piece of evidence, one could find arguments against it. However, all the evidence points in the same direction,” says Bart de Boer, a professor at the Vrije Universiteit in Brussels who studies the evolution of speech. “I think it’s quite an achievement.”

Many experts, including the authors, hope that the finding sparks new research that looks at language not only through the lenses of culture and time, but also through biology. “We weren’t always as we are now,” says Shara Bailey, an anthropologist who specializes in dental morphology at New York University. “Humans do adapt, and language might be one of those things that are influenced by our morphology.”