Using a data analysis of thousands of languages and studying a unique subset of celebrities, anthropologist Caleb Everett and former student Sihan Chen revealed that a soft food diet, compared with the diet of hunter-gatherers, reconstruct dentition and changes how people speak.
The study addressed a long-held belief that languages are susceptible to the same pressures and are essentially immune to external factors.
The results of the study offer significant evidence that languages are affected by external factors that differ across populations.
Everett said, “Languages change—we can see this in any language—but the thinking has long been that all languages have the same pressures, that there is no difference across populations that make some people more prone than others to use certain sounds.”
“In the past decade, we have produced new evidence suggesting that there might be other factors that are likely to influence speech patterns. We have spent several years studying how environmental factors such as ambient aridity—extreme dryness—shift speech patterns by reducing vowel usage, which requires more effort to pronounce.”
“Sihan took a linguistics course and fell in love with the study of languages. An exceptionally bright student, he demonstrated an incredible aptitude for phonetics and transcribing precisely what’s going on in people’s mouths as they speak.”
“Yet language changes take hundreds of years to emerge. So, to obtain a quicker accounting, the two examined the speech patterns of 10 celebrities—including British singing phenom Freddie Mercury and former Olympic swimmer Michael Phelps—a research subset that offered a spectrum of dentition variance.”
Mercury’s four other teeth—a hereditary dental condition—caused a famously unusual overbite.
From a research perspective, Everett realized that using the ten celebrities’ data was “a bit tricky.”
He said, “Freddie Mercury’s bite isn’t the way that it is because of his diet; there are genetic factors here. Yet the data from the celebrities provide us insight in real-time and contributes to understanding this story of human language that is changing over time.”
In meticulously transcribing the celebrities’ online videos, Chen focused on establishing the ratio of labiodental sounds such as “f” and “v”—sounds common today but that rarely existed until soft diets became pervasive. In particular, Mercury was known to pronounce these particular sounds with abnormal frequency due to his dental abnormality.
Everett said, “He was extreme because he produced these labiodental sounds all over the place even when they shouldn’t be there. On the other end of the spectrum, Michael Phelps is doing the reverse.”
While studying several languages, scientists established two linguistic camps—hunter-gatherers, whose diets have changed little and whose mouths get a lot more wear, and non-hunter-gatherers.
Previous research on the subject has examined whether languages have this sound, or they don’t. Everett and Chen delved deeper, analyzing the ratios of frequency between the two research groups.
Everett said, “We adopted a whole new series of methods to test this, and we found extensive support for it, yet the findings show correlational, not causal, links between diet, dentition, and speech patterns.”
“These pressures are subtle and operate over hundreds and thousands of years, so it’s a hard thing to know for sure. But what we see are these probabilistic tendencies in the world’s 7,000 languages.”
“These new findings provide a better understanding of why languages—which are a key distinguishing characteristic for anthropologists and a key aspect of being human—take the shape they do, how they diverge, and what factors impact their evolvement.”
- Caleb Everett et al., Speech adapts to dentition differences within and across populations, Scientific Reports (2021). DOI: 10.1038/s41598-020-80190-8