A class of speech sounds that is now present in nearly half of the world’s languages — labiodentals, produced by positioning the lower lip against the upper teeth, such as in ‘f’ or ‘v’ — are a relatively recent development, one brought about by post-Neolithic diet-induced changes in the human bite. That’s according to a paper published in the March 15, 2019 issue of the journal Science.
Paleolithic edge-to-edge bite (top) and a modern overbite/overjet bite (bottom) and how ‘f’ sounds are produced in a biomechanical model. Image credit: Timea Bodogan / Scott Moisik.
Human speech is incredibly diverse, ranging from ubiquitous sounds like ‘m’ and ‘a’ to the rare click consonants in some languages of Southern Africa.
However, this range of sounds is generally thought to have been established with the emergence of Homo sapiens around 300,000 years ago — independent of any changes in human biology after that time.
Dr. Damian Blasi from the University of Zurich and co-authors undertook a detailed interdisciplinary investigation of how speech sounds were shaped by changes in human bite as diet changed, particularly as humans transitioned away from hunting and gathering.
“Our study was inspired by an observation made by linguist Charles Hockett back in 1985,” they explained.
“Hockett noticed that languages that foster labiodentals are often found in societies with access to softer foods.”
The team found that a shift in adult tooth structure that kept adult’s upper teeth slightly more in front as compared to the lower teeth — a shift that correlated with the rise of food processing technology such as industrial milling — led to the rise of labiodentals.
“In Europe, our data suggests that the use of labiodentals has increased dramatically only in the last couple of millennia, correlated with the rise of food processing technology such as industrial milling,” said study co-author Dr. Steven Moran, also from the University of Zurich.
“The influence of biological conditions on the development of sounds has so far been underestimated.”
“Our results shed light on complex causal links between cultural practices, human biology and language,” said University of Zurich’s Professor Balthasar Bickel, senior author of the study.
“They also challenge the common assumption that, when it comes to language, the past sounds just like the present.”
“Based on the findings of the study and the new methods it developed, linguists can now tackle a host of unsolved questions, such as how languages actually sounded thousands of years ago.”
_____
D.E. Blasi et al. 2019. Human sound systems are shaped by post-Neolithic changes in bite configuration. Science 363 (6432); doi: 10.1126/science.aav3218
