If it weren’t for farmers and soft food, we wouldn’t be able to utter the f-word, or any word that has the sound “f” or “v” for that matter. A new study revealed that the switch to processed food after the spread of agriculture gave humans an overbite and eventually two labiodental sounds that exist in more than half of the world languages.

The idea was proposed 30 years ago by the renowned linguist Charles Hockett who pointed out that labiodental sounds such as “f” and “v” were more common among languages spoken by people in societies that ate softer foods and completely lacking in languages spoken by hunter-gatherers. To explain this tendency, a team of researchers led by Damián Blasi at the University of Zurich, Switzerland, set out on an expedition to unravel this mystery.

The study, published in Science in March 2019, revealed something fascinating. Ancient humans had a slightly different jaw structure. The lower and upper incisors were aligned, making it difficult to articulate labiodental sounds which are essentially produced by pushing the upper teeth against the lower lip. We had aligned incisors because our diet depended entirely on chewing gritty, fibrous foods that put force on the jaw bone. Eventually, the lower jaw grew larger, and the molars erupt farther and drift forward on the protruding lower jaw so that the upper and lower teeth align.

Later, our jaws changed to an overbite structure making it practically easy to articulate labiodentals. The team showed that this change in bite correlated with the advent of agriculture in the Neolithic period 12000 years ago. The development of agriculture brought a change in diet; food became much easier to chew and as a result, the jaw bone doesn’t have to do much work and it eventually grew smaller resulting in an overbite.

To confirm this, the researchers scrutinized the languages of the world and found an interesting pattern. There was a global change in the sounds of most languages after the Neolithic era, with the use of “f” and “v” increasing dramatically in recent millennia. These sounds spread so quickly and they went from being rare to common in the 8000 years since the widespread adoption of agriculture and food processing methods. That’s partly the reason why Proto-Indo-European patēr changed to Old English faeder about 1500 years ago.

The study challenges and overturns the prevailing assumption that all human speech sounds were present around 300.000 ago when Homo sapiens evolved. “The set of speech sounds we use has not necessarily remained stable since the emergence of our species, but rather the immense diversity of speech sounds that we find today is the product of a complex interplay of factors involving biological change and cultural evolution,” said Steven Moran , a team member and linguist at the University of Zurich.

This new approach to studying language evolution is a groundbreaking, says Sean Roberts at the University of Bristol, UK. “For the first time, we can look at patterns in global data and spot new relationships between the way we speak and the way we live,” he says. “It’s an exciting time to be a linguist.”

Journal reference: Science, DOI: 10.1126/science.aav3218