The languages of the world and their sounds are as diverse as the people who speak them. Frequent consonants like “m” and vowels like “a” occur as well as the rare clicking sounds of some languages in southern Africa. But how did these sounds and languages develop and where do sounds like “f” and “w” come from? A team of researchers from the University of Zurich, two MaxPlanckInstitutes, the University of Lyon and the Nanyang Technological University in Singapore have now discovered that some sounds developed much later than previously assumed. Until now, it was assumed that the sound spectrum stabilized with the emergence of Homo sapiens about 300,000 years ago. The results of the latest study show, however, that sounds such as “f” and “v”, which occur in numerous languages, only spread relatively recently. This was due to a new tooth position, which in turn developed as a result of changing eating habits.

“Paleoanthropological evidence suggests that the production apparatus has undergone a fundamental change of this kind since the Neolithic,” the scientists write in their article published in the journal Science. “Although humans usually begin with vertical and horizontal overlapping in their bite arrangement (overbite), the chewing effort in the Palaeolithic after adolescence led to an edge-to-edge bite.

SOFT FOOD VS. HARD FOOD

Early humans from the time of the hunters and gatherer, who had exclusively hard food at their disposal, thus developed a so-called head-bite as adults, with which the incisors of the upper and lower jaw meet vertically. Nowadays humans have a denture-form though, with which the upper incisors protrude slightly over the lower ones. This developed over the course of the time through the increase of soft food.

Through this new denture-form also new sounds, that occur in approximately half of all languages in the world today, developed. With the so-called labiodentals – e.g. with the pronunciation of “f” – the upper incisors touch the lower lip. With a head bite, however, sounds such as “f” and “v” are very difficult to form.

“In Europe, we have seen a drastic increase in labiodentals over the last two millennia which can be attributed to the increasing distribution of processed, softer food and the introduction of industrial grinding processes,” explains Steven Moran, one of the two leading co-authors. “The impact of our biological conditions on sound development has thus far been underestimated.”

Biomechanical models of the speech apparatus would show that labiodental sounds in the overbite configuration has about 30% less muscle effort than in the edge-to-edge bite configuration, the researchers emphasize. In bilabial sounds such as “m,” “p” or the English pronunciation of “w”, where the upper lip touches the lower lip instead of the teeth, this difference does not exist.

TESTING A HYPOTHESIS

The researchers were inspired by the linguist Charles Hockett, who more than 30 years ago already found that the language of population groups with access to softer food is frequently dominated by labiodentals. “But there are dozens of flimsy correlations in the field of